Author: "Barnard, Monica" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Barnard, Monica"' showing total 88 results

Start Over Author "Barnard, Monica"

88 results on '"Barnard, Monica"'

1. Very high-energy gamma rays from GRB 180720B and GRB 190829A with external Compton emission

Author: Barnard, Monica, Razzaque, Soebur, and Joshi, Jagdish C.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Gamma-ray bursts (GRBs) comprise of short, bright, energetic flashes of emission from extragalactic sources followed by a longer afterglow phase of decreased brightness. Recent discoveries of very-high-energy (VHE, $\gtrsim 100$ GeV) afterglow emission from GRB 180720B and GRB 190829A by H.E.S.S. have raised questions regarding the emission mechanism responsible. We interpret these observed late-time emission to be the result of inverse Compton emission of ultra-relativistic electrons in the GRB blastwave in an external radiation field, i.e., external Compton (EC), considering both the wind and interstellar medium scenarios. We present predictions of multiwavelength light curves and energy spectra, ranging from optical to VHE, and include the synchrotron and synchrotron self-Compton (SSC) radiation mechanisms as well. We corrected the EC and SSC model for the $\gamma$-ray attenuation by absorption of photons through their interaction with the extragalactic background light (EBL). We compared our results to multiwavelength data and found that EC gives a satisfactory fit for a given set of fixed model parameters for GRB 180720B, whereas SSC result in a better fit for GRB 190829A. For both GRBs a wind environment is preferred over constant density inter-stellar medium, and the Cosmic Microwave Background as the external radiation field. However, with more data and an effective optimisation tool we can find a more robust fit of the model, implying better constraints on the GRB environment and the particle energy requirements for the emission observed at late times. This has consequences for future observations of GRBs at these extreme energies., Comment: 7 pages, 5 figures, accepted for publication in MNRAS
Published: 2023
Full Text: View/download PDF

2. Probing the High-energy $\gamma$-ray Emission Mechanism in the Vela Pulsar via Phase-resolved Spectral and Energy-dependent Light Curve Modeling

Author: Barnard, Monica, Venter, Christo, Harding, Alice K., Kalapotharakos, Constantinos, and Johnson, Tyrel J.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Recent kinetic simulations sparked a debate regarding the emission mechanism responsible for pulsed GeV $\gamma$-ray emission from pulsars. Some models invoke curvature radiation, while other models assume synchrotron radiation in the current-sheet. We interpret the curved spectrum of the Vela pulsar as seen by H.E.S.S. II (up to $\sim$100 GeV) and the $Fermi$ Large Area Telescope (LAT) to be the result of curvature radiation due to primary particles in the pulsar magnetosphere and current sheet. We present phase-resolved spectra and energy-dependent light curves using an extended slot gap and current sheet model, invoking a step function for the accelerating electric field as motivated by kinetic simulations. We include a refined calculation of the curvature radius of particle trajectories in the lab frame, impacting the particle transport, predicted light curves, and spectra. Our model reproduces the decrease of the flux of the first peak relative to the second one, evolution of the bridge emission, near-constant phase positions of peaks, and narrowing of pulses with increasing energy. We can explain the first of these trends because we find that the curvature radii of the particle trajectories in regions where the second $\gamma$-ray light curve peak originates are systematically larger than those associated with the first peak, implying that the spectral cutoff of the second peak is correspondingly larger. However, an unknown azimuthal dependence of the $E$-field as well as uncertainty in the precise spatial origin of the GeV emission, precludes a simplistic discrimination of emission mechanisms., Comment: 24 pages, 19 figures, accepted by ApJ
Published: 2021
Full Text: View/download PDF

3. Modelling energy-dependent pulsar light curves due to curvature radiation

Author: Barnard, Monica, Venter, Christo, Harding, Alice K., and Kalapotharakos, Constantinos
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Pulsars emit pulsed emission across the entire electromagnetic spectrum and their light curve phenomenology is strongly dependent on energy. This is also true for the gamma-ray waveband. Continued detections by Fermi Large Area Telescope in the GeV band and ground-based Cherenkov telescopes in the TeV band (e.g., Crab and Vela above 1 TeV) raise important questions about our understanding of the electrodynamics and local environment of pulsar magnetospheres. We model energy-dependent light curves (as a function of geometry, e.g., pulsar inclination and observer angle) in the curvature radiation domain using a full emission code. We will discuss our refined calculation of the curvature radius of the particle trajectory and the effect thereof on the expected light curve shapes, as well as the origin of the light curve peaks in the magnetosphere. Our modelling should aid in differentiating between different emission mechanisms, as well as constraining the emission geometry by comparing our predictions to multi-wavelength data., Comment: 8 pages, 6 figures, Proceedings of the 5th Annual Conference on High Energy Astrophysics in Southern Africa (HEASA2017), accepted for publication in the online journal Proceedings of Science (ISSN 1824-8039) at https://pos.sissa.it. arXiv admin note: text overlap with arXiv:1710.08677
Published: 2018

4. Multi-TeV Emission From the Vela Pulsar

Author: Harding, Alice K., Kalapotharakos, Constantinos, Barnard, Monica, and Venter, Christo
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Pulsed emission from the Vela pulsar at energies above 3 TeV has recently been detected by the H.E.S.S. II air-Cherenkov telescope. We present a model for the broad-band spectrum of Vela from infra-red (IR) to beyond 10 TeV. Recent simulations of the global pulsar magnetosphere have shown that most of the particle acceleration occurs in the equatorial current sheet outside the light cylinder and that the magnetic field structure is nearly force-free for younger pulsars. We adopt this picture to compute the radiation from both electron-positron pairs produced in polar cap cascades and from primary particles accelerated in the separatrix and current sheet. The synchrotron spectrum from pairs resonantly absorbing radio photons at relatively low altitude can account for the observed IR-optical emission. We set the parallel electric field in the current sheet to produce the Fermi GeV emission through curvature radiation, producing particles with energies of 30-60 TeV. These particles then produce Very-High-Energy emission up to around 30 TeV through inverse-Compton scattering of the IR-Optical emission. We present model spectra and light curves that can match the IR-Optical, GeV and make predictions for the multi-TeV emission., Comment: 11 pages, 3 figures, accepted for publication in Astrophysical Journal Letters
Published: 2018
Full Text: View/download PDF

5. Modelling energy-dependent pulsar light curves

Author: Venter, Christo, Barnard, Monica, Harding, Alice K., and Kalapotharakos, Constantinos
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: In recent years, surprise discoveries of pulsed emission from the Crab and Vela pulsars above 100 GeV have drawn renewed attention to this largely unexplored region of the energy range. In this paper, we discuss example light curves due to curvature emission, with good resolution in the different energy bands. Continued light curve modelling may help to discriminate between different emission mechanisms, as well as constrain the location where emission is produced within the pulsar magnetosphere, including regions beyond the light cylinder., Comment: 4 pages, 2 figures, Conference Proceedings IAU Symposium: Pulsar Astrophysics The Next 50 Years
Published: 2017
Full Text: View/download PDF

6. High-energy pulsar light curves in an offset polar cap $B$-field geometry

Author: Barnard, Monica, Venter, Christo, and Harding, Alice K.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The light curves and spectral properties of more than 200 $\gamma$-ray pulsars have been measured in unsurpassed detail in the eight years since the launch of the hugely successful Fermi Large Area Telescope (LAT) $\gamma$-ray mission. We performed geometric pulsar light curve modelling using static, retarded vacuum, and offset polar cap (PC) dipole $B$-fields (the latter is characterized by a parameter $\epsilon$), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. In addition to constant-emissivity geometric models, we also considered a slot gap (SG) $E$-field associated with the offset-PC dipole $B$-field and found that its inclusion leads to qualitatively different light curves. We therefore find that the assumed $B$-field and especially the $E$-field structure, as well as the emission geometry (magnetic inclination and observer angles), have a great impact on the pulsar's visibility and its high-energy pulse shape. We compared our model light curves to the superior-quality $\gamma$-ray light curve of the Vela pulsar (for energies $>100$ MeV). Our overall optimal light curve fit (with the lowest $\chi^2$ value) is for the retarded vacuum dipole field and OG model. We found that smaller values of $\epsilon$ are favoured for the offset-PC dipole field when assuming constant emissivity, and larger $\epsilon$ values are favoured for variable emissivity, but not significantly so. When we increased the relatively low SG $E$-fields we found improved light curve fits, with the inferred pulsar geometry being closer to best fits from independent studies in this case. In particular, we found that such a larger SG $E$-field (leading to variable emissivity) gives a second overall best fit. This and other indications point to the fact that the actual $E$-field may be larger than predicted by the SG model., Comment: 13 pages, 5 figures, paper to appear in the Proceedings of High-Energy Astrophysics in Southern Africa (HEASA) 2016, ed. M. Boettcher, D. Buckley, S. Colafrancesco, P. Meintjes, and S. Razzaque
Published: 2017

7. Modelling very high-energy gamma rays detected from GRB 190829A: A comparative study

Author: Barnard, Monica, primary, Razzaque, Soebur, additional, and Joshi, Jagdish, additional
Published: 2024
Full Text: View/download PDF

8. The effect of an offset polar cap dipolar magnetic field on the modeling of the Vela pulsar's $\gamma$-ray light curves

Author: Barnard, Monica, Venter, Christo, and Harding, Alice K.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole $B$-fields (the latter is characterized by a parameter $\epsilon$), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole $B$-field mimics deviations from the static dipole (which corresponds to $\epsilon=0$). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) $E$-field associated with the offset-PC dipole $B$-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low $E$-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle $\alpha=78{_{-1}^{+1}}^{\circ}$ and observer angle $\zeta=69{_{-1}^{+2}}^{\circ}$. For this $B$-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of $\epsilon$ are favored for the offset-PC dipole field when assuming constant emissivity, and larger $\epsilon$ values favored for variable emissivity, but not significantly so. When multiplying the SG $E$-field by a factor of 100, we found improved light curve fits, with $\alpha$ and $\zeta$ being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes., Comment: 42 pages, 17 figures
Published: 2017
Full Text: View/download PDF

9. Very high energy gamma-rays from GRB 180720B and GRB 190829A with external Compton emission

Author: Barnard, Monica, primary, Razzaque, Soebur, additional, and Joshi, Jagdish C, additional
Published: 2023
Full Text: View/download PDF

10. Very high energy gamma-rays from GRB 180720B and GRB 190829A with external Compton emission.

Author: Barnard, Monica, Razzaque, Soebur, and Joshi, Jagdish C
Subjects: GAMMA ray bursts, COMPTON scattering, COSMIC background radiation, INVERSE Compton scattering, RELATIVISTIC electrons, INTERSTELLAR medium
Abstract: Gamma-ray bursts (GRBs) comprise short, bright, energetic flashes of emission from extragalactic sources followed by a longer afterglow phase of decreased brightness. Recent discoveries of very high energy (VHE, ≳100 GeV) afterglow emission from GRB 180720B and GRB 190829A by the High Energy Stereoscopic System have raised questions regarding the emission mechanism responsible. We interpret this observed late-time emission to be the result of inverse Compton emission of ultrarelativistic electrons in the GRB blast wave in an external radiation field, i.e. external Compton (EC), considering both the wind and interstellar medium scenarios. We present predictions of multiwavelength light curves and energy spectra, ranging from optical to VHE, and include the synchrotron and synchrotron self-Compton (SSC) radiation mechanisms as well. We corrected the EC and SSC models for the gamma-ray attenuation by absorption of photons through their interaction with the extragalactic background light. We compared our results to multiwavelength data and found that EC gives a satisfactory fit for a given set of fixed model parameters for GRB 180720B, whereas SSC results in a better fit for GRB 190829A. For both GRBs, a wind environment is preferred over constant-density interstellar medium, and the cosmic microwave background as the external radiation field. However, with more data and an effective optimization tool we can find a more robust fit of the model, implying better constraints on the GRB environment and the particle energy requirements for the emission observed at late times. This has consequences for future observations of GRBs at these extreme energies. [ABSTRACT FROM AUTHOR]
Published: 2024
Full Text: View/download PDF

11. Meta analytic review of interventions using three types of indirect contact to reduce intergroup bias in children and adolescents

Author: Barnard, Monica
Published: 2022
Full Text: View/download PDF

12. Probing the High-energy Gamma-Ray Emission Mechanism in the Vela Pulsar via Phase-resolved Spectral and Energy-dependent Light-curve Modeling

Author: Barnard, Monica, primary, Venter, Christo, additional, Harding, Alice K., additional, Kalapotharakos, Constantinos, additional, and Johnson, Tyrel J., additional
Published: 2022
Full Text: View/download PDF

13. Revisiting the PeVatron candidate MGRO J1908+06 with an updated H.E.S.S. analysis

Author: Abdalla, Hassan, Aharonian, Felix, Barbosa Martins, Victor, Lohse, Thomas, Luashvili, Anna, Lypova, Iryna, Mackey, Jonathan, Majumdar, Jhilik, Malyshev, Denys, MALYSHEV, Dmitry, Marandon, Vincent, Marchegiani, Paolo, Marcowith, Alexandre, Barnacka, Anna, Mares, Arnaud, Marti'i-Devesa, Guillem, Marx, Ramin, Maurin, Gilles, Meintjes, Pieter, Meyer, Manuel, Moderski, Rafal, Mohrmann, Lars, de Ona Wilhelmi, E., Joshi, Vikas, Barnard, Monica, Mitchell, Alison, Montanari, Alessandro, Moore, Chris, Morris, Paul, Moulin, Emmanuel, Muller, Jacques, Murach, Thomas, Nakashima, Kaori, Naurois , Mathieu, Nayerhoda, Amid, Batzofin, Rowan, Ndiyavala, Hambeleleni, Niemiec, Jacek, Noel, Angel, O'Brien, Paul, Oberholzer, Laenita Lorraine, Ohm, Stefan, Khelifi, Bruno, Giunti, Luca, Olivera-Nieto, Laura, de Ona Wilhelmi, Emma Maria, Becherini, Yvonne, Ostrowski, Michal, Panny, Sebastian, Panter, Michael, Parsons, Dan, Peron, Giada, Pita, Santiago, Poireau, Vincent, Prokhorov, Dmitry, Prokoph, Heike, PUEHLHOFER, Gerd, Berge, David, Punch, Michael, Quirrenbach, Andreas, Reichherzer, Patrick, Reimer, Anita, Reimer, Olaf, Remy, Quentin, Renaud, Matthieu, Reville, Brian, Rieger, Frank, Romoli, Carlo, Bernloehr, Konrad, Rowell, Gavin, Rudak, Bronislaw, Rueda Ricarte, Hector, Ruiz Velasco, Edna, Sahakian, Vardan, Sailer, Simon, Salzmann, Heiko, Sanchez, David, Santangelo, Andrea, Sasaki, Manami, Bi, Baiyang, Schaefer, Johannes, Schutte, Hester, Schwanke, Ullrich, Schüssler, Fabian, Senniappan, Mohanraj, Seyffert, Albert, Shapopi, Jimmy N. S., Shiningayamwe, Kleopas, Simoni, Rachel, Sinha, Atreyee, Boettcher, Markus, Sol, Helene, Spackman, Hugh, Specovius, Andreas, Spencer, Samuel Timothy, Spir-Jacob, Marion, Stawarz, Lukasz, Steenkamp, Riaan, Stegmann, Christian, Steinmassl, Simon, Steppa, Constantin, Boisson, Catherine, Sun, Lei, Takahashi, Tadayuki, Tanaka, Takaaki, Tavernier, Thomas, Taylor, Andrew, Terrier, Regis, Thiersen, Hannes, Thorpe-Morgan, Charles, Tluczykont, Martin, Tomankova, Lenka, Ait-Benkhali, Faical, Bolmont, Julien, Tsirou, Michelle, Tsuji, Naomi, Tuffs, Richard, Uchiyama, Yasunobu, van der Walt, Johann, van Eldik, Christopher, van Rensburg, Carlo, van Soelen, Brian, Vasileiadis, George, Veh, Johannes, Bony , Mathieu, Venter, Christo, Vincent, Pascal, Vink, Jacco, Völk, Heinrich J., Wagner, Stefan, Watson, Jason John, Werner, Felix, White, Richard, Wierzcholska, Alicja, Wong, Yu Wun, Breuhaus, Mischa, Yassin, Hend, Yusafzai, Anke, Zacharias, Michael, Zanin, Roberta, Zargaryan, Davit, Zdziarski, Andrzej, Zech, Andreas, Zhu, Sylvia Jiechen, Zmija, Andreas, Zouari, Samuel, Brose, Robert, Zywucka, Natalia, H. E. S. S. Collaboration, Brun, Francois, Bulik, Tomasz, Bylund, Thomas, Cangemi, Floriane, Caroff, Sami, Casanova, Sabrina, Anguener, Oguzhan, Catalano, Jaqueline, Chambery, Pauline, Chand, Tej Bahadur, Chen, Andrew, Cotter, Garret, Curlo, Malgorzata, Dalgleish, Hannah, Mbarubucyeye, Jean Damascene, Davids, Isak Delberth, Davies, James, Arcaro, Cornelia, Devin, Justine, Djannati-Ataï, Arache, Dmytriiev, Anton, Donath, Axel, Doroshenko, Victor, Dreyer, Lente, Du Plessis, Louis, Duffy, Connor, Egberts, Kathrin, Einecke, Sabrina, Armand, Celine, ERNENWEIN, Jean-Pierre, Fegan, Steven, Feijen, Kirsty, Fiasson, Armand, Fichet de Clairfontaine, Gaëtan, Fontaine, Gerard, Frans, Lott, Füssling, Matthias, Funk, Stefan, Gabici, Stefano, Armstrong, Tom, Gallant, Yves, Giavitto, Gianluca, Glawion, Dorit, Glicenstein, Jean-Francois, Grondin, Marie-Hélène, Hattingh, Sumari, Haupt, Maria, HERMANN, German, Hinton, Jim, Hofmann, Werner, Ashkar, Halim, Hoischen, Clemens, Holch, Tim Lukas, Holler, Markus, Horns, Dieter, Huang, Zhiqiu, Huber, David, Hörbe, Mario, Jamrozy, Marek, Jankowsky, Felix, JUNG, Ira, Backes, Michael, Kasai, Eli, Katarzynski, Krzysztof, Katz, Ulì, Khangulyan, Dmitry, Klepser, Stefan, Kluzniak, Wlodek, Komin, Nukri, Konno, Ruslan, Kosack, Karl, Kostiunin, Dmitriy, Baghmanyan, Vardan, Kreter, Michael, Kukec Mezek, Gašper, Kundu, Anu, Lamanna, Giovanni, Le Stum, Sébastien, Lemiere, Anne, Lemoine-Goumard, Marianne, Lenain, Jean-Philippe, Leuschner, Fabian, Levy, Christelle, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), H.E.S.S., Naurois , Mathieu, Bony , Mathieu, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Photon, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, Astrophysics, emission [photon], Acceleration, Pulsar, photon: emission, emission [gamma ray], Angular resolution, ddc:530, galaxy [gamma ray], Supernova remnant, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), gamma ray: galaxy, energy: high, cosmic radiation: propagation, Molecular cloud, gamma ray: emission, 13. Climate action, cosmic radiation: galaxy, Milagro, HESS - Abteilung Hinton, high [energy], galaxy [cosmic radiation], propagation [cosmic radiation], Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: 37th International Cosmic Ray Conference, ICRC 2021, Berlin, Germany - Online, 12 Jul 2021 - 23 Jul 2021; Proceedings of Science / International School for Advanced Studies (ICRC2021), 779 (2021). doi:10.22323/1.395.0779, Detecting and studying galactic gamma-ray sources emitting very-high energy photons sheds light on the acceleration and propagation of cosmic rays presumably created in these sources. Currently, there are few sources emitting photons with energies exceeding 100 TeV. In this work we revisit the unidentified source MGRO J1908+06, initially detected by Milagro, using an updated H.E.S.S. dataset and analysis pipeline. The vicinity of the source contains a supernova remnant and pulsars as well as molecular clouds. This makes the identification of the primary source(s) of galactic cosmic rays as well as the nature of the gamma-ray emission challenging, especially in light of the recent HAWC and LHAASO detection of the high energy tail of its spectrum. Exploiting the better angular resolution as compared to particle detectors, we investigate the morphology of the source as well as its spectral properties., Published by SISSA, Trieste
Published: 2021
Full Text: View/download PDF

14. Modelling Phase-resolved Spectra and Energy-dependent Light Curves of the Vela Pulsar to Scrutinize its GeV Emission Mechanism

Author: Barnard, Monica, primary, Venter, Christo, additional, Harding, Alice Kust, additional, Kalapotharakos, Constantinos, additional, and Johnson, Tyrel J., additional
Published: 2021
Full Text: View/download PDF

15. Astronomy outreach in Namibia: H.E.S.S. and beyond

Author: Dalgleish, Hannah, primary, Prokoph, Heike, additional, Zhu, Sylvia, additional, Backes, Michael, additional, Cotter, Garret, additional, Catalano, Jacqueline, additional, Ruiz Velasco, Edna, additional, Kasai, Eli, additional, Abdalla, Hassan, additional, Aharonian, Felix, additional, Ait-Benkhali, Faical, additional, Anguener, Oguzhan, additional, Arcaro, Cornelia, additional, Armand, Celine, additional, Armstrong, Tom, additional, Ashkar, Halim, additional, Baghmanyan, Vardan, additional, Barbosa Martins, Victor, additional, Barnacka, Anna, additional, Barnard, Monica, additional, Batzofin, Rowan William, additional, Becherini, Yvonne, additional, Berge, David, additional, Bernloehr, Konrad, additional, Bi, Baiyang, additional, Böttcher, Markus, additional, Boisson, Catherine, additional, Bolmont, Julien, additional, Bony (de), Mathieu, additional, Breuhaus, Mischa, additional, Brose, Robert, additional, Brun, Francois, additional, Bulik, Tomasz, additional, Bylund, Thomas, additional, Cangemi, Floriane, additional, Caroff, Sami, additional, Casanova, Sabrina, additional, Catalano, Jaqueline, additional, Chambery, Pauline, additional, Chand, Tej Bahadur, additional, Chen, Andrew, additional, Curlo, Malgorzata, additional, Damascene Mbarubucyeye, Jean, additional, Davids, Isak Delberth, additional, Davies, James, additional, Devin, Justine, additional, Djannati-Ataï, Arache, additional, Dmytriiev, Anton, additional, Donath, Axel, additional, Doroshenko, Victor, additional, Dreyer, Lente, additional, Du Plessis, Louis, additional, Duffy, Connor, additional, Egberts, Kathrin, additional, Einecke, Sabrina, additional, ERNENWEIN, Jean-Pierre, additional, Fegan, Steven, additional, Feijen, Kirsty, additional, Fiasson, Armand, additional, Fichet de Clairfontaine, Gaëtan, additional, Fontaine, Gerard, additional, Frans, Lott, additional, Fuessling, Matthias, additional, Funk, Stefan, additional, Gabici, Stefano, additional, Gallant, Yves, additional, Giavitto, Gianluca, additional, Giunti, Luca, additional, Glawion, Dorit, additional, Glicenstein, Jean-Francois, additional, Grondin, Marie-Hélène, additional, Hattingh, Sumari, additional, Haupt, Maria, additional, HERMANN, German, additional, Hinton, Jim, additional, Hofmann, Werner, additional, Hoischen, Clemens, additional, Holch, Tim, additional, Holler, Markus, additional, Horns, Dieter, additional, Huang, Zhi-Qiu, additional, Huber, David, additional, Hörbe, Mario, additional, Jamrozy, Marek, additional, Jankowsky, Felix, additional, Joshi, Vikas, additional, JUNG, Ira, additional, Katarzynski, Krzysztof, additional, Katz, Ulì, additional, Khangulyan, Dmitry, additional, Khelifi, Bruno, additional, Klepser, Stefan, additional, Kluzniak, Wlodek, additional, Komin, Nukri, additional, Konno, Ruslan, additional, Kosack, Karl, additional, Kostunin, Dmitriy, additional, Kreter, Michael, additional, Kukec Mezek, Gašper, additional, Kundu, Anu, additional, Lamanna, Giovanni, additional, Le Stum, Sebastien, additional, Lemiere, Anne, additional, Lemoine-Goumard, Marianne, additional, Lenain, Jean-Philippe, additional, Leuschner, Fabian, additional, Levy, Christelle, additional, Lohse, Thomas, additional, Luashvili, Anna, additional, Lypova, Iryna, additional, Mackey, Jonathan, additional, Majumdar, Jhilik, additional, Malyshev, Denys, additional, Malyshev, Dmitry, additional, Marandon, Vincent, additional, Marchegiani, Paolo, additional, Marcowith, Alexandre, additional, Mares, Arnaud, additional, Martí-Devesa, Guillem, additional, Marx, Ramin, additional, Maurin, Gilles, additional, Meintjes, Pieter, additional, Meyer, Manuel, additional, Mitchell, Alison, additional, Moderski, Rafal, additional, Mohrmann, Lars, additional, Montanari, Alessandro, additional, Moore, Chris, additional, Morris, Paul, additional, Moulin, Emmanuel, additional, Muller, Jacques, additional, Murach, Thomas, additional, Nakashima, Kaori, additional, Naurois (de), Mathieu, additional, Nayerhoda, Amid, additional, Davids, Hambeleleni, additional, Niemiec, Jacek, additional, Noel, Angel, additional, O'Brien, Paul, additional, Oberholzer, Laenita Lorraine, additional, Ohm, Stefan, additional, Olivera-Nieto, Laura, additional, Ona-Wilhelmi (de), Emma, additional, Ostrowski, Michal, additional, Panny, Sebastian, additional, Panter, Michael, additional, Parsons, Dan, additional, Peron, Giada, additional, Pita, Santiago, additional, Poireau, Vincent, additional, Prokhorov, Dmitry A, additional, PUEHLHOFER, Gerd, additional, Punch, Michael, additional, Quirrenbach, Andreas, additional, Reichherzer, Patrick, additional, Reimer, Anita, additional, Reimer, Olaf, additional, Remy, Quentin, additional, Renaud, Matthieu, additional, Reville, Brian, additional, Rieger, Frank, additional, Romoli, Carlo, additional, Rowell, Gavin P, additional, Rudak, Bronislaw, additional, Rueda Ricarte, Hector, additional, Sahakian, Vardan, additional, Sailer, Simon, additional, Salzmann, Heiko, additional, Sanchez, David, additional, Santangelo, Andrea, additional, Sasaki, Manami, additional, Schaefer, Johannes, additional, Schutte, Hester, additional, Schwanke, Ullrich, additional, Schüssler, Fabian, additional, Senniappan, Mohanraj, additional, Seyffert, Albert, additional, Shapopi, Jimmy N.S., additional, Shiningayamwe, Kleopas, additional, Simoni, Rachel, additional, Sinha, Atreyee, additional, Sol, Helene, additional, Spackman, Hugh, additional, Specovius, Andreas, additional, Spencer, Samuel Timothy, additional, Spir-Jacob, Marion, additional, Stawarz, Lukasz, additional, Steenkamp, Riaan, additional, Stegmann, Christian, additional, Steinmassl, Simon, additional, Steppa, Constantin, additional, Sun, Lei, additional, Takahashi, Tadayuki, additional, Tanaka, Takaaki, additional, Tavernier, Thomas, additional, Taylor, Andrew, additional, Terrier, Regis, additional, Thiersen, Hannes, additional, Thorpe-Morgan, Charles, additional, Tluczykont, Martin, additional, Tomankova, Lenka, additional, Tsirou, Michelle, additional, Tsuji, Naomi, additional, Tuffs, Richard, additional, Uchiyama, Yasunobu, additional, van der Walt, Johann, additional, van Eldik, Christopher, additional, van Rensburg, Carlo, additional, van Soelen, Brian, additional, Vasileiadis, George, additional, Veh, Johannes, additional, Venter, Christo, additional, Vincent, Pascal, additional, Vink, Jacco, additional, Völk, Heinrich J., additional, Wagner, Stefan, additional, Watson, Jason John, additional, Werner, Felix, additional, White, Richard, additional, Wierzcholska, Alicja, additional, Wong, Yu Wun, additional, Yassin, Hend Mahmoud, additional, Yusafzai, Anke, additional, Zacharias, Michael, additional, Zanin, Roberta, additional, Zargaryan, Davit, additional, Zdziarski, Andrzej, additional, Zech, Andreas, additional, Zmija, Andreas, additional, Zouari, Samuel, additional, and Żywucka, Natalia, additional
Published: 2021
Full Text: View/download PDF

16. The young massive stellar cluster Westerlund 1 in gamma rays as seen with H.E.S.S.

Author: Mohrmann, Lars, primary, Abdalla, Hassan, additional, Aharonian, Felix, additional, Ait-Benkhali, Faical, additional, Anguener, Oguzhan, additional, Arcaro, Cornelia, additional, Armand, Celine, additional, Armstrong, Tom, additional, Ashkar, Halim, additional, Backes, Michael, additional, Baghmanyan, Vardan, additional, Barbosa Martins, Victor, additional, Barnacka, Anna, additional, Barnard, Monica, additional, Batzofin, Rowan William, additional, Becherini, Yvonne, additional, Berge, David, additional, Bernloehr, Konrad, additional, Bi, Baiyang, additional, Böttcher, Markus, additional, Boisson, Catherine, additional, Bolmont, Julien, additional, Bony (de), Mathieu, additional, Breuhaus, Mischa, additional, Brose, Robert, additional, Brun, Francois, additional, Bulik, Tomasz, additional, Bylund, Thomas, additional, Cangemi, Floriane, additional, Caroff, Sami, additional, Casanova, Sabrina, additional, Catalano, Jaqueline, additional, Chambery, Pauline, additional, Chand, Tej Bahadur, additional, Chen, Andrew, additional, Cotter, Garret, additional, Curlo, Malgorzata, additional, Dalgleish, Hannah, additional, Damascene Mbarubucyeye, Jean, additional, Davids, Isak Delberth, additional, Davies, James, additional, Devin, Justine, additional, Djannati-Ataï, Arache, additional, Dmytriiev, Anton, additional, Donath, Axel, additional, Doroshenko, Victor, additional, Dreyer, Lente, additional, Du Plessis, Louis, additional, Duffy, Connor, additional, Egberts, Kathrin, additional, Einecke, Sabrina, additional, ERNENWEIN, Jean-Pierre, additional, Fegan, Steven, additional, Feijen, Kirsty, additional, Fiasson, Armand, additional, Fichet de Clairfontaine, Gaëtan, additional, Fontaine, Gerard, additional, Frans, Lott, additional, Fuessling, Matthias, additional, Funk, Stefan, additional, Gabici, Stefano, additional, Gallant, Yves, additional, Giavitto, Gianluca, additional, Giunti, Luca, additional, Glawion, Dorit, additional, Glicenstein, Jean-Francois, additional, Grondin, Marie-Hélène, additional, Hattingh, Sumari, additional, Haupt, Maria, additional, HERMANN, German, additional, Hinton, Jim, additional, Hofmann, Werner, additional, Hoischen, Clemens, additional, Holch, Tim, additional, Holler, Markus, additional, Horns, Dieter, additional, Huang, Zhi-Qiu, additional, Huber, David, additional, Hörbe, Mario, additional, Jamrozy, Marek, additional, Jankowsky, Felix, additional, Joshi, Vikas, additional, JUNG, Ira, additional, Kasai, Eli, additional, Katarzynski, Krzysztof, additional, Katz, Ulì, additional, Khangulyan, Dmitry, additional, Khelifi, Bruno, additional, Klepser, Stefan, additional, Kluzniak, Wlodek, additional, Komin, Nukri, additional, Konno, Ruslan, additional, Kosack, Karl, additional, Kostunin, Dmitriy, additional, Kreter, Michael, additional, Kukec Mezek, Gašper, additional, Kundu, Anu, additional, Lamanna, Giovanni, additional, Le Stum, Sebastien, additional, Lemiere, Anne, additional, Lemoine-Goumard, Marianne, additional, Lenain, Jean-Philippe, additional, Leuschner, Fabian, additional, Levy, Christelle, additional, Lohse, Thomas, additional, Luashvili, Anna, additional, Lypova, Iryna, additional, Mackey, Jonathan, additional, Majumdar, Jhilik, additional, Malyshev, Denys, additional, Malyshev, Dmitry, additional, Marandon, Vincent, additional, Marchegiani, Paolo, additional, Marcowith, Alexandre, additional, Mares, Arnaud, additional, Martí-Devesa, Guillem, additional, Marx, Ramin, additional, Maurin, Gilles, additional, Meintjes, Pieter, additional, Meyer, Manuel, additional, Mitchell, Alison, additional, Moderski, Rafal, additional, Montanari, Alessandro, additional, Moore, Chris, additional, Morris, Paul, additional, Moulin, Emmanuel, additional, Muller, Jacques, additional, Murach, Thomas, additional, Nakashima, Kaori, additional, Naurois (de), Mathieu, additional, Nayerhoda, Amid, additional, Davids, Hambeleleni, additional, Niemiec, Jacek, additional, Noel, Angel, additional, O'Brien, Paul, additional, Oberholzer, Laenita Lorraine, additional, Ohm, Stefan, additional, Olivera-Nieto, Laura, additional, Ona-Wilhelmi (de), Emma, additional, Ostrowski, Michal, additional, Panny, Sebastian, additional, Panter, Michael, additional, Parsons, Dan, additional, Peron, Giada, additional, Pita, Santiago, additional, Poireau, Vincent, additional, Prokhorov, Dmitry A, additional, Prokoph, Heike, additional, PUEHLHOFER, Gerd, additional, Punch, Michael, additional, Quirrenbach, Andreas, additional, Rauth, Romed, additional, Reichherzer, Patrick, additional, Reimer, Anita, additional, Reimer, Olaf, additional, Remy, Quentin, additional, Renaud, Matthieu, additional, Reville, Brian, additional, Rieger, Frank, additional, Romoli, Carlo, additional, Rowell, Gavin P, additional, Rudak, Bronislaw, additional, Rueda Ricarte, Hector, additional, Ruiz Velasco, Edna, additional, Sahakian, Vardan, additional, Sailer, Simon, additional, Salzmann, Heiko, additional, Sanchez, David, additional, Santangelo, Andrea, additional, Sasaki, Manami, additional, Schaefer, Johannes, additional, Schutte, Hester, additional, Schwanke, Ullrich, additional, Schüssler, Fabian, additional, Senniappan, Mohanraj, additional, Seyffert, Albert, additional, Shapopi, Jimmy N.S., additional, Shiningayamwe, Kleopas, additional, Simoni, Rachel, additional, Sinha, Atreyee, additional, Sol, Helene, additional, Spackman, Hugh, additional, Specovius, Andreas, additional, Spencer, Samuel Timothy, additional, Spir-Jacob, Marion, additional, Stawarz, Lukasz, additional, Steenkamp, Riaan, additional, Stegmann, Christian, additional, Steinmassl, Simon, additional, Steppa, Constantin, additional, Sun, Lei, additional, Takahashi, Tadayuki, additional, Tanaka, Takaaki, additional, Tavernier, Thomas, additional, Taylor, Andrew, additional, Terrier, Regis, additional, Thiersen, Hannes, additional, Thorpe-Morgan, Charles, additional, Tluczykont, Martin, additional, Tomankova, Lenka, additional, Tsirou, Michelle, additional, Tsuji, Naomi, additional, Tuffs, Richard, additional, Uchiyama, Yasunobu, additional, van der Walt, Johann, additional, van Eldik, Christopher, additional, van Rensburg, Carlo, additional, van Soelen, Brian, additional, Vasileiadis, George, additional, Veh, Johannes, additional, Venter, Christo, additional, Vincent, Pascal, additional, Vink, Jacco, additional, Völk, Heinrich J., additional, Wagner, Stefan, additional, Watson, Jason John, additional, Werner, Felix, additional, White, Richard, additional, Wierzcholska, Alicja, additional, Wong, Yu Wun, additional, Yassin, Hend Mahmoud, additional, Yusafzai, Anke, additional, Zacharias, Michael, additional, Zanin, Roberta, additional, Zargaryan, Davit, additional, Zdziarski, Andrzej, additional, Zech, Andreas, additional, Zhu, Sylvia, additional, Zmija, Andreas, additional, Zouari, Samuel, additional, and Żywucka, Natalia, additional
Published: 2021
Full Text: View/download PDF

17. Observation of burst activity from SGR1935+2154 associated to first galactic FRB with H.E.S.S

Author: Abdalla, Hassan, Aharonian, Felix, Barbosa Martins, Victor, Lenain, Jean-Philippe, Leuschner, Fabian, Levy, Christelle, Lohse, Thomas, Luashvili, Anna, Lypova, Iryna, Mackey, Jonathan, Majumdar, Jhilik, Malyshev, Denys, Malyshev, Dmitry, Barnacka, Anna, Marandon, Vincent, Marchegiani, Paolo, Marcowith, Alexandre, Mares, Arnaud, Martí-Devesa, Guillem, Marx, Ramin, Maurin, Gilles, Meintjes, Pieter, Meyer, Manuel, Mitchell, Alison, Barnard, Monica, Moderski, Rafal, Mohrmann, Lars, Montanari, Alessandro, Moore, Chris, Morris, Paul, Moulin, Emmanuel, Muller, Jacques, Murach, Thomas, Nakashima, Kaori, Naurois , Mathieu, Batzofin, Rowan, Nayerhoda, Amid, Davids, Hambeleleni, Niemiec, Jacek, Noel, Angel, O'Brien, Paul, Oberholzer, Laenita Lorraine, Ohm, Stefan, Olivera-Nieto, Laura, Ona-Wilhelmi , Emma, Ostrowski, Michal, Becherini, Yvonne, Panny, Sebastian, Panter, Michael, Parsons, Dan, Peron, Giada, Pita, Santiago, Poireau, Vincent, Prokhorov, Dmitry, Prokoph, Heike, PUEHLHOFER, Gerd, Punch, Michael, Berge, David, Quirrenbach, Andreas, Reichherzer, Patrick, Reimer, Anita, Reimer, Olaf, Remy, Quentin, Renaud, Matthieu, Reville, Brian, Rieger, Frank, Romoli, Carlo, Rowell, Gavin, Bernloehr, Konrad, Rudak, Bronislaw, Rueda Ricarte, Hector, Ruiz Velasco, Edna, Sahakian, Vardan, Sailer, Simon, Salzmann, Heiko, Sanchez, David, Santangelo, Andrea, Sasaki, Manami, Schaefer, Johannes, Bi, Baiyang, Schutte, Hester, Schwanke, Ullrich, Schüssler, Fabian, Senniappan, Mohanraj, Seyffert, Albert, Shapopi, Jimmy N. S., Shiningayamwe, Kleopas, Simoni, Rachel, Sinha, Atreyee, Sol, Helene, Böttcher, Markus, Spackman, Hugh, Specovius, Andreas, Spencer, Samuel Timothy, Spir-Jacob, Marion, Stawarz, Lukasz, Steenkamp, Riaan, Stegmann, Christian, Steinmassl, Simon, Steppa, Constantin, Sun, Lei, Boisson, Catherine, Takahashi, Tadayuki, Tanaka, Takaaki, Tavernier, Thomas, Taylor, Andrew, Terrier, Regis, Thiersen, Hannes, Thorpe-Morgan, Charles, Tluczykont, Martin, Tomankova, Lenka, Tsirou, Michelle, Ait-Benkhali, Faical, Bolmont, Julien, Tsuji, Naomi, Tuffs, Richard, Uchiyama, Yasunobu, van der Walt, Johann, van Eldik, Christopher, van Rensburg, Carlo, van Soelen, Brian, Vasileiadis, George, Veh, Johannes, Venter, Christo, Bony , Mathieu, Vincent, Pascal, Vink, Jacco, Völk, Heinrich J., Wagner, Stefan, Watson, Jason John, Werner, Felix, White, Richard, Wierzcholska, Alicja, Wong, Yu Wun, Yassin, Hend Mahmoud, Breuhaus, Mischa, Yusafzai, Anke, Zacharias, Michael, Zanin, Roberta, Zargaryan, Davit, Zdziarski, Andrzej, Zech, Andreas, Zhu, Sylvia, Zmija, Andreas, Zouari, Samuel, Żywucka, Natalia, Brose, Robert, H. E. S. S. Collaboration, Brun, Francois, Bulik, Tomasz, Bylund, Thomas, Cangemi, Floriane, Caroff, Sami, Casanova, Sabrina, Anguener, Oguzhan, Catalano, Jaqueline, Chambery, Pauline, Chand, Tej Bahadur, Chen, Andrew, Cotter, Garret, Curlo, Malgorzata, Dalgleish, Hannah, Damascene Mbarubucyeye, Jean, Davids, Isak Delberth, Davies, James, Arcaro, Cornelia, Devin, Justine, Djannati-Ataï, Arache, Dmytriev, Anton, Donath, Axel, Doroshenko, Victor, Dreyer, Lente, Du Plessis, Louis, Duffy, Connor, Egberts, Kathrin, Einecke, Sabrina, Armand, Celine, ERNENWEIN, Jean-Pierre, Fegan, Steven, Feijen, Kirsty, Fiasson, Armand, Fichet de Clairfontaine, Gaëtan, Fontaine, Gerard, Frans, Lott, Fuessling, Matthias, Funk, Stefan, Gabici, Stefano, Armstrong, Tom, Gallant, Yves, Giavitto, Gianluca, Giunti, Luca, Glawion, Dorit, Glicenstein, Jean-Francois, Grondin, Marie-Hélène, Hattingh, Sumari, Haupt, Maria, HERMANN, German, Hinton, Jim, Ashkar, Halim, Hofmann, Werner, Hoischen, Clemens, Holch, Tim, Holler, Markus, Horns, Dieter, Huang, Zhi-Qiu, Huber, David, Hörbe, Mario, Jamrozy, Marek, Jankowsky, Felix, Backes, Michael, Joshi, Vikas, JUNG, Ira, Kasai, Eli, Katarzynski, Krzysztof, Katz, Ulì, Khangulyan, Dmitry, Khelifi, Bruno, Klepser, Stefan, Kluzniak, Wlodek, Komin, Nukri, Baghmanyan, Vardan, Konno, Ruslan, Kosack, Karl, Kostiunin, Dmitriy, Kreter, Michael, Kukec Mezek, Gašper, Kundu, Anu, Lamanna, Giovanni, Le Stum, Sébastien, Lemiere, Anne, Lemoine-Goumard, Marianne, Naurois , Mathieu, Bony , Mathieu, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and H.E.S.S.
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Brightness, Astrophysics::High Energy Astrophysical Phenomena, atmosphere [Cherenkov counter], Soft gamma repeater, FOS: Physical sciences, burst [gamma ray], X-ray: burst, Astrophysics, gamma ray: burst, Cherenkov counter: atmosphere, Magnetar, Radio spectrum, Observational evidence, Pulsar, ddc:530, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, burst [X-ray]
Abstract: 37th International Cosmic Ray Conference, ICRC2021, Berlin, Germany - Online, 12 Jul 2021 - 23 Jul 2021; Proceedings of Science / International School for Advanced Studies (ICRC2021), 777 (2021). doi:10.22323/1.395.0777, Fast radio bursts (FRB) are enigmatic powerful single radio pulses with durations of several milliseconds and high brightness temperatures suggesting coherent emission mechanism. For the time being a number of extragalactic FRBs have been detected in the high-frequency radio band including repeating ones. The most plausible explanation for these phenomena is magnetar hyperflares. The first observational evidence of this scenario was obtained in April 2020 when an FRB was detected from the direction of the Galactic magnetar and soft gamma repeater SGR1935+2154. The FRB was preceded with a number of soft gamma-ray bursts observed by Swift-BAT satellite, which triggered the follow-up program of the H.E.S.S. imaging atmospheric Cherenkov telescopes (IACTs). H.E.S.S. has observed SGR1935+2154 over a 2 hour window few hours prior to the FRB detection by STARE2 and CHIME. The observations overlapped with other X-ray bursts from the magnetar detected by INTEGRAL and Swift-BAT, thus providing first observations of a magnetar in a flaring state in the very-high energy domain. We present the analysis of these observations, discuss the obtained results and prospects of the H.E.S.S. follow-up program for soft gamma repeaters and anomalous X-ray pulsars., Published by SISSA, Trieste
Published: 2021
Full Text: View/download PDF

18. Modelling pulsar emission in the high-energy and very-high-energy regimes

Author: Barnard, Monica, Venter, C., Harding, A.K., and 12006653 - Venter, Christo (Supervisor)
Subjects: Fermi Large Area Telescope, Vela pulsar (PSR J0835−4510), Astrophysics::High Energy Astrophysical Phenomena, Magnetic fields, Gamma rays, Pulsars
Abstract: PhD (Space Physics), North-West University, Potchefstroom Campus The Fermi Large Area Telescope has revolutionised the γ-ray pulsar field, increasing the population to over 250 detected pulsars. The majority display spectra with exponential cutoffs in a narrow range around a few GeV. Models predicted cutoffs up to 100 GeV; it was therefore not expected that pulsars would be visible in the very-high-energy (>100 GeV) regime. Subsequent surprise discoveries by ground-based telescopes of pulsed emission from four pulsars above tens of GeV have marked the beginning of a new era, raising important questions about the electrodynamics and local environment of pulsar magnetospheres. I have performed geometric light curve modelling using static, retarded vacuum, and offset polar cap dipole Bfields, in conjunction with standard two-pole caustic and outer gap geometries. I also considered a slot gap E-field associated with the offset polar cap B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Increasing the slot gap E-field by a factor of 100 led to improved light curve fits, as well as curvature radiation reaction at lower altitudes. The overall optimal light curve fit was for the retarded vacuum dipole field and outer gap model. Recent kinetic simulations sparked a debate regarding the emission mechanism of pulsed γ-ray emission from pulsars. Some models invoke curvature radiation, while others assume synchrotron radiation in the current sheet. Detection of the Vela pulsar by H.E.S.S. (20 − 120 GeV) and Fermi provides evidence for a curved spectrum. We posit this to result from curvature radiation via primary particles in the pulsar magnetosphere and current sheet. We present energy-dependent light curves using an extended slot gap and current sheet model and invoking a two-step accelerating E-field as motivated by kinetic simulations. I include a refined calculation of the curvature radius of particle trajectories, impacting the particle transport, predicted light curves, and spectra. The model reproduces the decrease of flux of the first light-curve peak relative to the second one, evolution of the bridge emission, near constant phase positions of peaks, and narrowing of pulses with increasing energy. We can fundamentally explain the first of these trends, since I found that the curvature radii of the particle trajectories in regions where the second γ-ray light curve peak originates are systematically larger than those associated with the first peak, implying a correspondingly larger cutoff for the second peak. An unknown azimuthal dependence of the E-field as well as uncertainty in the precise emission locale preclude a simplistic discrimination of emission mechanisms. Finally, H.E.S.S. recently announced the detection of pulsed emission from the Vela pulsar up to 7 TeV, constraining particle energies to exceed several TeV. I contributed to a paper invoking synchrotron self-Compton emission to model this new radiation component, thus providing a consistent framework to describe the TeV emission from Vela. Doctoral
Published: 2021

19. Detection of new Extreme BL Lac objects with H.E.S.S. and Swift XRT

Author: Noel, Angel Priyana, primary, Abdalla, Hassan, additional, Aharonian, Felix, additional, Ait-Benkhali, Faical, additional, Anguener, Oguzhan, additional, Arcaro, Cornelia, additional, Armand, Celine, additional, Armstrong, Tom, additional, Ashkar, Halim, additional, Backes, Michael, additional, Baghmanyan, Vardan, additional, Barbosa Martins, Victor, additional, Barnacka, Anna, additional, Barnard, Monica, additional, Batzofin, Rowan William, additional, Becherini, Yvonne, additional, Berge, David, additional, Bernloehr, Konrad, additional, Bi, Baiyang, additional, Böttcher, Markus, additional, Boisson, Catherine, additional, Bolmont, Julien, additional, Bony (de), Mathieu, additional, Breuhaus, Mischa, additional, Brose, Robert, additional, Brun, Francois, additional, Bulik, Tomasz, additional, Bylund, Thomas, additional, Cangemi, Floriane, additional, Caroff, Sami, additional, Casanova, Sabrina, additional, Catalano, Jaqueline, additional, Chambery, Pauline, additional, Chand, Tej Bahadur, additional, Chen, Andrew, additional, Cotter, Garret, additional, Curlo, Malgorzata, additional, Dalgleish, Hannah, additional, Damascene Mbarubucyeye, Jean, additional, Davids, Isak Delberth, additional, Davies, James, additional, Devin, Justine, additional, Djannati-Ataï, Arache, additional, Dmytriiev, Anton, additional, Donath, Axel, additional, Doroshenko, Victor, additional, Dreyer, Lente, additional, Du Plessis, Louis, additional, Duffy, Connor, additional, Egberts, Kathrin, additional, Einecke, Sabrina, additional, ERNENWEIN, Jean-Pierre, additional, Fegan, Steven, additional, Feijen, Kirsty, additional, Fiasson, Armand, additional, Fichet de Clairfontaine, Gaëtan, additional, Fontaine, Gerard, additional, Frans, Lott, additional, Fuessling, Matthias, additional, Funk, Stefan, additional, Gabici, Stefano, additional, Gallant, Yves, additional, Giavitto, Gianluca, additional, Giunti, Luca, additional, Glawion, Dorit, additional, Glicenstein, Jean-Francois, additional, Grondin, Marie-Hélène, additional, Hattingh, Sumari, additional, Haupt, Maria, additional, HERMANN, German, additional, Hinton, Jim, additional, Hofmann, Werner, additional, Hoischen, Clemens, additional, Holch, Tim, additional, Holler, Markus, additional, Horns, Dieter, additional, Huang, Zhi-Qiu, additional, Huber, David, additional, Hörbe, Mario, additional, Jamrozy, Marek, additional, Jankowsky, Felix, additional, Joshi, Vikas, additional, JUNG, Ira, additional, Kasai, Eli, additional, Katarzynski, Krzysztof, additional, Katz, Ulì, additional, Khangulyan, Dmitry, additional, Khelifi, Bruno, additional, Klepser, Stefan, additional, Kluzniak, Wlodek, additional, Komin, Nukri, additional, Konno, Ruslan, additional, Kosack, Karl, additional, Kostunin, Dmitriy, additional, Kreter, Michael, additional, Kukec Mezek, Gašper, additional, Kundu, Anu, additional, Lamanna, Giovanni, additional, Le Stum, Sebastien, additional, Lemiere, Anne, additional, Lemoine-Goumard, Marianne, additional, Lenain, Jean-Philippe, additional, Leuschner, Fabian, additional, Levy, Christelle, additional, Lohse, Thomas, additional, Luashvili, Anna, additional, Lypova, Iryna, additional, Mackey, Jonathan, additional, Majumdar, Jhilik, additional, Malyshev, Denys, additional, Malyshev, Dmitry, additional, Marandon, Vincent, additional, Marchegiani, Paolo, additional, Marcowith, Alexandre, additional, Mares, Arnaud, additional, Martí-Devesa, Guillem, additional, Marx, Ramin, additional, Maurin, Gilles, additional, Meintjes, Pieter, additional, Meyer, Manuel, additional, Mitchell, Alison, additional, Moderski, Rafal, additional, Mohrmann, Lars, additional, Montanari, Alessandro, additional, Moore, Chris, additional, Morris, Paul, additional, Moulin, Emmanuel, additional, Muller, Jacques, additional, Murach, Thomas, additional, Nakashima, Kaori, additional, Naurois (de), Mathieu, additional, Nayerhoda, Amid, additional, Davids, Hambeleleni, additional, Niemiec, Jacek, additional, O'Brien, Paul, additional, Oberholzer, Laenita Lorraine, additional, Ohm, Stefan, additional, Olivera-Nieto, Laura, additional, Ona-Wilhelmi (de), Emma, additional, Ostrowski, Michal, additional, Panny, Sebastian, additional, Panter, Michael, additional, Parsons, Dan, additional, Peron, Giada, additional, Pita, Santiago, additional, Poireau, Vincent, additional, Prokhorov, Dmitry A, additional, Prokoph, Heike, additional, PUEHLHOFER, Gerd, additional, Punch, Michael, additional, Quirrenbach, Andreas, additional, Reichherzer, Patrick, additional, Reimer, Anita, additional, Reimer, Olaf, additional, Remy, Quentin, additional, Renaud, Matthieu, additional, Reville, Brian, additional, Rieger, Frank, additional, Romoli, Carlo, additional, Rowell, Gavin P, additional, Rudak, Bronislaw, additional, Rueda Ricarte, Hector, additional, Ruiz Velasco, Edna, additional, Sahakian, Vardan, additional, Sailer, Simon, additional, Salzmann, Heiko, additional, Sanchez, David, additional, Santangelo, Andrea, additional, Sasaki, Manami, additional, Schaefer, Johannes, additional, Schutte, Hester, additional, Schwanke, Ullrich, additional, Schüssler, Fabian, additional, Senniappan, Mohanraj, additional, Seyffert, Albert, additional, Shapopi, Jimmy N.S., additional, Shiningayamwe, Kleopas, additional, Simoni, Rachel, additional, Sinha, Atreyee, additional, Sol, Helene, additional, Spackman, Hugh, additional, Specovius, Andreas, additional, Spencer, Samuel Timothy, additional, Spir-Jacob, Marion, additional, Stawarz, Lukasz, additional, Steenkamp, Riaan, additional, Stegmann, Christian, additional, Steinmassl, Simon, additional, Steppa, Constantin, additional, Sun, Lei, additional, Takahashi, Tadayuki, additional, Tanaka, Takaaki, additional, Tavernier, Thomas, additional, Taylor, Andrew, additional, Terrier, Regis, additional, Thiersen, Hannes, additional, Thorpe-Morgan, Charles, additional, Tluczykont, Martin, additional, Tomankova, Lenka, additional, Tsirou, Michelle, additional, Tsuji, Naomi, additional, Tuffs, Richard, additional, Uchiyama, Yasunobu, additional, van der Walt, Johann, additional, van Eldik, Christopher, additional, van Rensburg, Carlo, additional, van Soelen, Brian, additional, Vasileiadis, George, additional, Veh, Johannes, additional, Venter, Christo, additional, Vincent, Pascal, additional, Vink, Jacco, additional, Völk, Heinrich J., additional, Wagner, Stefan, additional, Watson, Jason John, additional, Werner, Felix, additional, White, Richard, additional, Wierzcholska, Alicja, additional, Wong, Yu Wun, additional, Yassin, Hend Mahmoud, additional, Yusafzai, Anke, additional, Zacharias, Michael, additional, Zanin, Roberta, additional, Zargaryan, Davit, additional, Zdziarski, Andrzej, additional, Zech, Andreas, additional, Zhu, Sylvia, additional, Zmija, Andreas, additional, Zouari, Samuel, additional, and Żywucka, Natalia, additional
Published: 2021
Full Text: View/download PDF

20. Science verification of the new FlashCam-based camera in the 28m telescope of H.E.S.S.

Author: Puehlhofer, Gerd, primary, Bernlöhr, Konrad, additional, Bi, Baiyang, additional, HERMANN, German, additional, Hinton, Jim, additional, Jung-Richardt, Ira, additional, Leuschner, Fabian, additional, Marandon, Vincent, additional, Mitchell, Alison, additional, Mohrmann, Lars, additional, Parsons, Robert Daniel, additional, Sailer, Simon, additional, Salzmann, Heiko, additional, Steinmassl, Simon, additional, Werner, Felix, additional, Abdalla, Hassan, additional, Aharonian, Felix, additional, Ait-Benkhali, Faical, additional, Anguener, Oguzhan, additional, Arcaro, Cornelia, additional, Armand, Celine, additional, Armstrong, Tom, additional, Ashkar, Halim, additional, Backes, Michael, additional, Baghmanyan, Vardan, additional, Barbosa Martins, Victor, additional, Barnacka, Anna, additional, Barnard, Monica, additional, Batzofin, Rowan, additional, Becherini, Yvonne, additional, Berge, David, additional, Bernloehr, Konrad, additional, Böttcher, Markus, additional, Boisson, Catherine, additional, Bolmont, Julien, additional, Bony (de), Mathieu, additional, Breuhaus, Mischa, additional, Brose, Robert, additional, Brun, Francois, additional, Bulik, Tomasz, additional, Bylund, Thomas, additional, Cangemi, Floriane, additional, Caroff, Sami, additional, Casanova, Sabrina, additional, Catalano, Jaqueline, additional, Chambery, Pauline, additional, Chand, Tej Bahadur, additional, Chen, Andrew, additional, Cotter, Garret, additional, Curlo, Malgorzata, additional, Dalgleish, Hannah, additional, Damascene Mbarubucyeye, Jean, additional, Davids, Isak Delberth, additional, Davies, James, additional, Devin, Justine, additional, Djannati-Ataï, Arache, additional, Dmytriev, Anton, additional, Donath, Axel, additional, Doroshenko, Victor, additional, Dreyer, Lente, additional, Du Plessis, Louis, additional, Duffy, Connor, additional, Egberts, Kathrin, additional, Einecke, Sabrina, additional, ERNENWEIN, Jean-Pierre, additional, Fegan, Steven, additional, Feijen, Kirsty, additional, Fiasson, Armand, additional, Fichet de Clairfontaine, Gaëtan, additional, Fontaine, Gerard, additional, Frans, Lott, additional, Fuessling, Matthias, additional, Funk, Stefan, additional, Gabici, Stefano, additional, Gallant, Yves, additional, Giavitto, Gianluca, additional, Giunti, Luca, additional, Glawion, Dorit, additional, Glicenstein, Jean-Francois, additional, Grondin, Marie-Hélène, additional, Hattingh, Sumari, additional, Haupt, Maria, additional, Hörbe, Mario, additional, Hofmann, Werner, additional, Hoischen, Clemens, additional, Holch, Tim, additional, Holler, Markus, additional, Horns, Dieter, additional, Huang, Zhi-Qiu, additional, Huber, David, additional, Jamrozy, Marek, additional, Jankowsky, Felix, additional, Joshi, Vikas, additional, Kasai, Eli, additional, Katarzynski, Krzysztof, additional, Katz, Ulì, additional, Khangulyan, Dmitry, additional, Khelifi, Bruno, additional, Klepser, Stefan, additional, Kluzniak, Wlodek, additional, Komin, Nukri, additional, Konno, Ruslan, additional, Kosack, Karl, additional, Kostunin, Dmitriy, additional, Kreter, Michael, additional, Kukec Mezek, Gašper, additional, Kundu, Anu, additional, Lamanna, Giovanni, additional, Le Stum, Sébastien, additional, Lemiere, Anne, additional, Lemoine-Goumard, Marianne, additional, Lenain, Jean-Philippe, additional, Levy, Christelle, additional, Lohse, Thomas, additional, Luashvili, Anna, additional, Lypova, Iryna, additional, Mackey, Jonathan, additional, Majumdar, Jhilik, additional, Malyshev, Denys, additional, Malyshev, Dmitry, additional, Marchegiani, Paolo, additional, Marcowith, Alexandre, additional, Mares, Arnaud, additional, Martí-Devesa, Guillem, additional, Marx, Ramin, additional, Maurin, Gilles, additional, Meintjes, Pieter, additional, Meyer, Manuel, additional, Moderski, Rafal, additional, Montanari, Alessandro, additional, Moore, Chris, additional, Morris, Paul, additional, Moulin, Emmanuel, additional, Muller, Jacques, additional, Murach, Thomas, additional, Nakashima, Kaori, additional, Naurois (de), Mathieu, additional, Nayerhoda, Amid, additional, Davids, Hambeleleni, additional, Niemiec, Jacek, additional, Noel, Angel, additional, O'Brien, Paul, additional, Oberholzer, Laenita Lorraine, additional, Ohm, Stefan, additional, Olivera-Nieto, Laura, additional, Ona-Wilhelmi (de), Emma, additional, Ostrowski, Michal, additional, Panny, Sebastian, additional, Panter, Michael, additional, Parsons, Dan, additional, Peron, Giada, additional, Pita, Santiago, additional, Poireau, Vincent, additional, Prokhorov, Dmitry, additional, Prokoph, Heike, additional, Punch, Michael, additional, Quirrenbach, Andreas, additional, Reichherzer, Patrick, additional, Reimer, Anita, additional, Reimer, Olaf, additional, Remy, Quentin, additional, Renaud, Matthieu, additional, Reville, Brian, additional, Rieger, Frank, additional, Romoli, Carlo, additional, Rowell, Gavin, additional, Rudak, Bronislaw, additional, Rueda Ricarte, Hector, additional, Ruiz Velasco, Edna, additional, Sahakian, Vardan, additional, Sanchez, David, additional, Santangelo, Andrea, additional, Sasaki, Manami, additional, Schaefer, Johannes, additional, Schüssler, Fabian, additional, Schutte, Hester, additional, Schwanke, Ullrich, additional, Senniappan, Mohanraj, additional, Seyffert, Albert, additional, Shapopi, Jimmy N.S., additional, Shiningayamwe, Kleopas, additional, Simoni, Rachel, additional, Sinha, Atreyee, additional, Sol, Helene, additional, Spackman, Hugh, additional, Specovius, Andreas, additional, Spencer, Samuel Timothy, additional, Spir-Jacob, Marion, additional, Stawarz, Lukasz, additional, Steenkamp, Riaan, additional, Stegmann, Christian, additional, Steppa, Constantin, additional, Sun, Lei, additional, Takahashi, Tadayuki, additional, Tanaka, Takaaki, additional, Tavernier, Thomas, additional, Taylor, Andrew, additional, Terrier, Regis, additional, Thiersen, Hannes, additional, Thorpe-Morgan, Charles, additional, Tluczykont, Martin, additional, Tomankova, Lenka, additional, Tsirou, Michelle, additional, Tsuji, Naomi, additional, Tuffs, Richard, additional, Uchiyama, Yasunobu, additional, van der Walt, Johann, additional, van Eldik, Christopher, additional, van Rensburg, Carlo, additional, van Soelen, Brian, additional, Vasileiadis, George, additional, Veh, Johannes, additional, Venter, Christo, additional, Vincent, Pascal, additional, Vink, Jacco, additional, Völk, Heinrich J., additional, Wagner, Stefan, additional, Watson, Jason John, additional, White, Richard, additional, Wierzcholska, Alicja, additional, Wong, Yu Wun, additional, Yassin, Hend Mahmoud, additional, Yusafzai, Anke, additional, Zacharias, Michael, additional, Zanin, Roberta, additional, Zargaryan, Davit, additional, Zdziarski, Andrzej, additional, Zech, Andreas, additional, Zhu, Sylvia, additional, Zmija, Andreas, additional, Zouari, Samuel, additional, and Żywucka, Natalia, additional
Published: 2021
Full Text: View/download PDF

21. Search for dark matter signals towards a selection of recently detected DES dwarf galaxy satellites of the Milky Way with HESS

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdallah, H., Arcara, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdallah, H., Arcara, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., and H.E.S.S. Collaboration
Abstract: Dwarf spheroidal galaxy satellites of the Milky Way are prime targets for indirect detection of dark matter with gamma rays due to their proximity, high dark matter content, and absence of nonthermal emission processes. Recently, the Dark Energy Survey (DES) revealed the existence of new ultrafaint dwarf spheroidal galaxies in the southern-hemisphere sky, therefore ideally located for ground-based observations with the imaging atmospheric Cherenkov telescope array H.E.S.S. We present a search for very-high-energy ( E ≳ 100 GeV ) gamma-ray emission using H.E.S.S. observations carried out recently towards Reticulum II, Tucana II, Tucana III, Tucana IV, and Grus II satellites. No significant very-high-energy gamma-ray excess is found from the observations on any individual object nor in the combined analysis of all the datasets. Using the most recent modeling of the dark matter distribution in the dwarf galaxy halo, we compute for the first time on DES satellites individual and combined constraints from Cherenkov telescope observations on the annihilation cross section of dark matter particles in the form of Weakly Interacting Massive Particles. The combined 95% C.L. observed upper limits reach ⟨ σ v ⟩ ≃ 1 × 10 − 23 cm 3 s − 1 in the W + W − channel and 4 × 10 − 26 cm 3 s − 1 in the γ γ channels for a dark matter mass of 1.5 TeV. The H.E.S.S. constraints well complement the results from Fermi-LAT, HAWC, MAGIC, and VERITAS and are currently the most stringent in the γ γ channels in the multi-GeV/multi-TeV mass range.
Published: 2020

22. Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., and H.E.S.S. Collaboration
Abstract: We report on the detection of very high energy (VHE; E > 100 GeV) γ-ray emission from the BL Lac objects KUV 00311−1938 and PKS 1440−389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE γ-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311−1938 of z < 0.98 and of PKS 1440−389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311−1938 is constrained to 0.51 ≤ z < 0.98 and of PKS 1440−389 to 0.14 ⪅ z < 0.53
Published: 2020

23. H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, 21106266 - Van Rensburg, Carlo, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiazingh, Z., Zacharias, M., Zywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, 21106266 - Van Rensburg, Carlo, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiazingh, Z., Zacharias, M., Zywucka, N., and H.E.S.S. Collaboration
Abstract: Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E ≥ 100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV–GeV γ-ray flaring activity from the FSRQ PKS 0736+017 (z = 0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the γ-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a γ-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The γ-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The γ-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the γ-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region rBLR with a bulk Lorentz factor Γ ' 20, or at the level of the radius of the dusty torus rtorus with Γ ' 60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z = 0.189 is the nearest so far. The location of the γ-ray emitting region
Published: 2020

24. Probing the magnetic field in the GW170817 outflow using HESS observations

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., and H.E.S.S. Collaboration
Abstract: The detection of the first electromagnetic counterpart to the binary neutron star (BNS) merger remnant GW170817 established the connection between short γ-ray bursts and BNS mergers. It also confirmed the forging of heavy elements in the ejecta (a so-called kilonova) via the r-process nucleosynthesis. The appearance of nonthermal radio and X-ray emission, as well as the brightening, which lasted more than 100 days, were somewhat unexpected. Current theoretical models attempt to explain this temporal behavior as either originating from a relativistic off-axis jet or a kilonova-like outflow. In either scenario, there is some ambiguity regarding how much energy is transported in the nonthermal electrons versus the magnetic field of the emission region. Combining the Very Large Array (radio) and Chandra (X-ray) measurements with observations in the GeV–TeV domain can help break this ambiguity, almost independently of the assumed origin of the emission. Here we report for the first time on deep H.E.S.S. observations of GW170817/GRB 170817A between 124 and 272 days after the BNS merger with the full H.E.S.S. array of telescopes, as well as on an updated analysis of the prompt (<5 days) observations with the upgraded H.E.S.S. phase-I telescopes. We discuss implications of the H.E.S.S. measurement for the magnetic field in the context of different source scenarios
Published: 2020

25. Resolving the Crab pulsar wind nebula at teraelectronvolt energies

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 29092086 - Zacharias, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 29092086 - Zacharias, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and H.E.S.S. Collaboration
Abstract: The Crab nebula is one of the most-studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very-high-energy gamma rays1,2. It is known from observations in the radio to gamma-ray part of the spectrum that the nebula is powered by a pulsar, which converts most of its rotational energy losses into a highly relativistic outflow. This outflow powers a pulsar wind nebula, a region of up to ten light-years across, filled with relativistic electrons and positrons. These particles emit synchrotron photons in the ambient magnetic field and produce very-high-energy gamma rays by Compton up-scattering of ambient low-energy photons. Although the synchrotron morphology of the nebula is well established, it has not been known from which region the very-high-energy gamma rays are emitted3,4,5,6,7,8. Here we report that the Crab nebula has an angular extension at gamma-ray energies of 52 arcseconds (assuming a Gaussian source width), much larger than at X-ray energies. This result closes a gap in the multi-wavelength coverage of the nebula, revealing the emission region of the highest-energy gamma rays. These gamma rays enable us to probe a previously inaccessible electron and positron energy range. We find that simulations of the electromagnetic emission reproduce our measurement, providing a non-trivial test of our understanding of particle acceleration in the Crab nebula
Published: 2020

26. Simultaneous observations of the blazar PKS 2155-304 from ultra-violet to TeV energies

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., H.E.S.S. Collaboration, Fermi LAT, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., H.E.S.S. Collaboration, and Fermi LAT
Abstract: Here we report the results of the first ever contemporaneous multi-wavelength observation campaign on the BL Lac object PKS 2155−304 involving Swift, NuSTAR, Fermi-LAT, and H.E.S.S. The use of these instruments allows us to cover a broad energy range, which is important for disentangling the different radiative mechanisms. The source, observed from June 2013 to October 2013, was found in a low flux state with respect to previous observations but exhibited highly significant flux variability in the X-rays. The high-energy end of the synchrotron spectrum can be traced up to 40 keV without significant contamination by high-energy emission. A one-zone synchrotron self-Compton model was used to reproduce the broadband flux of the source for all the observations presented here but failed for previous observations made in April 2013. A lepto-hadronic solution was then explored to explain these earlier observational results
Published: 2020

27. A very-high-energy component deep in the γ-ray burst afterglow

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, 33379009 - Kreter, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, 33379009 - Kreter, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Kreter, M., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and Zywucka, N.
Abstract: Gamma-ray bursts (GRBs) are brief flashes of γ-rays and are considered to be the most energetic explosive phenomena in the Universe1. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow—produced by the interaction between the ejected matter and the circumburst medium—slows down, and a gradual decrease in brightness is observed2. GRBs typically emit most of their energy via γ-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments3. However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive4. Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow—ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and γ-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies
Published: 2019

28. HESS and Suzaku observations of the Vela X pulsar wind nebula

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 21106266 - Van Rensburg, Carlo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 21106266 - Van Rensburg, Carlo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., and H.E.S.S. Collaboration
Abstract: Context. Pulsar wind nebulae (PWNe) represent the most prominent population of Galactic very-high-energy gamma-ray sources and are thought to be an efficient source of leptonic cosmic rays. Vela X is a nearby middle-aged PWN, which shows bright X-ray and TeV gamma-ray emission towards an elongated structure called the cocoon. Aims. Since TeV emission is likely inverse-Compton emission of electrons, predominantly from interactions with the cosmic microwave background, while X-ray emission is synchrotron radiation of the same electrons, we aim to derive the properties of the relativistic particles and of magnetic fields with minimal modelling. Methods. We used data from the Suzaku XIS to derive the spectra from three compact regions in Vela X covering distances from 0.3 to 4 pc from the pulsar along the cocoon. We obtained gamma-ray spectra of the same regions from H.E.S.S. observations and fitted a radiative model to the multi-wavelength spectra. Results. The TeV electron spectra and magnetic field strengths are consistent within the uncertainties for the three regions, with energy densities of the order 10−12 erg cm−3. The data indicate the presence of a cutoff in the electron spectrum at energies of ~ 100 TeV and a magnetic field strength of ~6 μG. Constraints on the presence of turbulent magnetic fields are weak. Conclusions. The pressure of TeV electrons and magnetic fields in the cocoon is dynamically negligible, requiring the presence of another dominant pressure component to balance the pulsar wind at the termination shock. Sub-TeV electrons cannot completely account for the missing pressure, which may be provided either by relativistic ions or from mixing of the ejecta with the pulsar wind. The electron spectra are consistent with expectations from transport scenarios dominated either by advection via the reverse shock or by diffusion, but for the latter the role of radiative losses near the termination shock needs to be further investigated in the light of t
Published: 2019

29. Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE γ-ray observations with H.E.S.S.

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., and H.E.S.S. Collaboration
Abstract: The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV < E < 100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During two periods of high activity in April 2014 and June 2015 target-of-opportunity observations were undertaken with the High Energy Stereoscopic System (H.E.S.S.) in the very-high-energy (VHE, E > 100 GeV) γ-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8.7σ significance above an energy threshold of 66 GeV. No VHE variability was detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of 4.2 ± 0.3. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole was estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at r ≳ 1.7 × 1017 cm from the black hole, that is beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models were used to describe the evolution of the 2015 flare. Neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data were used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279
Published: 2019

30. Particle transport within the pulsar wind nebula HESS J1825–137

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 30366755 - Chand, Tej B., Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 30366755 - Chand, Tej B., Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and H.E.S.S. Collaboration
Abstract: Context. We present a detailed view of the pulsar wind nebula (PWN) HESS J1825–137. We aim to constrain the mechanisms dominating the particle transport within the nebula, accounting for its anomalously large size and spectral characteristics. Aims. The nebula was studied using a deep exposure from over 12 years of H.E.S.S. I operation, together with data from H.E.S.S. II that improve the low-energy sensitivity. Enhanced energy-dependent morphological and spatially resolved spectral analyses probe the very high energy (VHE, E > 0.1 TeV) γ-ray properties of the nebula. Methods. The nebula emission is revealed to extend out to 1.5° from the pulsar, ~1.5 times farther than previously seen, making HESS J1825–137, with an intrinsic diameter of ~100 pc, potentially the largest γ-ray PWN currently known. Characterising the strongly energy-dependent morphology of the nebula enables us to constrain the particle transport mechanisms. A dependence of the nebula extent with energy of R ∝ Eα with α = −0.29 ± 0.04stat ± 0.05sys disfavours a pure diffusion scenario for particle transport within the nebula. The total γ-ray flux of the nebula above 1 TeV is found to be (1.12 ± 0.03stat ± 0.25sys) × 10−11 cm−2 s−1, corresponding to ~64% of the flux of the Crab nebula. Results. HESS J1825–137 is a PWN with clearly energy-dependent morphology at VHE γ-ray energies. This source is used as a laboratory to investigate particle transport within intermediate-age PWNe. Based on deep observations of this highly spatially extended PWN, we produce a spectral map of the region that provides insights into the spectral variation within the nebula
Published: 2019

31. H.E.S.S. observations of the flaring gravitationally lensed galaxy PKS 1830-211

Author: 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, T.B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, T.B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and H.E.S.S. Collaboration
Abstract: PKS 1830–211 is a known macrolensed quasar located at a redshift of z = 2.5. Its high-energy gamma-ray emission has been detected with the Fermi-Large Area Telescope (LAT) instrument and evidence for lensing was obtained by several authors from its high-energy data. Observations of PKS 1830–211 were taken with the High Energy Stereoscopic System (H.E.S.S.) array of Imaging Atmospheric Cherenkov Telescopes in 2014 August, following a flare alert by the Fermi-LAT Collaboration. The H.E.S.S observations were aimed at detecting a gamma-ray flare delayed by 20–27 d from the alert flare, as expected from observations at other wavelengths. More than 12 h of good-quality data were taken with an analysis threshold of ∼67 GeV. The significance of a potential signal is computed as a function of the date and the average significance over the whole period. Data are compared to simultaneous observations by Fermi-LAT. No photon excess or significant signal is detected. An upper limit on PKS 1830–211 flux above 67 GeV is computed and compared to the extrapolation of the Fermi-LAT flare spectrum
Published: 2019

32. Upper limits on very-high-energy gamma-ray emission from core-collapse supernovae observed with H.E.S.S.

Author: 34208968 - Zywucka-Hejzner, Natalia, 29092086 - Zacharias, Michael, 26594080 - Wadiasingh, Zorawar, 12006653 - Venter, Christo, 21106266 - Van Rensburg, Carlo, 10060499 - Van der Walt, Diederick Johannes, 20126999 - Seyffert, Albertus Stefanus, 22799133 - Schutte, Hester M., 26403366 - Ndiyavala, Hambeleleni, 31125417 - Chandra, Sunil, 30366755 - Chand, Tej B., 24420530 - Böttcher, Markus, 20574266 - Barnard, Monica, 28644743 - Backes, Michael, 30588766 - Arcaro, Cornelia, 26598973 - Abdalla, Hassan, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., H.E.S.S. Collaboration, 34208968 - Zywucka-Hejzner, Natalia, 29092086 - Zacharias, Michael, 26594080 - Wadiasingh, Zorawar, 12006653 - Venter, Christo, 21106266 - Van Rensburg, Carlo, 10060499 - Van der Walt, Diederick Johannes, 20126999 - Seyffert, Albertus Stefanus, 22799133 - Schutte, Hester M., 26403366 - Ndiyavala, Hambeleleni, 31125417 - Chandra, Sunil, 30366755 - Chand, Tej B., 24420530 - Böttcher, Markus, 20574266 - Barnard, Monica, 28644743 - Backes, Michael, 30588766 - Arcaro, Cornelia, 26598973 - Abdalla, Hassan, Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Zywucka, N., and H.E.S.S. Collaboration
Abstract: Young core-collapse supernovae with dense-wind progenitors may be able to accelerate cosmic-ray hadrons beyond the knee of the cosmic-ray spectrum, and this may result in measurable gamma-ray emission. We searched for gamma-ray emission from ten supernovae observed with the High Energy Stereoscopic System (H.E.S.S.) within a year of the supernova event. Nine supernovae were observed serendipitously in the H.E.S.S. data collected between December 2003 and December 2014, with exposure times ranging from 1.4 to 53 h. In addition we observed SN 2016adj as a target of opportunity in February 2016 for 13 h. No significant gamma-ray emission has been detected for any of the objects, and upper limits on the >1 TeV gamma-ray flux of the order of ~10−13 cm−2s−1 are established, corresponding to upper limits on the luminosities in the range ~2 × 1039 to ~1 × 1042 erg s−1. These values are used to place model-dependent constraints on the mass-loss rates of the progenitor stars, implying upper limits between ~2 × 10−5 and ~2 × 10−3 M⊙ yr−1 under reasonable assumptions on the particle acceleration parameters
Published: 2019

33. ?The starburst galaxy NGC 253 revisited by H.E.S.S. and Fermi–Lat

Author: Hassan, Hamad Hassan Abdalla, Arcaro, Cornelia, Backes, Mivhael, Barnard, Monica, Boettcher, Markus, Sunil, Chandra, Garrigoux, Tania, Ndiyavala, Hambeleneni, Seyffert, Albertus Stefanus, Spanier, Felix Alexander, Sushch, Iurii, Van Der Walt, Diederick Johannes, Van Rensburg, Carlo, Venter, Christo, Wadiasingh, Zorawar, Zacharias, Michael, Aharonian, F., Ait, Benkhali, Anguner, E., Arakawa, M., Armand, C., Arrieta, M., Backes, M., Becherini, Y., Becker, Tjus, Berge, D., Et, Al (and 207 Others), and 30588766 – Arcaro, Cornelia
Abstract: NWU NatAgric Sciences: Research & Innovation
Published: 2018

34. First ground–based measurement of sub–20 GeV to 100 GeV ?–Rays from the Vela pulsar with H.E.S.S. II

Author: Hassan, Hamad Hassan Abdalla, Arcaro, Cornelia, Backes, Mivhael, Barnard, Monica, Boettcher, Markus, Sunil, Chandra, Kr?ger, Petrus Paulus, Ndiyavala, Hambeleneni, Seyffert, Albertus Stefanus, Spanier, Felix Alexander, Van Der Walt, Diederick Johannes, Van Rensburg, Carlo, Venter, Christo, Wadiasingh, Zorawar, Zacharias, Michael, Aharonian, F., Ait, Benkhali, Anguner, E., Arakawa, M., Armand, C., Arrieta, M., Becherini, Y., Becker, Tjus, Berge, D., Bernhard, S., Et, Al (and 208 Others), and 30588766 – Arcaro, Cornelia
Abstract: NWU NatAgric Sciences: Research & Innovation
Published: 2018

35. Multi-TeV Emission from the Vela Pulsar

Author: Harding, Alice K., primary, Kalapotharakos, Constantinos, additional, Barnard, Monica, additional, and Venter, Christo, additional
Published: 2018
Full Text: View/download PDF

36. Modelling energy-dependent pulsar light curves due to curvature radiation

Author: Barnard, Monica, primary, Venter, Christo, additional, Harding, Alice K., additional, and Kalapotharakos, Constantinos, additional
Published: 2018
Full Text: View/download PDF

37. Detection of variable VHE γ-ray emission from the extra-galactic γ-ray binary LMC P3

Author: 24420530 - Böttcher, Markus, 26909995 - Garrigoux, Tania, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 26403366 - Ndiyavala, Hambeleleni, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 24922986 - Sushch, Iurii, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 20574266 - Barnard, Monica, 26598973 - Abdalla, Hassan, Abdalla, H., Barnard, M., Böttcher, M., Garrigoux, T., Ivascenko, A., Krüger, P.P., Ndiyavala, H., Pekeur, N.W., Seyffert, A.S., Spanier, F., Sushch, I., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., H.E.S.S. Collaboration, 24420530 - Böttcher, Markus, 26909995 - Garrigoux, Tania, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 26403366 - Ndiyavala, Hambeleleni, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 24922986 - Sushch, Iurii, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 20574266 - Barnard, Monica, 26598973 - Abdalla, Hassan, Abdalla, H., Barnard, M., Böttcher, M., Garrigoux, T., Ivascenko, A., Krüger, P.P., Ndiyavala, H., Pekeur, N.W., Seyffert, A.S., Spanier, F., Sushch, I., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and H.E.S.S. Collaboration
Abstract: Context. Recently, the high-energy (HE, 0.1–100 GeV) γ-ray emission from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered to be modulated with a 10.3-day period, making it the first extra-galactic γ-ray binary. Aim. This work aims at the detection of very-high-energy (VHE, >100 GeV) γ-ray emission and the search for modulation of the VHE signal with the orbital period of the binary system. Methods. LMC P3 has been observed with the High Energy Stereoscopic System (H.E.S.S.); the acceptance-corrected exposure time is 100 h. The data set has been folded with the known orbital period of the system in order to test for variability of the emission. Results. VHE γ-ray emission is detected with a statistical significance of 6.4 σ. The data clearly show variability which is phase-locked to the orbital period of the system. Periodicity cannot be deduced from the H.E.S.S. data set alone. The orbit-averaged luminosity in the 1–10 TeV energy range is (1.4 ± 0.2) × 1035 erg s−1. A luminosity of (5 ± 1) × 1035 erg s−1 is reached during 20% of the orbit. HE and VHE γ-ray emissions are anti-correlated. LMC P3 is the most luminous γ-ray binary known so far
Published: 2018

38. Modelling energy-dependent pulsar light curves

Author: Venter, Christo, primary, Barnard, Monica, additional, Harding, Alice K., additional, and Kalapotharakos, Constantinos, additional
Published: 2017
Full Text: View/download PDF

39. High-energy pulsar light curves in an offset polar cap B-field geometry

Author: Barnard, Monica, primary, Venter, Christo, additional, and Harding, Alice Kust, additional
Published: 2017
Full Text: View/download PDF

40. TeV gamma-ray observations of the binary neutron star merger GW170817 with H.E.S.S.

Author: 24420530 - Böttcher, Markus, 26909995 - Garrigoux, Tania, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 24922986 - Sushch, Iurii, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 26403366 - Ndiyavala, Hambeleleni, 26598973 - Abdalla, Hassan, 20574266 - Barnard, Monica, Abdalla, H., Barnard, M., Böttcher, M., Garrigoux, T., Ivascenko, A., Krüger, P.P., Ndiyavala, H., Pekeur, N.W., Seyffert, A.S., Spanier, F., Sushch, I., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., H.E.S.S. Collaboration, 24420530 - Böttcher, Markus, 26909995 - Garrigoux, Tania, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 24922986 - Sushch, Iurii, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 26403366 - Ndiyavala, Hambeleleni, 26598973 - Abdalla, Hassan, 20574266 - Barnard, Monica, Abdalla, H., Barnard, M., Böttcher, M., Garrigoux, T., Ivascenko, A., Krüger, P.P., Ndiyavala, H., Pekeur, N.W., Seyffert, A.S., Spanier, F., Sushch, I., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., and H.E.S.S. Collaboration
Abstract: We search for high-energy gamma-ray emission from the binary neutron star merger GW170817 with the H.E.S.S. Imaging Air Cherenkov Telescopes. The observations presented here have been obtained starting only 5.3 hr after GW170817. The H.E.S.S. target selection identified regions of high probability to find a counterpart of the gravitational-wave event. The first of these regions contained the counterpart SSS17a that has been identified in the optical range several hours after our observations. We can therefore present the first data obtained by a groundbased pointing instrument on this object. A subsequent monitoring campaign with the H.E.S.S. telescopes extended over several days, covering timescales from 0.22 to 5.2 days and energy ranges between 270 GeV to 8.55 TeV. No significant gamma-ray emission has been found. The derived upper limits on the very-high-energy gamma-ray flux for the first time constrain non-thermal, high-energy emission following the merger of a confirmed binary neutron star system
Published: 2017

41. Search for dark matter annihilations towards the inner Galactic halo from 10 years of observations with H.E.S.S.

Author: 24420530 - Böttcher, Markus, 13146629 - Davids, Isak Delberth, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26909995 - Garrigoux, Tania, 20574266 - Barnard, Monica, 26598973 - Abdalla, Hassan, Abdallah, H., Barnard, M., Böttcher, M., Davids, I.D., Garrigoux, T., Ivascenko, A., Krüger, P.P., Pekeur, N.W., Seyffert, A.S., Spanier, F., Van der Walt, D.J., Venter, C., H.E.S.S. Collaboration, 24420530 - Böttcher, Markus, 13146629 - Davids, Isak Delberth, 24790052 - Ivascenko, Alex, 11749903 - Krüger, Petrus Paulus, 22050574 - Pekeur, Nicolette Whilna, 20126999 - Seyffert, Albertus Stefanus, 25161814 - Spanier, Felix Alexander, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26909995 - Garrigoux, Tania, 20574266 - Barnard, Monica, 26598973 - Abdalla, Hassan, Abdallah, H., Barnard, M., Böttcher, M., Davids, I.D., Garrigoux, T., Ivascenko, A., Krüger, P.P., Pekeur, N.W., Seyffert, A.S., Spanier, F., Van der Walt, D.J., Venter, C., and H.E.S.S. Collaboration
Abstract: The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using γ-ray observations towards the inner 300 parsecs of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant γ-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section ⟨σv⟩. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach ⟨σv⟩ values of 6×10−26cm3s−1 in the W+W− channel for a DM particle mass of 1.5 TeV, and 2×10−26cm3s−1 in the τ+τ− channel for 1 TeV mass. For the first time, ground-based γ-ray observations have reached sufficient sensitivity to probe ⟨σv⟩ values expected from the thermal relic density for TeV DM particles
Published: 2016

42. Pulsar emission in the very high energy regime

Author: Barnard, Monica, primary, Venter, Christo, additional, and Harding, Alice Kust, additional
Published: 2016
Full Text: View/download PDF

43. Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance

Author: Johan Bregeon, J. Devin, D. Gottschall, Zorawar Wadiasingh, Tadayuki Takahashi, R. J. White, Łukasz Stawarz, V. Barbosa Martins, H.M. Schutte, Maria Haupt, Thomas Lohse, Victor Doroshenko, Domenico Tiziani, M. Lemoine-Goumard, C. Arcaro, Michal Ostrowski, J.-P. Lenain, M. Panter, U. Katz, Michael Kreter, Jim Hinton, A. Lemiere, F. Eichhorn, M. de Naurois, R. Adam, Stefan Ohm, James Davies, Stefan Funk, Alicja Wierzcholska, Michael Punch, S. Sailer, Dmitry Khangulyan, D. A. Sanchez, H. Abdalla, M. Zacharias, M. A. Kastendieck, Stefano Gabici, T. Vuillaume, Rafal Moderski, R. J. Tuffs, N. Shafi, Natalia Żywucka, A. Fiasson, Samuel Timothy Spencer, M. Spir-Jacob, M. Seglar-Arroyo, Alexandre Marcowith, A. Santangelo, V. Baghmanyan, Nu. Komin, T. Chand, Jhilik Majumdar, J. Dyks, V. Joshi, P. deWilt, F. Ait Benkhali, L. Oakes, J. Bolmont, Mischa Breuhaus, Heike Prokoph, E. O. Angüner, G. Lamanna, Anton Dmytriiev, Davit Zargaryan, Ruizhi Yang, Q. Piel, Dmitriy Kostunin, Krzysztof Katarzynski, Catherine Boisson, Axel Donath, A. W. Chen, S. Caroff, V. Sahakian, F. Werner, G. Pühlhofer, Arnaud Mares, D. Jankowsky, R. Marx, M. Füßling, S. Schwemmer, Q. Remy, R. Rauth, Dieter Horns, G. Maurin, Y. A. Gallant, Marek Jamrozy, Clemens Hoischen, A. A. Zdziarski, A.S. Seyffert, R. Konno, M. Barnard, S. Nakashima, Anna Barnacka, Gavin Rowell, M. Mohamed, Riaan Steenkamp, M. Bryan, Helene Sol, A. Carosi, M. Hörbe, Sylvia Zhu, P. J. Meintjes, Michelle Tsirou, Christian Stegmann, Stefan Wagner, E. de Oña Wilhelmi, D. Malyshev, S. Raab, Yasunobu Uchiyama, J. Zorn, L. Rinchiuso, Isak Delberth Davids, Kirsty Feijen, Frank M. Rieger, Pierre Brun, R. D. Parsons, T. Tavernier, Jean-Pierre Ernenwein, I. Jung-Richardt, Jason John Watson, Roberta Zanin, L. Mohrmann, V. Poireau, Gianluca Giavitto, C. van Rensburg, S. Pita, Johannes Veh, K. Bernlöhr, H. Yoneda, Paolo Marchegiani, M. Tluczykont, D. J. van der Walt, A. Djannati-Ataï, Francois Brun, P. Vincent, Markus Holler, Misao Sasaki, Felix Jankowsky, Jacek Niemiec, V. Marandon, C. Trichard, H. Odaka, Felix Aharonian, Olaf Reimer, S. Bonnefoy, Constantin Steppa, Garret Cotter, Celine Armand, Michael Backes, E. Ruiz-Velasco, Thomas Bylund, D. Huber, M.-H. Grondin, Tim Holch, E. Leser, Thomas Murach, Joachim Hahn, J. Muller, G. Hermann, Regis Terrier, D. A. Prokhorov, K. Kosack, C. Levy, Ullrich Schwanke, Naomi Tsuji, Carlo Romoli, Angel Noel, Jonathan Mackey, D. Berge, Gerard Fontaine, B. Peyaud, Iryna Lypova, S. Chandra, L. Giunti, M. Katsuragawa, Yvonne Becherini, C. Moore, Dorit Glawion, K. Egberts, E. Moulin, A. Reimer, Tomasz Bulik, Halim Ashkar, Andreas Quirrenbach, M. Böttcher, Paul J. Morris, Kleopas Shiningayamwe, P. T. O'Brien, Lenka Tomankova, C. van Eldik, L. Dirson, J. F. Glicenstein, Tom Armstrong, Matteo Cerruti, H. Ndiyavala, B. van Soelen, B. Rudak, F. Schüssler, Werner Hofmann, M. Büchele, S. J. Fegan, F. Niederwanger, Bruno Khelifi, Jacco Vink, Sabrina Casanova, M. Curyło, Rachel Simoni, Masanori Arakawa, M. Scalici, G. Martí-Devesa, H. Iwasaki, G. Vasileiadis, Włodek Kluźniak, Christoph Deil, Mohanraj Senniappan, G. Emery, S. Saito, Armelle Jardin-Blicq, K. Nakashima, Heinrich J. Völk, M. Renaud, A. Sinha, Christo Venter, A. Zech, A.M. Taylor, Andreas Specovius, Stefan Klepser, Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), H.E.S.S., German Research Foundation, Alexander von Humboldt Foundation, Centre National de la Recherche Scientifique (France), Japan Society for the Promotion of Science, Science and Technology Facilities Council (UK), Fundación 'la Caixa', National Aeronautics and Space Administration (US), H.E.S.S. Collaboration, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, and 34208968 - Zywucka-Hejzner, Natalia
Subjects: individual [BL Lacertae objects], Swift Gamma-Ray Burst Mission, VHE [gamma ray], satellite, Resolved and unresolved sources as a function of wavelength, Astrophysics, 01 natural sciences, GLAST, blazar, high-redshift [Galaxies], galaxies: high-redshift, 5/3, HESS, 0103 physical sciences, Atom, High Energy Stereoscopic System, Spectroscopy, Blazar, 010303 astronomy & astrophysics, BL Lacertae objects: individual, Astroparticle physics, Physics, general [Gamma-rays], energy: high, 010308 nuclear & particles physics, Astronomy and Astrophysics, gamma-rays: general, redshift, Redshift, gamma ray: VHE, 13. Climate action, Space and Planetary Science, ddc:520, high [energy], HESS - Abteilung Hinton, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Fermi Gamma-ray Space Telescope
Abstract: H.E.S.S. Collaboration: et al., We report on the detection of very high energy (VHE; E > 100 GeV) γ-ray emission from the BL Lac objects KUV 00311−1938 and PKS 1440−389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE γ-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311−1938 of z < 0.98 and of PKS 1440−389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311−1938 is constrained to 0.51 ≤ z < 0.98 and of PKS 1440−389 to 0.14 ⪅ z < 0.53., The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), the U.K. Science and Technology Facilities Council (STFC), the Knut and Alice Wallenberg Foundation, the National Science Centre, Poland grant no. 2016/22/M/ST9/00382, the South African Department of Science and Technology and National Research Foundation, the University of Namibia, the National Commission on Research, Science and Technology of Namibia (NCRST), the Austrian Federal Ministry of Education, Science and Research and the Austrian Science Fund (FWF), the Australian Research Council (ARC), the Japan Society for the Promotion of Science, and the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Zeuthen, Heidelberg, Palaiseau, Paris, Saclay, Tubingen, and in Namibia in the construction and operation of the equipment. This work benefited from services provided by the H.E.S.S. Virtual Organisation, supported by the national resource providers of the EGI Federation. The H.E.S.S. and Fermi/LAT analysis computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at Lunarc. Tomas Bylund and Yvonne Becherini wish to acknowledge the support of the Data Intensive Sciences and Applications (DISA) centre at Linnaeus University. Matteo Cerruti has received financial support through the Postdoctoral Junior Leader Fellowship Programme from “la Caixa” Foundation (LCF/BQ/PI18/11630012). This research made use of the NASA/IPAC Extragalactic Database (NED) and of the SIMBAD Astronomical Database, of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. We acknowledge the use of public data from the Swift data archive. This research made use of Gammapy, a community- developed core Python package for gamma-ray astronomy (Deil et al. 2017). This research has made use of data and software provided by the Fermi Science Support Center, managed by the HEASARC at the Goddard Space Flight Center. Part of this work is based on archival data, software or online services provided by the Space Science Data Center - ASI. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France (doi:10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. This research has made use of the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology.
Published: 2020
Full Text: View/download PDF

44. Probing the Magnetic Field in the GW170817 Outflow Using H.E.S.S. Observations

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Ang��ner, E. O., Arakawa, M., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Barbosa-Martins, V., Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernl��hr, K., Blackwell, R., B��ttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., B��chele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Cotter, G., Cury��o, M., Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ata��, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dyks, J., Egberts, K., Eichhorn, F., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., F��ling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., H��rbe, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kastendieck, M. A., Katarzy��ski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Kh��lifi, B., Klepser, S., Klu��niak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemi��re, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Mart��-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, S., Nakashima, K., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Parsons, R. D., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., P��hlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schlickeiser, R., Sch��ssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, ��., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., V��lk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zorn, J., Zywucka, N., Rodrigues, X., North-West University [Potchefstroom] (NWU), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Max-Planck-Institut für Kernphysik (MPIK), Max-Planck-Gesellschaft, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Rikkyo University [Tokyo], Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), University of Oxford [Oxford], Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, H.E.S.S., Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), H. E. S. S. Collaboration, Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: emission [X-ray], electron, neutron star: binary, 010504 meteorology & atmospheric sciences, magnetic field, Astrophysics, binary [neutron star], Kilonova, 01 natural sciences, HESS, 010303 astronomy & astrophysics, Stellar evolution, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), radio wave, nucleosynthesis, r-process, Gamma-ray bursts, Astrophysics - High Energy Astrophysical Phenomena, Radio wave, Ejecta, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, burst [gamma ray], Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, gamma ray: burst, Gamma-ray transient sources, 0103 physical sciences, Stellar mergers, X-ray: emission, High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Gamma-ray astronomy, Gravitational wave, gravitational radiation, Astronomy and Astrophysics, Neutron star, electromagnetic, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], HESS - Abteilung Hinton, ddc:520, Gamma-ray burst, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: The astrophysical journal / 1 894(2), 1-5 (2020). doi:10.3847/2041-8213/ab8b59, The detection of the first electromagnetic counterpart to the binary neutron star (BNS) merger remnant GW170817 established the connection between short $γ$-ray bursts and BNS mergers. It also confirmed the forging of heavy elements in the ejecta (a so-called kilonova) via the r-process nucleosynthesis. The appearance of nonthermal radio and X-ray emission, as well as the brightening, which lasted more than 100 days, were somewhat unexpected. Current theoretical models attempt to explain this temporal behavior as either originating from a relativistic off-axis jet or a kilonova-like outflow. In either scenario, there is some ambiguity regarding how much energy is transported in the nonthermal electrons versus the magnetic field of the emission region. Combining the Very Large Array (radio) and Chandra (X-ray) measurements with observations in the GeV–TeV domain can help break this ambiguity, almost independently of the assumed origin of the emission. Here we report for the first time on deep H.E.S.S. observations of GW170817/GRB 170817A between 124 and 272 days after the BNS merger with the full H.E.S.S. array of telescopes, as well as on an updated analysis of the prompt (, Published by Institute of Physics Publ., London
Published: 2020
Full Text: View/download PDF

45. Simultaneous observations of the blazar PKS 2155-304 from ultra-violet to TeV energies

Author: Abdalla, H., Adam, R., Barbosa Martins, V., Lenain, J.-P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Barnard, M., Mares, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Becherini, Y., Moore, C., Moulin, E., Muller, J., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., Berge, D., O'Brien, P., Odaka, H., Ohm, S., de Ona Wilhelmi, E., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P.-O., Bernlohr, K., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Priyana Noel, A., Prokhorov, D. A., Prokoph, H., Puhlhofer, G., Punch, M., Quirrenbach, A., Blackwell, R., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Bottcher, M., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schussler, F., Boisson, C., Schulz, A., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Bolmont, J., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Bonnefoy, S., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., Aharonian, F., Bregeon, J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Volk, H. J., Vuillaume, T., Breuhaus, M., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Brun, F., Zorn, J., Zywucka, N., Madejski, G. M., Nalewajko, K., Madsen, K. K., Chiang, J., Balokovic, M., Paneque, D., Furniss, A. K., Hayashida, M., Brun, P., Urry, C. M., Ajello, M., Harrison, F. A., Giebels, B., Stern, D., Forster, K., Giommi, P., Perri, M., Puccetti, S., Zoglauer, A., Bryan, M., Tagliaferri, G., H. E. S. S. Collaboration, NuSTAR Collaboration, Fermi-LAT Collaboration, Swift Collaboration, Buchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Ait Benkhali, F., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Colafrancesco, S., Curyło, M., Davids, I. D., Deil, C., Devin, J., Anguner, E. O., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dyks, J., Egberts, K., Emery, G., Ernenwein, J.-P., Arakawa, M., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Fußling, M., Gabici, S., Gallant, Y. A., Gaté, F., Arcaro, C., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M.-H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Armand, C., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Ashkar, H., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khelifi, B., Backes, M., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemiere, A., Lemoine-Goumard, M., North-West University [Potchefstroom] (NWU), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Kernphysik (MPIK), Max-Planck-Gesellschaft, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Deutsches Elektronen-Synchrotron [Zeuthen] (DESY), Helmholtz-Gemeinschaft = Helmholtz Association, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut für Astronomie und Astrophysik [Tübingen] (IAAT), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, University of Potsdam, Universität Innsbruck [Innsbruck], Universität Zürich [Zürich] = University of Zurich (UZH), Universität Heidelberg [Heidelberg] = Heidelberg University, Centre d'Etudes et de Recherches Comparées sur la Création (CERCC - EA1633), École normale supérieure de Lyon (ENS de Lyon), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Kavli Institute for the Physics and Mathematics of the Universe [Tokyo] (Kavli IPMU), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo), Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Agenzia Spaziale Italiana (ASI), INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), H.E.S.S. Collaboration (e-mail: contact.hess@hess-experiment.eu), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....]), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Universität Heidelberg [Heidelberg], École normale supérieure - Lyon (ENS Lyon), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, and H.E.S.S. Collaboration
Subjects: Astrophysics::High Energy Astrophysical Phenomena, individual: PKS 2155−304 [BL Lacertae objects], Flux, Ultra violet, BL Lacertae objects: individual: PKS 2155-304, FOS: Physical sciences, Astrophysics, BL Lacertae objects: individual: PKS 2155−304, 7. Clean energy, 01 natural sciences, GLAST, law.invention, blazar, X-ray, law, HESS, 0103 physical sciences, synchrotron, ultraviolet, Radiative transfer, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Blazar, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astronomy and Astrophysics, Synchrotron, flux, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], astroparticle physics, HESS - Abteilung Hinton, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], BL Lac object
Abstract: The results of the first ever contemporaneous multi-wavelength observation campaign on the BL Lac object PKS2155-304 involving Swift, NuSTAR, Fermi-LAT and H.E.S.S. are reported. The use of these instruments allows us to cover a broad energy range, important for disentangling the different radiative mechanisms. The source, observed from June 2013 to October 2013, was found in a low flux state with respect to previous observations but exhibited highly significant flux variability in the X-rays. The high-energy end of the synchrotron spectrum can be traced up to 40 keV without significant contamination by high-energy emission. A one-zone synchrotron self-Compton model was used to reproduce the broadband flux of the source for all the observations presented here but failed for previous observations made in April 2013. A lepto-hadronic solution was then explored to explain these earlier observational results., Comment: 15 pages, 4 figures
Published: 2020
Full Text: View/download PDF

46. Resolving acceleration to very high energies along the jet of Centaurus A

Author: Abdalla, H., Arcaro, C., Backes, M., Barnard, M., Böttcher, M., Chand, T., Chandra, S., Ndiyavala, H., Schutte, H.M., Seyffert, A.S., Van der Walt, D.J., Van Rensburg, C., Venter, C., Wadiasingh, Z., Zacharias, M., Żywucka, N., H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, and 34208968 - Zywucka-Hejzner, Natalia
Subjects: High-energy astrophysics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact astrophysical objects
Abstract: The nearby radio galaxy Centaurus A belongs to a class of active galaxies that are luminous at radio wavelengths. Most show collimated relativistic outflows known as jets, which extend over hundreds of thousands of parsecs for the most powerful sources. Accretion of matter onto the central supermassive black hole is believed to fuel these jets and power their emission1. Synchrotron radiation from relativistic electrons causes the radio emission, and it has been suggested that the X-ray emission from Centaurus A also originates in electron synchrotron processes2,3,4. Another possible explanation is inverse Compton scattering with cosmic microwave background (CMB) soft photons5,6,7. Synchrotron radiation needs ultrarelativistic electrons (about 50 teraelectronvolts) and, given their short cooling times, requires some continuous re-acceleration mechanism8. Inverse Compton scattering, on the other hand, does not require very energetic electrons, but the jets must stay highly relativistic on large scales (exceeding 1 megaparsec). Some recent evidence disfavours inverse Compton-CMB models9,10,11,12, although other work seems to be compatible with them13,14. In principle, the detection of extended γ-ray emission, which directly probes the presence of ultrarelativistic electrons, could distinguish between these options. At gigaelectronvolt energies there is also an unusual spectral hardening15,16 in Centaurus A that has not yet been explained. Here we report observations of Centaurus A at teraelectronvolt energies that resolve its large-scale jet. We interpret the data as evidence for the acceleration of ultrarelativistic electrons in the jet, and favour the synchrotron explanation for the X-rays. Given that this jet is not exceptional in terms of power, length or speed, it is possible that ultrarelativistic electrons are commonplace in the large-scale jets of radio-loud active galaxies Correction: In the print version of this Article, M. Holler, M. de Naurois, F. Rieger, D. A. Sanchez and A. M. Taylor should have been indicated as corresponding authors in the author list, all with email address contact.hess@hess-experiment.eu. Additionally, the line ‘Correspondence and requests for materials should be addressed to M.H., M.d.N., F.R., D.A.S. or A.M.T.’ should have been included at the end of the paper. The Article is correct online. (Nature, vol 583, pageE23(2020))
Published: 2020

47. H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Colafrancesco, S., Curylo, M., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kraus, M., Lamanna, G., Lau, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Mares, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Muller, J., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Oña, Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, L., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Zywucka, N., Smith, P. S., Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Deutsches Elektronen-Synchrotron [Zeuthen] (DESY), Helmholtz-Gemeinschaft = Helmholtz Association, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo (UTokyo), Max-Planck-Institut für Kernphysik (MPIK), Max-Planck-Gesellschaft, H.E.S.S. Collaboration, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, 21106266 - Van Rensburg, Carlo, H. E. S. S. Collaboration, University of Namibia, Federal Ministry of Education and Research (Germany), Max Planck Society, German Research Foundation, Helmholtz Association, Alexander von Humboldt Foundation, Ministre de l'Enseignement Supérieur, de la Recherche et de l'Innovation (France), Centre National de la Recherche Scientifique (France), Commissariat à l'Ènergie Atomique et aux Ènergies Alternatives (France), Science and Technology Facilities Council (UK), Knut and Alice Wallenberg Foundation, National Science Centre (Poland), Department of Science and Technology (South Africa), National Research Foundation (South Africa), National Commission on Research Science and Technology (Namibia), Federal Ministry of Education, Science and Research (Austria), Austrian Science Fund, Australian Research Council, Japan Society for the Promotion of Science, University of Amsterdam, La Caixa, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Helmholtz-Gemeinschaft, Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2)
Subjects: quasars: individual: PKS 0736+017, VHE [gamma ray], torus, Astrophysics, 01 natural sciences, law.invention, Raigs gamma, Observatory, law, HESS, optical, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, relativistic processes, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), photon, collimator, Relativistic processes, Gamma ray, Particle physics, observatory, Lorentz factor, astroparticle physics, symbols, Astrophysics - High Energy Astrophysical Phenomena, Lorentz, Flare, Astrophysics::High Energy Astrophysical Phenomena, general [Gamma rays], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, GLAST, Telescope, symbols.namesake, emission [gamma ray], 0103 physical sciences, quasar, Quasars, Cherenkov radiation, Quàsars, 010308 nuclear & particles physics, Gamma rays, opacity, Astronomy and Astrophysics, Quasar, gamma rays: general, doubling, individual: PKS 0736+017 [Quasars], flux, monitoring, Cherenkov counter, 13. Climate action, Space and Planetary Science, ddc:520, HESS - Abteilung Hinton, Astroparticle physics, Física de partícules, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Fermi Gamma-ray Space Telescope
Abstract: [Context] Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E 100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects., [Aims] Following the detection of MeV–GeV γ-ray flaring activity from the FSRQ PKS 0736+017 (z = 0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the γ-ray emission in the VHE band., [Methods] H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes., [Results] VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a γ-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The γ-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The γ-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the γ-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region rBLR with a bulk Lorentz factor Γ ≃ 20, or at the level of the radius of the dusty torus rtorus with Γ ≃ 60., [Conclusions] PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z = 0.189 is the nearest so far. The location of the γ-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments., The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat à l’énergie atomique et aux énergies alternatives (CEA), the UK Science and Technology Facilities Council (STFC), the Knut and Alice Wallenberg Foundation, the National Science Centre, Poland grant no. 2016/22/M/ST9/00382, the South African Department of Science and Technology and National Research Foundation, the University of Namibia, the National Commission on Research, Science and Technology of Namibia (NCRST), the Austrian Federal Ministry of Education, Science and Research and the Austrian Science Fund (FWF), the Australian Research Council (ARC), the Japan Society for the Promotion of Science and by the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Zeuthen, Heidelberg, Palaiseau, Paris, Saclay, Tübingen and in Namibia in the construction and operation of the equipment. This work benefited from services provided by the H.E.S.S. Virtual Organisation, supported by the national resource providers of the EGI Federation. The CC-IN2P3 (cc.in2p3.fr) is gratefully acknowledged for providing a significant amount of the computing resources and services needed for this work. Part of this work is based on archival data, software or online services provided by the Space Science Data Center – ASI. Blazar observations at Steward Observatory are funded though NASA/Fermi Guest Investigator Program grant NNX15AU81G. Matteo Cerruti has received financial support through the Postdoctoral Junior Leader Fellowship Programme from la Caixa Banking Foundation (LCF/BQ/PI18/11630012). The authors would like to thank the anonymous referee, whose constructive comments significantly improved the manuscript.
Published: 2020
Full Text: View/download PDF

48. H.E.S.S. and Fermi-LAT observations of PSR B1259-63/LS 2883 during its 2014 and 2017 periastron passages

Author: Lars Mohrmann, J. Dyks, M. Zacharias, C. Armand, D. Tiziani, V. Poireau, F. Ait Benkhali, M. Panter, Manami Sasaki, V. Barbosa Martins, I. Jung-Richardt, G. Heinzelmann, J. Bolmont, G. Emery, S. Schwemmer, Andrea Santangelo, Michael Punch, M. Spir-Jacob, Stefano Gabici, K. Shiningayamwe, J.-P. Ernenwein, Simon Sailer, T. Chand, Jhilik Majumdar, Felix Aharonian, Michael Kreter, M. Böttcher, R. C. G. Chaves, E. O. Angüner, M. Büchele, C. Perennes, André Schulz, Ruizhi Yang, Stefan Ohm, Dieter Horns, C. Levy, Michelle Tsirou, J. Devin, C. Stegmann, Nu. Komin, E. Leser, S. J. Fegan, S. Pita, J.-P. Lenain, A. Carosi, N. Shafi, E. Moulin, G. Henri, P. T. O'Brien, F. Gaté, T. Vuillaume, J. Hahn, Reinhard Schlickeiser, M. Füßling, Dmitry Khangulyan, H. Abdalla, G. Vasileiadis, Werner Hofmann, Gerd Pühlhofer, M. Arakawa, German Hermann, S. Chandra, C. Trichard, M. Holler, A. Reimer, Yves Gallant, Regis Terrier, F. Schüssler, Dmitriy Kostunin, H.M. Schutte, Jonathan Mackey, J. Veh, Quentin Piel, D. A. Sanchez, G. Lamanna, E. de Ona Wilhelmi, R. Rauth, Naomi Tsuji, L. Dirson, Carlo Romoli, Marianne Lemoine-Goumard, M. Barnard, C. Moore, J. Muller, L. Oakes, Marie-Hélène Grondin, R. Zanin, H. Yoneda, Tomasz Bulik, Alison Mitchell, T. Bylund, Zorawar Wadiasingh, S. Klepser, Axel Donath, A. W. Chen, Michal Ostrowski, Andrzej A. Zdziarski, T. Lohse, J. Zorn, Catherine Boisson, Ullrich Schwanke, H. Iwasaki, Andrew M. Taylor, M. Curyło, Armelle Jardin-Blicq, I. D. Davids, Stefan Funk, D. J. van der Walt, Matteo Cerruti, Daniel Huber, Stefan Wagner, Yasunobu Uchiyama, S. Saito, C. van Rensburg, S. Raab, Kirsty Feijen, Shinya Nakashima, Atreyee Sinha, A. Djannati-Ataï, N. Żywucka, R. Steenkamp, H. Sol, P. Brun, Michael Backes, A. Fiasson, Richard J. Tuffs, G. Martí-Devesa, Vincent Marandon, Tim Holch, T. Takahashi, Gianluca Giavitto, R. Blackwell, E. Ruiz-Velasco, P.-O. Petrucci, K. Bernlöhr, Yvonne Becherini, Marek Jamrozy, Gerard Fontaine, B. Khélifi, D. A. Prokhorov, S. Eschbach, Q. Remy, B. Peyaud, B. van Soelen, Andreas Zech, Christo Venter, Włodek Kluźniak, D. Glawion, R. Moderski, J. Hinton, Christoph Deil, Mohanraj Senniappan, Karl Kosack, M.A. Kastendieck, S. Bonnefoy, Mischa Breuhaus, Pol Bordas, Frank M. Rieger, D. Gottschall, C. van Eldik, Mahmoud Mohamed, Felix Jankowsky, Clemens Hoischen, Igor Oya, S. Colafrancesco, J. F. Glicenstein, V. Sahakian, I. Lypova, Łukasz Stawarz, C. Mariaud, Uli Katz, A. Specovius, P. J. Meintjes, Francois Brun, P. Vincent, M. Haupt, Heinrich J. Völk, Jacek Niemiec, A. Lemière, Olaf Reimer, B. Rudak, H. Ndiyavala, Thomas Murach, D. Jankowsky, M. Tluczykont, Andreas Quirrenbach, Kathrin Egberts, S. Caroff, G. Maurin, Ramin Marx, Hirokazu Odaka, A.S. Seyffert, Monica Seglar-Arroyo, F. Niederwanger, Alicja Wierzcholska, Gavin Rowell, Jacco Vink, David Berge, M. Bryan, Sabrina Casanova, R. D. Parsons, A. Priyana Noel, Matthieu Renaud, M. Katsuragawa, L. Giunti, Heike Prokoph, P. deWilt, K. Katarzyński, J. King, T. Tavernier, A. Dmytriiev, C. Arcaro, R. Adam, C. Steppa, Victor Doroshenko, H. Ashkar, M. de Naurois, Alexandre Marcowith, L. Rinchiuso, Rachel Simoni, Arnaud Mares, Johan Bregeon, R. J. White, D. Malyshev, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, H.E.S.S., Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, University of Namibia, Federal Ministry of Education and Research (Germany), Max Planck Society, German Research Foundation, Helmholtz Association, Alexander von Humboldt Foundation, Ministre de l'Enseignement Supérieur, de la Recherche et de l'Innovation (France), Centre National de la Recherche Scientifique (France), Commissariat à l'Ènergie Atomique et aux Ènergies Alternatives (France), Science and Technology Facilities Council (UK), Knut and Alice Wallenberg Foundation, National Science Centre (Poland), Department of Science and Technology (South Africa), National Research Foundation (South Africa), National Commission on Research Science and Technology (Namibia), Federal Ministry of Education, Science and Research (Austria), Japan Society for the Promotion of Science, University of Amsterdam, H.E.S.S. Collaboration, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2)
Subjects: Shock wavesγ-rays: general, VHE [gamma ray], Flux, Astrophysics, 01 natural sciences, 7. Clean energy, Spectral line, star, HESS, flux [gamma ray], Astrophysics::Solar and Stellar Astrophysics, gamma ray: flux, neutron star, 010303 astronomy & astrophysics, orbit, pulsar, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, education.field_of_study, photon, shock waves, modulation, gamma ray: emission, binary [gamma ray], binaries: general, astroparticle physics, slope, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, asymmetry, signature, Astrophysics::High Energy Astrophysical Phenomena, Population, general [Pulsars], FOS: Physical sciences, Orbital eccentricity, Astrophysics::Cosmology and Extragalactic Astrophysics, GLAST, energy dependence, Shock waves, Pulsar, emission [gamma ray], pulsars: general, 0103 physical sciences, general [γ-Rays], education, Astrophysics::Galaxy Astrophysics, non-thermal [Radiation mechanisms], γ-rays: general, general [Binaries], 010308 nuclear & particles physics, gamma ray: binary, Astronomy and Astrophysics, radiation mechanisms: non-thermal, crossing, Light curve, Neutron star, gamma ray: VHE, Space and Planetary Science, HESS - Abteilung Hinton, ddc:520, Astroparticle physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Fermi Gamma-ray Space Telescope
Abstract: [Context] PSR B1259–63/LS 2883 is a gamma-ray binary system consisting of a pulsar in an eccentric orbit around a bright Oe stellar-type companion star that features a dense circumstellar disc. The bright broad-band emission observed at phases close to periastron offers a unique opportunity to study particle acceleration and radiation processes in binary systems. Observations at gamma-ray energies constrain these processes through variability and spectral characterisation studies., [Aims] The high- and very-high-energy (HE, VHE) gamma-ray emission from PSR B1259–63/LS 2883 around the times of its periastron passage are characterised, in particular, at the time of the HE gamma-ray flares reported to have occurred in 2011, 2014, and 2017. Short-term and average emission characteristics of PSR B1259–63/LS 2883 are determined. Super-orbital variability is searched for in order to investigate possible cycle-to-cycle VHE flux changes due to different properties of the companion star’s circumstellar disc and/or the conditions under which the HE gamma-ray flares develop., [Methods] Spectra and light curves were derived from observations conducted with the H.E.S.S-II array in 2014 and 2017. Phase-folded light curves are compared with the results obtained in 2004, 2007, and 2011. Fermi-LAT observations from 2010/11, 2014, and 2017 are analysed., [Results] A local double-peak profile with asymmetric peaks in the VHE light curve is measured, with a flux minimum at the time of periastron tp and two peaks coinciding with the times at which the neutron star crosses the companion’s circumstellar disc (~tp ± 16 d). A high VHE gamma-ray flux is also observed at the times of the HE gamma-ray flares (~tp + 30 d) and at phases before the first disc crossing (~tp − 35 d). The spectral energy range now extends to below 200 GeV and up to ~45 TeV., [Conclusions] PSR B1259–63/LS 2883 displays periodic flux variability at VHE gamma-rays without clear signatures of super-orbital modulation in the time span covered by the monitoring of the source with the H.E.S.S. telescopes. This flux variability is most probably caused by the changing environmental conditions, particularly at times close to periastron passage at which the neutron star is thought to cross the circumstellar disc of the companion star twice. In contrast, the photon index remains unchanged within uncertainties for about 200 d around periastron. At HE gamma-rays, PSR B1259–63/LS 2883 has now been detected also before and after periastron, close to the disc crossing times. Repetitive flares with distinct variability patterns are detected in this energy range. Such outbursts are not observed at VHEs, although a relatively high emission level is measured. The spectra obtained in both energy regimes displays a similar slope, although a common physical origin either in terms of a related particle population, emission mechanism, or emitter location is ruled out., The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat a l’Énergie atomique et aux Énergies alternatives (CEA), the U.K. Science and Technology Facilities Council (STFC), the Knut and Alice Wallenberg Foundation, the National Science Centre, Poland grant no. 2016/22/M/ST9/00382, the South African Department of Science and Technology and National Research Foundation, the University of Namibia, the National Commission on Research, Science & Technology of Namibia (NCRST), the Austrian Federal Ministry of Education, Science and Research and the Austrian Science Fund (FWF), the Australian Research Council (ARC), the Japan Society for the Promotion of Science and by the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Zeuthen, Heidelberg, Palaiseau, Paris, Saclay, Tübingen and in Namibia in the construction and operation of the equipment. This work benefitted from services provided by the H.E.S.S. Virtual Organisation, supported by the national resource providers of the EGI Federation.
Published: 2020
Full Text: View/download PDF

49. Resolving the Crab pulsar wind nebula at teraelectronvolt energies

Author: Natalia Żywucka, M. de Naurois, T. Chand, Frank M. Rieger, J. Bolmont, S. Colafrancesco, Ruizhi Yang, W. Kluźniak, S. Eschbach, Jim Hinton, R. Simoni, Dmitry Khangulyan, Christopher J. Moore, G. Fontaine, M. Büchele, D. A. Sanchez, T. Tavernier, L. Mohrmann, Denys Malyshev, J. Veh, S. Klepser, B. Khélifi, H. M. Schutte, C. Perennes, D. Glawion, Christoph Deil, Mohanraj Senniappan, A.A. Zdziarski, A. Djannati-Ataï, Y.A. Gallant, Gavin Rowell, Stefan Funk, T. Takahashi, Gianluca Giavitto, Axel Donath, A. W. Chen, M. Bryan, J. Dyks, D. Zaborov, I. Oya, G. Heinzelmann, K. Shiningayamwe, T. Lohse, Yvonne Becherini, M. Renaud, H. Iwasaki, M. Holler, J.-P. Ernenwein, P. Vincent, R. D. Parsons, G. Emery, H. Odaka, Christo Venter, D. Huber, M. Arakawa, D. Berge, M. Capasso, Matteo Cerruti, Nachiketa Chakraborty, F. Niederwanger, A. Marcowith, A. Zech, E. Leser, Jacco Vink, R. Rauth, Sabrina Casanova, C. Arcaro, I. Jung-Richardt, T. Vuillaume, G. Hermann, D. Gottschall, Werner Hofmann, Regis Terrier, J. Becker Tjus, A. Schulz, Carlo Romoli, M. Panter, M. Seglar-Arroyo, H. Ndiyavala, B. van Soelen, Felix Aharonian, M. Haupt, Lukasz Stawarz, Michael Punch, V. Doroshenko, M. Spir-Jacob, R. Tuffs, R. C. G. Chaves, E. O. Angüner, A. Priyana Noel, L. O'c. Drury, S. Saito, J.F. Glicenstein, D. J. van der Walt, S. Raab, Andreas Quirrenbach, C. Steppa, J.-P. Lenain, N. Shafi, K. Egberts, Robert Wagner, K. Kosack, J. Hahn, Reinhard Schlickeiser, M. Tsirou, G. Vasileiadis, M. Kraus, S. Chandra, S. Nakashima, G. Martí-Devesa, M. Katsuragawa, Ruben Lopez-Coto, M.-H. Grondin, M. Böttcher, R. Blackwell, E. Ruiz-Velasco, L. Dirson, Stefan Ohm, Léa Jouvin, S. Pita, F. Schüssler, P. deWilt, J. King, F. Voisin, Julien Lefaucheur, A. Dmytriiev, R. Moderski, S. Gabici, A. Fiasson, J. Lau, L. Oakes, I.D. Davids, Alison Mitchell, L. Rinchiuso, P.J. Meintjes, Heike Prokoph, Zorawar Wadiasingh, R. J. White, S. Fegan, Dieter Horns, V. Poireau, Monica Barnard, P.-O. Petrucci, H. Abdalla, D. Jankowsky, Q. Piel, C. Stegmann, Nu. Komin, Marek Jamrozy, Catherine Boisson, Helene Sol, Pierre Brun, A.S. Seyffert, A. Carosi, M. Füßling, M.A. Kastendieck, S. Bonnefoy, N. Tsuji, F. Gaté, J. Devin, G. Henri, D. A. Prokhorov, D. Tiziani, C. Hoischen, Ullrich Schwanke, A. Specovius, R. Steenkamp, A. Reimer, J. Bregeon, Francois Brun, B. Condon, Michael Backes, H. Yoneda, Tim Holch, M. Tluczykont, E. Moulin, Tomasz Bulik, T. Bylund, A. Jacholkowska, S. Caroff, Celine Armand, F. Jankowsky, Stefan Wagner, Yasunobu Uchiyama, C. van Rensburg, M. Zacharias, C. Trichard, F. Ait Benkhali, Manami Sasaki, S. Schwemmer, Andrea Santangelo, A. Ziegler, G. Maurin, A. Wierzcholska, C. Mariaud, Jacek Niemiec, Olaf Reimer, Thomas Murach, A. Lemière, M. Lemoine-Goumard, I. Shilon, Heinrich J. Völk, R. Marx, P. Bordas, I. Lypova, G. Lamanna, J. Zorn, U. Katz, J.-P. Tavernet, B. Rudak, V. Marandon, K. Katarzyński, A.M. Taylor, V. Sahakian, M. Mohamed, M. Ostrowski, Konrad Bernlöhr, B. Peyaud, G. Pühlhofer, R. Zanin, P. T. O'Brien, Atreyee Sinha, C. van Eldik, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, H.E.S.S., Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), European Commission, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Armagh Observatory, Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), Gravitation and Astroparticle Physics Amsterdam, 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 26403366 - Ndiyavala, Hambeleleni, 10060499 - Van der Walt, Diederick Johannes, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 29092086 - Zacharias, Michael, and Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Electromagnetic spectrum, electron: relativistic, magnetic field, Astrophysics, positron: energy, 01 natural sciences, 7. Clean energy, Pulsar wind nebula, particle: acceleration, Raigs gamma, Astrophysics::Solar and Stellar Astrophysics, HESS - Abteilung Hofmann, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, pulsar, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, [PHYS]Physics [physics], Nebula, radio wave, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 4. Education, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], photon, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, High-energy astrophysics, Particle astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Camps magnètics, accelerator, High-energy astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, gap, X-ray, energy loss: rotation, Pulsar, 0103 physical sciences, synchrotron, Astrophysics::Galaxy Astrophysics, gamma ray: energy, 0105 earth and related environmental sciences, Crab Pulsar, Gamma rays, Astronomy and Astrophysics, Crab Nebula, electromagnetic, gamma ray: VHE, [SDU]Sciences of the Universe [physics], Magnetic fields, ddc:520, Physics::Accelerator Physics
Abstract: arXiv:1909.09494v2, H.E.S.S. Collaboration: et al., The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat à l’énergie atomique et aux énergies alternatives (CEA), the UK Science and Technology Facilities Council (STFC), the Knut and Alice Wallenberg Foundation, the National Science Centre, Poland (grant number 2016/22/M/ST9/00382), the South African Department of Science and Technology and the National Research Foundation, the University of Namibia, the National Commission on Research, Science and Technology of Namibia (NCRST), the Austrian Federal Ministry of Education, Science and Research and the Austrian Science Fund (FWF), the Australian Research Council (ARC), the Japan Society for the Promotion of Science and the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Zeuthen, Heidelberg, Palaiseau, Paris, Saclay, Tübingen and Namibia in the construction and operation of the equipment. This work benefited from services provided by the H.E.S.S. Virtual Organisation, supported by the national resource providers of the EGI Federation. R.C.G.C. was funded by EU FP7 Marie Curie (grant agreement number PIEF-GA-2012-332350).
Published: 2020
Full Text: View/download PDF

50. Search for dark matter signals towards a selection of recently detected DES dwarf galaxy satellites of the Milky Way with HESS

Author: Collaboration, H. E. S. S., Abdallah, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Breuhaus, M., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dyks, J., Egberts, K., Eichhorn, F., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martì-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Parsons, R. D., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutter, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S., Zorn, J., Żywucka, N., 26598973 - Abdalla, Hassan, 30588766 - Arcaro, Cornelia, 28644743 - Backes, Michael, 20574266 - Barnard, Monica, 24420530 - Böttcher, Markus, 30366755 - Chand, Tej B., 31125417 - Chandra, Sunil, 33379009 - Kreter, Michael, 26403366 - Ndiyavala, Hambeleleni, 22799133 - Schutte, Hester M., 20126999 - Seyffert, Albertus Stefanus, 10060499 - Van der Walt, Diederick Johannes, 21106266 - Van Rensburg, Carlo, 12006653 - Venter, Christo, 26594080 - Wadiasingh, Zorawar, 29092086 - Zacharias, Michael, 34208968 - Zywucka-Hejzner, Natalia, Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), H.E.S.S., Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), H. E. S. S. Collaboration, Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Faculty of Science, High Energy Astrophys. & Astropart. Phys (API, FNWI), and API Other Research (FNWI)
Subjects: atmosphere [Cherenkov counter], VHE [gamma ray], mass [dark matter], Astrophysics, 01 natural sciences, 7. Clean energy, galaxy: halo, S046PHB, HESS, Gamma ray astronomy, dark energy, Physics, density, OBSERVATÓRIOS, imaging, halo [dark matter], halo [galaxy], gamma ray: emission, Weakly interacting massive particles, VERITAS, Astrophysics - High Energy Astrophysical Phenomena, Particle astrophysics, Cosmology & astrophysics, Gravitation, WIMP, Milky Way, Astrophysics::High Energy Astrophysical Phenomena, satellite, Dark matter, Astrophysics::Cosmology and Extragalactic Astrophysics, Cherenkov counter: atmosphere, GLAST, cross section: annihilation, S030DMA, Galactic halo, statistical analysis, dark matter: halo, cosmic rays, emission [gamma ray], 0103 physical sciences, Experiments in gravity, ddc:530, 14. Life underwater, 010306 general physics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, background, 010308 nuclear & particles physics, dark matter: mass, sensitivity, MAGIC, Galaxy, Dwarf spheroidal galaxy, Dark matter halo, annihilation [cross section], gamma ray: VHE, 13. Climate action, HESS - Abteilung Hinton, Higgsino, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], HAWC, cosmology, Telescopes
Abstract: Dwarf spheroidal galaxy satellites of the Milky Way are prime targets for indirect detection of dark matter with gamma rays due to their proximity, high dark matter content and absence of non-thermal emission processes. Recently, the Dark Energy Survey (DES) revealed the existence of new ultra-faint dwarf spheroidal galaxies in the southern-hemisphere sky, therefore ideally located for ground-based observations with the imaging atmospheric Cherenkov telescope array H.E.S.S. We present a search for very-high-energy ($E\gtrsim100$ GeV) gamma-ray emission using H.E.S.S. observations carried out recently towards Reticulum II, Tucana II, Tucana III, Tucana IV and Grus II satellites. No significant very-high-energy gamma-ray excess is found from the observations on any individual object nor in the combined analysis of all the datasets. Using the most recent modeling of the dark matter distribution in the dwarf galaxy halo, we compute for the first time on DES satellites individual and combined constraints from Cherenkov telescope observations on the annihilation cross section of dark matter particles in the form of Weakly Interacting Massive Particles. The combined 95% C.L. observed upper limits reach $\langle \sigma v \rangle \simeq 1 \times 10^{-23}$ cm$^3$s$^{-1}$ in the $W^+W^-$ channel and $4 \times 10^{-26}$ cm$^3$s$^{-1}$ in the $\gamma\gamma$ channels for a dark matter mass of 1.5 TeV. The H.E.S.S. constraints well complement the results from Fermi-LAT, HAWC, MAGIC and VERITAS and are currently the most stringent in the $\gamma\gamma$ channels in the multi-GeV/multi-TeV mass range., Comment: 20 pages, 12 figures
Published: 2020
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

88 results on '"Barnard, Monica"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources