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1. Constraints on the Intergalactic Magnetic Field Using Fermi-LAT and H.E.S.S. Blazar Observations

Author

F. Aharonian, J. Aschersleben, M. Backes, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, B. Bi, M. Bouyahiaoui, M. Breuhaus, R. Brose, F. Brun, B. Bruno, T. Bulik, C. Burger-Scheidlin, T. Bylund, S. Caroff, S. Casanova, J. Celic, M. Cerruti, T. Chand, S. Chandra, A. Chen, J. Chibueze, O. Chibueze, G. Cotter, M. de Bony, K. Egberts, J.-P. Ernenwein, G. Fichet de Clairfontaine, M. Filipovic, G. Fontaine, M. Füssling, S. Funk, S. Gabici, S. Ghafourizadeh, G. Giavitto, D. Glawion, J. F. Glicenstein, P. Goswami, M.-H. Grondin, L. Haerer, T. L. Holch, M. Holler, D. Horns, M. Jamrozy, F. Jankowsky, V. Joshi, I. Jung-Richardt, E. Kasai, K. Katarzyński, R. Khatoon, B. Khélifi, W. Kluźniak, Nu. Komin, K. Kosack, D. Kostunin, R. G. Lang, S. Le Stum, F. Leitl, A. Lemière, J.-P. Lenain, F. Leuschner, T. Lohse, A. Luashvili, I. Lypova, J. Mackey, D. Malyshev, V. Marandon, P. Marchegiani, A. Marcowith, G. Martí-Devesa, R. Marx, M. Meyer, A. Mitchell, R. Moderski, L. Mohrmann, A. Montanari, E. Moulin, J. Muller, T. Murach, K. Nakashima, J. Niemiec, S. Ohm, L. Olivera-Nieto, E. de Ona Wilhelmi, S. Panny, M. Panter, R. D. Parsons, G. Peron, D. A. Prokhorov, H. Prokoph, G. Pühlhofer, M. Punch, A. Quirrenbach, P. Reichherzer, A. Reimer, O. Reimer, B. Reville, F. Rieger, G. Rowell, B. Rudak, E. Ruiz-Velasco, V. Sahakian, D. A. Sanchez, M. Sasaki, F. Schüssler, H. M. Schutte, U. Schwanke, J. N. S. Shapopi, H. Sol, S. Spencer, S. Steinmassl, H. Suzuki, T. Takahashi, T. Tanaka, A. M. Taylor, R. Terrier, C. Thorpe-Morgan, M. Tsirou, N. Tsuji, Y. Uchiyama, C. van Eldik, J. Veh, C. Venter, S. J. Wagner, R. White, A. Wierzcholska, Yu Wun Wong, M. Zacharias, D. Zargaryan, A. A. Zdziarski, S. Zouari, N. Żywucka, H.E.S.S. Collaboration, and Fermi-LAT Collaboration

Subjects
Active galaxies, High energy astrophysics, Extragalactic magnetic fields, Astrophysics, QB460-466
Abstract

Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) the IGMF can be obtained from observations of high-energy gamma rays from distant blazars. Gamma rays interact with the extragalactic background light to produce electron−positron pairs, which can subsequently initiate electromagnetic cascades. The gamma-ray signature of the cascade depends on the IGMF since it deflects the pairs. Here we report on a new search for this cascade emission using a combined data set from the Fermi Large Area Telescope and the High Energy Stereoscopic System. Using state-of-the-art Monte Carlo predictions for the cascade signal, our results place a lower limit on the IGMF of B > 7.1 × 10 ^−16 G for a coherence length of 1 Mpc even when blazar duty cycles as short as 10 yr are assumed. This improves on previous lower limits by a factor of 2. For longer duty cycles of 10 ^4 (10 ^7 ) yr, IGMF strengths below 1.8 × 10 ^−14 G (3.9 × 10 ^−14 G) are excluded, which rules out specific models for IGMF generation in the early universe.

Published
2023
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2. A MeerKAT, e-MERLIN, HESS, and Swift search for persistent and transient emission associated with three localized FRBs

Author

J O Chibueze, M Caleb, L Spitler, H Ashkar, F Schüssler, B W Stappers, C Venter, I Heywood, A M S Richards, D R A Williams, M Kramer, R Beswick, M C Bezuidenhout, R P Breton, L N Driessen, F Jankowski, E F Keane, M Malenta, M Mickaliger, V Morello, H Qiu, K Rajwade, S Sanidas, M Surnis, T W Scragg, C R H Walker, N Wrigley, H E S S Collaboration: F Aharonian, F Ait Benkhali, E O Angüner, M Backes, V Baghmanyan, V Barbosa Martins, R Batzofin, Y Becherini, D Berge, M Böttcher, C Boisson, J Bolmont, M de Bony de Lavergne, M Breuhaus, R Brose, F Brun, T Bulik, F Cangemi, S Caroff, S Casanova, J Catalano, M Cerruti, T Chand, A Chen, O U Chibueze, G Cotter, P Cristofari, J Damascene Mbarubucyeye, J Devin, A Djannati-Ataï, A Dmytriiev, K Egberts, J-P Ernenwein, A Fiasson, G Fichet de Clairfontaine, G Fontaine, S Funk, S Gabici, S Ghafourizadeh, G Giavitto, D Glawion, M-H Grondin, M Hörbe, C Hoischen, T L Holch, Zhiqiu Huang, M Jamrozy, F Jankowsky, V Joshi, I Jung-Richardt, E Kasai, K Katarzyński, U Katz, B Khélifi, W Kluźniak, Nu Komin, K Kosack, D Kostunin, A Lemière, J-P Lenain, F Leuschner, T Lohse, A Luashvili, I Lypova, J Mackey, D Malyshev, V Marandon, P Marchegiani, A Marcowith, G Martí-Devesa, R Marx, A Mitchell, R Moderski, L Mohrmann, E Moulin, J Muller, K Nakashima, M de Naurois, A Nayerhoda, J Niemiec, A Priyana Noel, P O’Brien, S Ohm, L Olivera-Nieto, E de Ona Wilhelmi, M Ostrowski, S Panny, R D Parsons, S Pita, V Poireau, D A Prokhorov, H Prokoph, G Pühlhofer, A Quirrenbach, P Reichherzer, A Reimer, O Reimer, G Rowell, B Rudak, E Ruiz-Velasco, V Sahakian, S Sailer, H Salzmann, D A Sanchez, A Santangelo, M Sasaki, H M Schutte, U Schwanke, J N S Shapopi, A Specovius, S Spencer, R Steenkamp, S Steinmassl, T Takahashi, T Tanaka, C Thorpe-Morgan, N Tsuji, C van Eldik, J Veh, J Vink, S J Wagner, A Wierzcholska, Yu Wun Wong, A Yusafzai, M Zacharias, D Zargaryan, A A Zdziarski, A Zech, S J Zhu, S Zouari, N Żywucka, High Energy Astrophys. & Astropart. Phys (API, FNWI), 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), 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 Paris Cité (UPCité), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, 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 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), Université de Bordeaux (UB), Laboratoire Univers et Particules de Montpellier (LUPM), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)

Subjects
radio continuum: galaxies, High Energy Astrophysical Phenomena (astro-ph.HE), ) fast radio burst [(transients], FOS: Physical sciences, Astronomy and Astrophysics, radiation mechanisms: non-thermal, non-thermal [radiation mechanisms], Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], fast radio bursts, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), (transients:) fast radio burst, ddc:520, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Monthly notices of the Royal Astronomical Society 515(1), 1365 - 1379 (2022). doi:10.1093/mnras/stac1601, We report on a search for persistent radio emission from the one-off fast radio burst (FRB) 20190714A, as well as from two repeating FRBs, 20190711A and 20171019A, using the MeerKAT radio telescope. For FRB 20171019A, we also conducted simultaneous observations with the High-Energy Stereoscopic System (H.E.S.S.) in very high-energy gamma rays and searched for signals in the ultraviolet, optical, and X-ray bands. For this FRB, we obtain a UV flux upper limit of |$1.39 \times 10^{-16}~{\rm erg\, cm^{-2}\, s^{-1}}$|Å^−1, X-ray limit of |$\sim 6.6 \times 10^{-14}~{\rm erg\, cm^{-2}\, s^{-1}}$| and a limit on the very high energy gamma-ray flux |$\Phi (E\gt 120\, {\rm GeV}) \lt 1.7\times 10^{-12}\, \mathrm{erg\, cm^{-2}\, s^{-1}}$|⁠. We obtain a radio upper limit of ∼15 |$\mu$|Jy beam^−1 for persistent emission at the locations of both FRBs 20190711A and 20171019A with MeerKAT. However, we detected an almost unresolved (ratio of integrated flux to peak flux is ∼1.7 beam) radio emission, where the synthesized beam size was ∼ 8 arcsec size with a peak brightness of |$\sim 53\, \mu$|Jy beam^−1 at MeerKAT and |$\sim 86\, \mu$|Jy beam^−1 at e-MERLIN, possibly associated with FRB 20190714A at z = 0.2365. This represents the first detection of persistent continuum radio emission potentially associated with a (as-yet) non-repeating FRB. If the association is confirmed, one of the strongest remaining distinction between repeaters and non-repeaters would no longer be applicable. A parallel search for repeat bursts from these FRBs revealed no new detections down to a fluence of 0.08 Jy ms for a 1 ms duration burst., Published by Oxford Univ. Press, Oxford

Published
2023
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3. Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey.

Author

Abdalla H, Aharonian F, Benkhali FA, Angüner EO, Armand C, Ashkar H, Backes M, Baghmanyan V, Martins VB, Batzofin R, Becherini Y, Berge D, Bernlöhr K, Bi B, Böttcher M, Bolmont J, de Lavergne MB, Brose R, Brun F, Cangemi F, Caroff S, Cerruti M, Chand T, Chen A, Cotter G, Mbarubucyeye JD, Devin J, Djannati-Ataï A, Dmytriiev A, Doroshenko V, Egberts K, Fiasson A, de Clairfontaine GF, Fontaine G, Funk S, Gabici S, Giavitto G, Glawion D, Glicenstein JF, Grondin MH, Hinton JA, Hofmann W, Holch TL, Holler M, Horns D, Huang Z, Jamrozy M, Jankowsky F, Kasai E, Katarzyński K, Katz U, Khélifi B, Kluźniak W, Komin N, Kosack K, Kostunin D, Lamanna G, Lemoine-Goumard M, Lenain JP, Leuschner F, Lohse T, Luashvili A, Lypova I, Mackey J, Malyshev D, Malyshev D, Marandon V, Marchegiani P, Martí-Devesa G, Marx R, Maurin G, Meyer M, Mitchell A, Moderski R, Montanari A, Moulin E, Muller J, de Naurois M, Niemiec J, Noel AP, Ohm S, Olivera-Nieto L, Wilhelmi EO, Ostrowski M, Panny S, Panter M, Parsons RD, Peron G, Poireau V, Prokoph H, Pühlhofer G, Punch M, Quirrenbach A, Reichherzer P, Reimer A, Reimer O, Renaud M, Rieger F, Rowell G, Rudak B, Ricarte HR, Ruiz-Velasco E, Sahakian V, Salzmann H, Santangelo A, Sasaki M, Schüssler F, Schutte HM, Schwanke U, Senniappan M, Shapopi JNS, Sol H, Specovius A, Spencer S, Stawarz Ł, Stegmann C, Steinmassl S, Steppa C, Takahashi T, Tanaka T, Terrier R, Thorpe-Morgan C, Tluczykont M, Tsirou M, Tsuji N, Uchiyama Y, van Eldik C, Veh J, Vink J, Wagner SJ, White R, Wierzcholska A, Wong YW, Zacharias M, Zargaryan D, Zdziarski AA, Zech A, Zhu SJ, Zouari S, and Żywucka N

Abstract

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100  GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26}  cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26}  cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Published
2022
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4. Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi.

Author

Aharonian F, Ait Benkhali F, Angüner EO, Ashkar H, Backes M, Baghmanyan V, Barbosa Martins V, Batzofin R, Becherini Y, Berge D, Bernlöhr K, Bi B, Böttcher M, Boisson C, Bolmont J, de Bony de Lavergne M, Breuhaus M, Brose R, Brun F, Caroff S, Casanova S, Cerruti M, Chand T, Chen A, Cotter G, Damascene Mbarubucyeye J, Djannati-Ataï A, Dmytriiev A, Doroshenko V, Duffy C, Egberts K, Ernenwein JP, Fegan S, Feijen K, Fiasson A, Fichet de Clairfontaine G, Fontaine G, Füßling M, Funk S, Gabici S, Gallant YA, Ghafourizadeh S, Giavitto G, Giunti L, Glawion D, Glicenstein JF, Grondin MH, Hermann G, Hinton JA, Hörbe M, Hofmann W, Hoischen C, Holch TL, Holler M, Horns D, Huang Z, Jamrozy M, Jankowsky F, Jung-Richardt I, Kasai E, Katarzyński K, Katz U, Khangulyan D, Khélifi B, Klepser S, Kluźniak W, Komin N, Konno R, Kosack K, Kostunin D, Le Stum S, Lemière A, Lemoine-Goumard M, Lenain JP, Leuschner F, Lohse T, Luashvili A, Lypova I, Mackey J, Malyshev D, Malyshev D, Marandon V, Marchegiani P, Marcowith A, Martí-Devesa G, Marx R, Maurin G, Meyer M, Mitchell A, Moderski R, Mohrmann L, Montanari A, Moulin E, Muller J, Murach T, Nakashima K, de Naurois M, Nayerhoda A, Niemiec J, Priyana Noel A, O'Brien P, Ohm S, Olivera-Nieto L, de Ona Wilhelmi E, Ostrowski M, Panny S, Panter M, Parsons RD, Peron G, Pita S, Poireau V, Prokhorov DA, Prokoph H, Pühlhofer G, Punch M, Quirrenbach A, Reichherzer P, Reimer A, Reimer O, Renaud M, Reville B, Rieger F, Rowell G, Rudak B, Rueda Ricarte H, Ruiz-Velasco E, Sahakian V, Sailer S, Salzmann H, Sanchez DA, Santangelo A, Sasaki M, Schäfer J, Schüssler F, Schutte HM, Schwanke U, Senniappan M, Shapopi JNS, Simoni R, Sinha A, Sol H, Specovius A, Spencer S, Stawarz Ł, Steinmassl S, Steppa C, Takahashi T, Tanaka T, Taylor AM, Terrier R, Thorpe-Morgan C, Tsirou M, Tsuji N, Tuffs R, Uchiyama Y, Unbehaun T, van Eldik C, van Soelen B, Veh J, Venter C, Vink J, Wagner SJ, Werner F, White R, Wierzcholska A, Wong YW, Yusafzai A, Zacharias M, Zargaryan D, Zdziarski AA, Zech A, Zhu SJ, Zouari S, and Żywucka N

Abstract

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE; [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to 1 month after its 2021 outburst, observed using the High Energy Stereoscopic System (H.E.S.S.). The temporal profile of VHE emission is similar to that of lower-energy giga-electron volt emission, indicating a common origin, with a 2-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic rays to very high energies.

Published
2022
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