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1. Toward the end-to-end optimization of particle physics instruments with differentiable programming

Author: Tommaso Dorigo, Andrea Giammanco, Pietro Vischia, Max Aehle, Mateusz Bawaj, Alexey Boldyrev, Pablo de Castro Manzano, Denis Derkach, Julien Donini, Auralee Edelen, Federica Fanzago, Nicolas R. Gauger, Christian Glaser, Atılım G. Baydin, Lukas Heinrich, Ralf Keidel, Jan Kieseler, Claudius Krause, Maxime Lagrange, Max Lamparth, Lukas Layer, Gernot Maier, Federico Nardi, Helge E.S. Pettersen, Alberto Ramos, Fedor Ratnikov, Dieter Röhrich, Roberto Ruiz de Austri, Pablo Martínez Ruiz del Árbol, Oleg Savchenko, Nathan Simpson, Giles C. Strong, Angela Taliercio, Mia Tosi, Andrey Ustyuzhanin, and Haitham Zaraket
Subjects: Particle detectors, Differentiable programming, Machine learning, Optimization, Particle physics, Nuclear physics, Physics, QC1-999
Abstract: The full optimization of the design and operation of instruments whose functioning relies on the interaction of radiation with matter is a super-human task, due to the large dimensionality of the space of possible choices for geometry, detection technology, materials, data-acquisition, and information-extraction techniques, and the interdependence of the related parameters. On the other hand, massive potential gains in performance over standard, “experience-driven” layouts are in principle within our reach if an objective function fully aligned with the final goals of the instrument is maximized through a systematic search of the configuration space. The stochastic nature of the involved quantum processes make the modeling of these systems an intractable problem from a classical statistics point of view, yet the construction of a fully differentiable pipeline and the use of deep learning techniques may allow the simultaneous optimization of all design parameters.In this white paper, we lay down our plans for the design of a modular and versatile modeling tool for the end-to-end optimization of complex instruments for particle physics experiments as well as industrial and medical applications that share the detection of radiation as their basic ingredient. We consider a selected set of use cases to highlight the specific needs of different applications.
Published: 2023
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2. Toward the end-to-end optimization of particle physics instruments with differentiable programming

Author: Tommaso Dorigo, Andrea Giammanco, Pietro Vischia, Max Aehle, Mateusz Bawaj, Alexey Boldyrev, Pablo de Castro Manzano, Denis Derkach, Julien Donini, Auralee Edelen, Federica Fanzago, Nicolas R. Gauger, Christian Glaser, Atılım G. Baydin, Lukas Heinrich, Ralf Keidel, Jan Kieseler, Claudius Krause, Maxime Lagrange, Max Lamparth, Lukas Layer, Gernot Maier, Federico Nardi, Helge E.S. Pettersen, Alberto Ramos, Fedor Ratnikov, Dieter Röhrich, Roberto Ruiz de Austri, Pablo Martínez Ruiz del Árbol, Oleg Savchenko, Nathan Simpson, Giles C. Strong, Angela Taliercio, Mia Tosi, Andrey Ustyuzhanin, and Haitham Zaraket
Subjects: Optimization, Machine learning, Nuclear physics, Particle physics, General Physics and Astronomy, Particle detectors, Differentiable programming, Detectors and Experimental Techniques, Astrophysics, physics.ins-det
Abstract: The full optimization of the design and operation of instruments whose functioning relies on the interaction of radiation with matter is a super-human task, due to the large dimensionality of the space of possible choices for geometry, detection technology, materials, data-acquisition, and information-extraction techniques, and the interdependence of the related parameters. On the other hand, massive potential gains in performance over standard, “experience-driven” layouts are in principle within our reach if an objective function fully aligned with the final goals of the instrument is maximized through a systematic search of the configuration space. The stochastic nature of the involved quantum processes make the modeling of these systems an intractable problem from a classical statistics point of view, yet the construction of a fully differentiable pipeline and the use of deep learning techniques may allow the simultaneous optimization of all design parameters. In this white paper, we lay down our plans for the design of a modular and versatile modeling tool for the end-to-end optimization of complex instruments for particle physics experiments as well as industrial and medical applications that share the detection of radiation as their basic ingredient. We consider a selected set of use cases to highlight the specific needs of different applications. The full optimization of the design and operation of instruments whose functioning relies on the interaction of radiation with matter is a super-human task, given the large dimensionality of the space of possible choices for geometry, detection technology, materials, data-acquisition, and information-extraction techniques, and the interdependence of the related parameters. On the other hand, massive potential gains in performance over standard, "experience-driven" layouts are in principle within our reach if an objective function fully aligned with the final goals of the instrument is maximized by means of a systematic search of the configuration space. The stochastic nature of the involved quantum processes make the modeling of these systems an intractable problem from a classical statistics point of view, yet the construction of a fully differentiable pipeline and the use of deep learning techniques may allow the simultaneous optimization of all design parameters. In this document we lay down our plans for the design of a modular and versatile modeling tool for the end-to-end optimization of complex instruments for particle physics experiments as well as industrial and medical applications that share the detection of radiation as their basic ingredient. We consider a selected set of use cases to highlight the specific needs of different applications.
Published: 2022

3. Untersuchung des Thermal Runaway in Lithium-Ionen-Batteriesystemen

Author: Gernot Maier, Lucas Eder, Jürgen Schneider, and Daniele Suzzi
Subjects: Materials science, Metallurgy, General Medicine
Published: 2020

4. Lösungen für die Schnittstelle Mensch/Maschine

Author: Gernot Maier and Willibald Rabenhaupt
Published: 2022

5. Survey of Open Data Concepts Within Fundamental Physics: An Initiative of the PUNCH4NFDI Consortium

Author: Harry Enke, Andreas Haungs, Thomas Schörner-Sadenius, Kilian Schwarz, Markus Demleitner, Achim Geiser, Lukas Heinrich, Michael Kramer, Gernot Maier, Dominik Schwarz, Hendrik Seitz-Moskaliuk, Hubert Simma, Michael Sterzik, and Stefan Typel
Subjects: Nuclear and High Energy Physics, TheoryofComputation_COMPUTATIONBYABSTRACTDEVICES, Computer Science (miscellaneous), Fundamental science · Physics · FAIR data · Open data · Open science, ddc:004, Software, Computing and Computers
Abstract: Computing and software for big science 6(1), 6 (2022). doi:10.1007/s41781-022-00081-7, PUNCH4NFDI (Particles, Universe, NuClei and Hadrons for the NFDI) aims at developing concepts and tools for the efficient management of digital research products in fundamental physics research. At the heart of the research products are scientific data sets that should be made interoperable and available to a broad scientific community and the public for a sustainable usage (��open data��). The first PUNCH4NFDI ��Open Data Workshop�� gave the opportunity for an initial survey of existing and planned open data initiatives within the PUNCH science field. The paper addresses the conceptual differences and commonalities presented in the workshop. Existing open datasets were presented and discussed. This is an inquiry into the community��s requirements for a better use of open data and in this context also of ��OpenScience��., Published by Springer International Publishing, Cham, Switzerland
Published: 2022

6. Identifying muon rings in VERITAS data using convolutional neural networks trained on images classified with Muon Hunters 2

Author: Matthew Lundy, A. Brill, M. Capasso, Hugh Dickinson, Manel Errando, T. J. Williamson, S. Kumar, S. Patel, Vladimir Vassiliev, M. J. Lang, David Hanna, P. Moriarty, John L. Quinn, Orel Gueta, donggeun tak, David A. Williams, Michael Laraia, Sameer Patel, Jodi Christiansen, P. Wilcox, Thomas Brian Humensky, C. E. McGrath, Alasdair E. Gent, R.R. Prado, Avery Archer, K. Ragan, M. Kertzman, C. Adams, M. Nievas-Rosillo, J. H. Buckley, Reshmi Mukherjee, David Kieda, Tobias Kleiner, A. J. Chromey, A. D. Falcone, Philip Kaaret, James M. Ryan, Wystan Benbow, Lucy Fortson, A. N. Otte, R. A. Ong, C. Giuri, K. A. Farrell, G. M. Foote, Deivid Ribeiro, Stephen Serjeant, E. Roache, Martin Pohl, Binita Hona, Jamie Holder, G. H. Sembroski, Daniel Nieto, K. Pfrang, S. O'Brien, Kevin Flanagan, Amanda Weinstein, Gary Gillanders, Marcos Santander, Q. Feng, I. Sadeh, Darryl Wright, R. Shang, W. Jin, Olivier Hervet, Gernot Maier, P. T. Reynolds, Amy Furniss, and E. Pueschel
Subjects: Muon, Physics::Instrumentation and Detectors, Calibration (statistics), Computer science, business.industry, Pattern recognition, Convolutional neural network, law.invention, Image (mathematics), Hough transform, Telescope, Identification (information), law, Computer Science::Computer Vision and Pattern Recognition, False positive paradox, High Energy Physics::Experiment, Artificial intelligence, business
Abstract: Muons from extensive air showers appear as rings in images taken with imaging atmospheric Cherenkov telescopes, such as VERITAS. These muon-ring images are used for the calibration of the VERITAS telescopes, however the calibration accuracy can be improved with a more efficient muon-identification algorithm. Convolutional neural networks (CNNs) are used in many state-of-the-art image-recognition systems and are ideal for muon image identification, once trained on a suitable dataset with labels for muon images. However, by training a CNN on a dataset labelled by existing algorithms, the performance of the CNN would be limited by the suboptimal muon-identification efficiency of the original algorithms. Muon Hunters 2 is a citizen science project that asks users to label grids of VERITAS telescope images, stating which images contain muon rings. Each image is labelled 10 times by independent volunteers, and the votes are aggregated and used to assign a `muon' or `non-muon' label to the corresponding image. An analysis was performed using an expert-labelled dataset in order to determine the optimal vote percentage cut-offs for assigning labels to each image for CNN training. This was optimised so as to identify as many muon images as possible while avoiding false positives. The performance of this model greatly improves on existing muon identification algorithms, identifying approximately 30 times the number of muon images identified by the current algorithm implemented in VEGAS (VERITAS Gamma-ray Analysis Suite), and roughly 2.5 times the number identified by the Hough transform method, along with significantly outperforming a CNN trained on VEGAS-labelled data.
Published: 2021

7. TeV and optical observations of the Be/pulsar binary 1A0535+262 during the 2020 giant outburst

Author: Matthew Lundy, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Weidong Jin, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, Binary number, FOS: Physical sciences, Cosmic ray, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Binary pulsar, law.invention, Pulsar, law, Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation, Flare
Abstract: 1A 0535+262 is a Be X-ray binary pulsar and one of the only galactic pulsar systems to show radio jet emission. Characterizing the very high energy emission (VHE, >100 GeV) in these extreme microquasars is critical to understanding their contribution to the origin of galactic cosmic rays. The 2020 giant outburst of this system, where X-ray fluxes exceeded 12 Crab, marked a rare opportunity to investigate the gamma-ray and rapid optical variability of these transient systems while in such an extreme state. This month of activity marked the brightest flare measured in this system. VERITAS's developing optical capabilities in tandem with the ability to measure TeV gamma rays allowed for a unique campaign to be undertaken. VERITAS's observations of this system during the outburst will be presented in the context of observations at lower energies and previous observations of this system by imaging atmospheric Cherenkov telescopes.
Published: 2021

8. Gamma-ray and Optical Observations of Repeating Fast Radio Bursts with VERITAS

Author: Matthew Lundy, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Weidong Jin, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Millisecond, Fast radio burst, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Theoretical models, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Magnetar, Radio telescope, Rapid rise, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Fast radio burst (FRBs) are an exciting class of bright, extragalactic, millisecond radio transients. The recent development of large field-of-view (FOV) radio telescopes has caused a rapid rise in the number of identified single burst and repeating FRBs. This has allowed for the extensive multi-wavelength follow-up to search for the potential counterparts predicted by theoretical models. New observations of similar radio transients in Galactic magnetars like SGR 1935+2154 have continued to motivate the search for rapid optical and very-high-energy (VHE, >100 GeV) counterparts. Since 2016 VERITAS has engaged in an FRB observing campaign to search for the prompt optical, and VHE emission from multiple repeating FRBs. We present these new results from VERITAS observations of five repeating sources including data taken simultaneously with bursts observed by the CHIME radio telescope.
Published: 2021

9. Multi-Messenger observations of the Fermi-LAT blazar 4FGL J0658.6+0636 consistent with an IceCube high-energy neutrino

Author: David R. Williams, Antoine Kouchner, K. A. Farrell, Alasdair E. Gent, V. V. Vassiliev, Fabian Schüssler, H. A. Peña-Herazo, Georgios Paraschos, R. Shang, D. S. Hanna, Q. Feng, John L. Quinn, D. Ribeiro, Daniel Nieto, A. Brill, Giacomo Bonnoli, M. Kertzman, Lucy Fortson, Yong Sheng, Olivier Hervet, T. B. Humensky, Francesco Massaro, S. O'Brien, Alessio Berti, M. J. Lang, donggeun tak, Teddy Cheung, Suvi Gezari, Joern Wilms, A. D. Falcone, P. T. Reynolds, Miguel Perez-Torres, Andrea Tramacere, Reshmi Mukherjee, G. M. Foote, Binita Hona, C. Giuri, Raniere de Menezes, P. Kaaret, I. Sadeh, Frank J. Masci, Emilio Fernandez-Garcia, W. Jin, Wystan Benbow, Uwe Bach, R. R. Prado, P. Moriarty, Jonas Heßdörfer, M. Pohl, Matthias Kadler, Steven Hämmerich, Gernot Maier, G. H. Sembroski, Andrea Gokus, R. A. Ong, M. Capasso, Ivan Agudo, Marcos Santander, C. E. McGrath, T. J. Williamson, A. J.R. Weinstein, E. Roache, A. Archer, Jorge Otero-Santos, Simone Garrappa, Alex Kraus, G. H. Gillanders, A. J. Castro-Tirado, Alexis Coleiro, Jodi Christiansen, Jamie Holder, K. Ragan, Meenakshi Rajagopal, A. N. Otte, Alessandro Paggi, K. Pfrang, Orel Gueta, Marcello Giroletti, Cristina Nanci, Javier Moldon, M. Nievas-Rosillo, Elisa Bernardini, C. Adams, Werner Colmar, Y. D. Hu, J. A. Ryan, Richard Walters, M. Lundy, Florian Eppel, Tobias Kleiner, R. Sanchez-Ramirez, J. H. Buckley, A. J. Chromey, Amy Furniss, Charlotte Ward, Konstancja Satalecka, E. Pueschel, Manel Errando, Sara Buson, S. Kumar, S. Patel, M. D. Caballero-Garcia, and Marco Ajello
Subjects: Physics, High energy, Astrophysics, Neutrino, Blazar, Fermi Gamma-ray Space Telescope
Published: 2021

10. Performance of a proposed event-type based analysis for CTA

Author: Tarek M. Hassan, Maximilian Nöthe, Gernot Maier, Ievgen Vovk, Michele Peresano, Orel Gueta, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), CTA Consortium, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cherenkov Telescope Array, Computer science, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, energy resolution, GeV, VHE, GLAST, Set (abstract data type), Observatory, TeV, ddc:530, Sensitivity (control systems), [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Event (probability theory), Astroparticle physics, Monte Carlo [numerical calculations], sensitivity, observatory, gamma ray, quality, numerical calculations: Monte Carlo, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Algorithm, Energy (signal processing), performance
Abstract: 37th International Cosmic Ray Conference, ICRC 2021, Berlin, online, Germany, 12 Jul 2021 - 23 Jul 2021; Proceedings of Science / International School for Advanced Studies (ICRC2021), 752 (2021). doi:10.22323/1.395.0752, The Cherenkov Telescope Array (CTA) will be the next-generation observatory in the field of very-high-energy (20 GeV to 300 TeV) gamma-ray astroparticle physics. Classically, data analysis in the field maximizes sensitivity by applying quality cuts on the data acquired. These cuts, optimized using Monte Carlo simulations, select higher quality events from the initial dataset. Subsequent steps of the analysis typically use the surviving events to calculate one set of instrument response functions (IRFs). An alternative approach is the use of event types, as implemented in experiments such as the Fermi-LAT. In this approach, events are divided into sub-samples based on their reconstruction quality, and a set of IRFs is calculated for each sub-sample. The sub-samples are then combined in a joint analysis, treating them as independent observations. This leads to an improvement in performance parameters such as sensitivity, angular and energy resolution. Data loss is reduced since lower quality events are included in the analysis as well, rather than discarded. In this study, machine learning methods will be used to classify events according to their expected angular reconstruction quality. We will report the impact on CTA high-level performance when applying such an event-type classification, compared to the classical procedure., Published by SISSA, Trieste
Published: 2021

11. Status of the VERITAS Stellar Intensity Interferometry (VSII) System

Author: P. Moriarty, Alasdair E. Gent, James Ryan, R. Shang, Daniel Nieto, E. Roache, M. Capasso, M. Kertzman, T. J. Williamson, Davis Jonathan, David R. Williams, K. Ragan, S. O'Brien, Wystan Benbow, M. J. Lang, Marcos Santander, P. Kaaret, M. Pohl, Reshmi Mukherjee, C. E. McGrath, I. Sadeh, A. Brill, K Matthews Nolan, A. J.R. Weinstein, Jamie Holder, C. Giuri, Q. Feng, John L. Quinn, A. Archer, D. Ribeiro, M. Nievas-Rosillo, Sameer Patel, Orel Gueta, A. D. Falcone, Manel Errando, G. H. Sembroski, Gernot Maier, S. Kumar, R. R. Prado, D. S. Hanna, C. B. Adams, David Kieda, T. B. Humensky, S. Patel, LeBohec Tugdual, R. A. Ong, G. H. Gillanders, Olivier Hervet, K. A. Farrell, V. V. Vassiliev, Lisa Mike, Lucy Fortson, Jodi Christiansen, Tobias Kleiner, G. M. Foote, J. H. Buckley, A. J. Chromey, donggeun tak, A. N. Otte, K. Pfrang, W. Jin, M. Lundy, Binita Hona, Amy Furniss, E. Pueschel, and P. T. Reynolds
Subjects: Physics, Interferometry, Astronomy, Intensity (physics)
Published: 2021

12. Very High Energy Gamma-ray Emission from the Binary System LS I +61 303

Author: G. M. Foote, S. O'Brien, W. Jin, Tobias Kleiner, R. Shang, Orel Gueta, R. R. Prado, P. Kaaret, P. T. Reynolds, E. Pueschel, John L. Quinn, I. Sadeh, C. B. Adams, James Ryan, D. Ribeiro, David R. Williams, M. Pohl, Gernot Maier, Jodi Christiansen, Q. Feng, T. B. Humensky, M. Lundy, Marcos Santander, Lucy Fortson, P. Moriarty, Olivier Hervet, C. E. McGrath, M. Capasso, M. Kertzman, A. J.R. Weinstein, A. Brill, A. N. Otte, Daniel Nieto, David Kieda, T. J. Williamson, K. Pfrang, Manel Errando, S. Kumar, R. A. Ong, S. Patel, G. H. Sembroski, J. H. Buckley, M. Nievas-Rosillo, Binita Hona, D. S. Hanna, K. A. Farrell, V. V. Vassiliev, Sameer Patel, donggeun tak, Amy Furniss, A. Archer, E. Roache, A. J. Chromey, G. H. Gillanders, Reshmi Mukherjee, C. Giuri, Alasdair E. Gent, K. Ragan, M. J. Lang, A. D. Falcone, Jamie Holder, and Wystan Benbow
Subjects: Physics, High energy, Gamma ray, Binary system, Computational physics
Published: 2021

13. VERITAS Observations of the Galactic Center Region at Multi-TeV Gamma-Ray Energies

Author: S. O'Brien, donggeun tak, E. Roache, K. A. Farrell, V. V. Vassiliev, John L. Quinn, D. Ribeiro, J. H. Buckley, K. Ragan, P. Kaaret, A. Archer, A. J. Chromey, M. Nievas-Rosillo, G. H. Gillanders, Reshmi Mukherjee, David Kieda, Jodi Christiansen, C. Giuri, James M. Ryan, M. Kertzman, Olivier Hervet, Amy Furniss, A. Brill, I. Sadeh, Lucy Fortson, Marcos Santander, Binita Hona, D. S. Hanna, M. J. Lang, E. Pueschel, Wystan Benbow, A. D. Falcone, Orel Gueta, Q. Feng, P. Moriarty, M. Capasso, W. Jin, Daniel Nieto, Gernot Maier, Martin Pohl, T. J. Williamson, A. N. Otte, C. E. McGrath, K. Pfrang, A. J.R. Weinstein, R. Shang, P. T. Reynolds, G. M. Foote, Jamie Holder, R. A. Ong, R. R. Prado, David A. Williams, Tobias Kleiner, G. H. Sembroski, J. A. Ryan, M. Lundy, C. Adams, T. B. Humensky, Manel Errando, S. Kumar, S. Patel, and Alasdair E. Gent
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Supermassive black hole, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, law.invention, Telescope, Sagittarius A, law, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, Cherenkov radiation, Zenith
Abstract: The Galactic Center region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. We present the analysis of the very-high-energy gamma-ray emission above 2 TeV of the region around the Galactic Center known as the Central Molecular Zone using 125 hours of data taken with the VERITAS imaging-atmospheric Cherenkov telescope between 2010 and 2018. This analysis employs new shower reconstruction algorithms and instrument response functions optimized for data taken at large zenith angles such as the Galactic Center sources. We report positions and spectra for point sources VER J1745-290, G0.9+0.1, and HESS J1746-285, along with a light curve for VER J1745-290, the brightest source in the region consistent with the position of the supermassive black hole Sagittarius A*. We also measure the spectrum of the diffuse emission from the Galactic Center ridge region, which has been claimed as evidence of a Galactic PeVatron., Contribution to the Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021), Berlin, Germany
Published: 2021

14. The VERITAS-Stellar Intensity Interferometry (VSII) survey of Stellar Diameters

Author: James Ryan, Wystan Benbow, Mike Lisa, G. M. Foote, P. Moriarty, C. B. Adams, Lucy Fortson, Amy Furniss, Q. Feng, R. A. Ong, P. T. Reynolds, M. Capasso, M. Kertzman, Manel Errando, E. Pueschel, Orel Gueta, Daniel Nieto, T. J. Williamson, S. Kumar, T. B. Humensky, M. Nievas-Rosillo, G. H. Sembroski, S. Patel, Nolan Matthews, Sameer Patel, Alasdair E. Gent, J. H. Buckley, A. N. Otte, D. S. Hanna, Marcos Santander, M. Lundy, Tugdual LeBohec, P. Kaaret, A. Archer, K. Pfrang, Gernot Maier, A. J. Chromey, S. O'Brien, Binita Hona, C. E. McGrath, donggeun tak, Olivier Hervet, David R. Williams, Reshmi Mukherjee, A. Brill, G. H. Gillanders, A. J.R. Weinstein, Jonathan Davis, Jodi Christiansen, I. Sadeh, C. Giuri, R. Shang, Tobias Kleiner, E. Roache, David Kieda, M. Pohl, K. Ragan, K. A. Farrell, V. V. Vassiliev, John L. Quinn, D. Ribeiro, R. R. Prado, W. Jin, Jamie Holder, M. J. Lang, and A. D. Falcone
Subjects: Telescope, Physics, Interferometry, Stars, Cardinal point, Optical wavelength, law, IACT, Astrophysics, Cherenkov radiation, Intensity (physics), law.invention
Abstract: The VERITAS Imaging Air Cherenkov Telescope (IACT) array was augmented in 2019 with high-speed focal plane electronics to allow its use for Stellar Intensity Interferometry (SII) observations. Since January 2019, The VERITAS Stellar Interferometer (VSII) recorded more than 250 hours of moonlit observations on 39 different bright stars and binary systems ($m_V < 3.74$ ) at an effective optical wavelength of 416 nm. These observations resulted in the measurement of the diameters of several stars with better than 5\% resolution. This talk will describe the status of the VSII survey and analysis.
Published: 2021

15. VERITAS Observations of the Galactic Center Region at Multi-TeV Gamma-Ray Energies

Author: G. H. Sembroski, M. Lundy, P. Moriarty, Lucy Fortson, T. B. Humensky, S. Schlenstedt, Martin Pohl, Gernot Maier, Alasdair E. Gent, M. K. Daniel, Manel Errando, S. P. Wakely, A. Weinstein, J. P. Finley, Reshmi Mukherjee, M. Kertzman, C. Giuri, Jodi Christiansen, K. Ragan, Robert Brose, P. Kaaret, A. N. Otte, A. D. Falcone, K. Pfrang, Marcos Santander, D. S. Hanna, R. Shang, Wystan Benbow, David Kieda, G. H. Gillanders, Olivier Hervet, R. R. Prado, M. Buchovecky, John L. Quinn, D. Ribeiro, S. O'Brien, E. Roache, David A. Williams, R. A. Ong, S. Kumar, A. Brill, Daniel Nieto, Q. Feng, Amy Furniss, James Ryan, F. Krennrich, P. T. Reynolds, M. Nievas-Rosillo, E. Pueschel, B. Stevenson, A. J. Chromey, C. B. Adams, G. Hughes, Jamie Holder, M. J. Lang, Gordon T. Richards, N. Kelley-Hoskins, W. Jin, and M. Capasso
Subjects: 010504 meteorology & atmospheric sciences, accelerator, High-energy astronomy, Astrophysics::High Energy Astrophysical Phenomena, atmosphere [Cherenkov counter], VHE [gamma ray], FOS: Physical sciences, Cosmic ray, Astrophysics, power spectrum, 01 natural sciences, emission [gamma ray], HESS, 0103 physical sciences, supernova, black hole, TeV, cloud, composite, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Supermassive black hole, Spectral index, background, Galactic Center, Gamma ray, Astronomy and Astrophysics, Light curve, flux, Supernova, 13. Climate action, Space and Planetary Science, cosmic radiation, ddc:520, VERITAS, galaxy, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. The inner 375 pc x 600 pc region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants. We present the results of our improved analysis of the very-high-energy (VHE) gamma-ray emission above 2 TeV from the GC using 125 hours of data taken with the VERITAS imaging-atmospheric Cherenkov telescope between 2010 and 2018. The central source VER J1745-290, consistent with the position of Sagittarius A*, is detected at a significance of 38 standard deviations above the background level $(38\sigma)$, and we report its spectrum and light curve. Its differential spectrum is consistent with a power law with exponential cutoff, with a spectral index of $2.12^{+0.22}_{-0.17}$, a flux normalization at 5.3 TeV of $1.27^{+0.22}_{-0.23}\times 10^{-13}$ TeV-1 cm-2 s-1, and cutoff energy of $10.0^{+4.0}_{-2.0}$ TeV. We also present results on the diffuse emission near the GC, obtained by combining data from multiple regions along the GC ridge which yield a cumulative significance of $9.5\sigma$. The diffuse GC ridge spectrum is best fit by a power law with a hard index of 2.19 $\pm$ 0.20, showing no evidence of a cutoff up to 40 TeV. This strengthens the evidence for a potential accelerator of PeV cosmic rays being present in the GC. We also provide spectra of the other sources in our field of view with significant detections, composite supernova remnant G0.9+0.1 and HESS J1746-285., Comment: 19 pages, 8 figures, Accepted for publication in Astrophysical Journal
Published: 2021

16. Effect of the uncertainty in the hadronic interaction models on the estimation of the sensitivity of the Cherenkov telescope array

Author: Vitor de Souza, Luisa Arrabito, J. Bregeon, Takanori Yoshikoshi, Abelardo Moralejo Olaizola, Gernot Maier, Michiko Ohishi, Luan B. Arbeletche, Konrad Bernlöhr, Laboratoire Univers et Particules de Montpellier (LUPM), 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: interaction [cosmic radiation], Cherenkov Telescope Array, interaction: model, current: hadronic, atmosphere [Cherenkov counter], Monte Carlo method, pi, IACT, GeV, cosmic radiation: interaction, cosmic radiation [charged particle], 01 natural sciences, charged particle: cosmic radiation, HESS, AMS, cosmic radiation: VHE, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, COSMIC cancer database, model [interaction], Astrophysics::Instrumentation and Methods for Astrophysics, imaging, Monte Carlo [numerical calculations], CERN LHC Coll, DAMPE, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, numerical calculations: Monte Carlo, atmosphere [showers], Nuclear and High Energy Physics, air, Astrophysics::High Energy Astrophysical Phenomena, energy spectrum, FOS: Physical sciences, Cosmic ray, Cherenkov counter: atmosphere, GLAST, Nuclear physics, VHE [cosmic radiation], hadronic [current], 0103 physical sciences, TeV, ddc:530, Sensitivity (control systems), [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], electromagnetic component, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, showers: atmosphere, 010308 nuclear & particles physics, nucleus, sensitivity, MAGIC, Air shower, 13. Climate action, gamma ray, hadron, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], RAIOS CÓSMICOS
Abstract: Imaging Atmospheric Cherenkov Telescopes (IACTs) are ground-based indirect detectors for cosmic gamma rays with energies above tens of GeV. The major backgrounds for gamma-ray observations in IACTs are cosmic-ray charged particles. The capability to reject these backgrounds is the most important factor determining the gamma-ray sensitivity of IACT systems. Monte Carlo simulations are used to estimate the residual background rates and sensitivity of the systems during the design and construction phase. Uncertainties in the modeling of high-energy hadronic interactions of cosmic rays with nuclei in the air propagate into the estimates of residual background rates and subsequently into the estimated instrument sensitivity. We investigate the influence of the difference in the current hadronic interaction models on the estimated gamma-ray sensitivity of the Cherenkov Telescope Array using four interaction models (QGSJET-II-03, QGSJET-II-04, EPOS-LHC, and SIBYLL2.3c) implemented in the air shower simulation tool CORSIKA. Variations in background rates of up to a factor 2 with respect to QGSJET-II-03 are observed between the models, mainly due to differences in the $\pi^0$ production spectrum. These lead to ~30% differences in the estimated gamma-ray sensitivity in the 1 - 30 TeV region, assuming a 50-hour observation of a gamma-ray point-like source. The presented results also show that IACTs have a significant capability in the verification of hadronic interaction models., Comment: 23 pages, 10 figures, accepted for publication in JPhysG
Published: 2021

17. VERITAS follow-up observation of the blazar TXS 0506+056

Author: Weidong Jin, RileyAnne Sharpe, Massimo Capasso, Rene Ong, Iftach Sadeh, Philip Kaaret, Wystan Benbow, Reshmi Mukherjee, Raul Prado, Matthew Lundy, Sameer Patel, Patrick Moriarty, Gernot Maier, Amy Furniss, Ken Ragan, David Williams, James Buckley, Lucy Fortson, John Quinn, Jamie Holder, Chiara Giuri, Elisa Pueschel, Daniel Nieto, Colin Adams, Stephan O'Brien, Deivid Ribeiro, Konstantin Pfrang, Orel Gueta, Gregory M Foote, Amanda Weinstein, Sajan Kumar, Tyler Williamson, Donggeun Tak, Conor McGrath, Tobias Kai Kleiner, Martin Pohl, Paul Reynolds, Binita Hona, David Hanna, Marcos Santander, Glenn Sembroski, Sonal Ramesh Patel, Manel Errando, Mary Kertzman, Olivier Hervet, Mireia Nievas-Rosillo, Mark Lang, Emmet Roache, Thomas Brian Humensky, Ruo-Yu Shang, Vladimir Vassiliev, Alisha Chromey, Abe Falcone, Jodi Christiansen, Adam Otte, Alasdair E. Gent, Aryeh Brill, James Ryan, Kayla Farrell, Gary Gillanders, Qi Feng, Avery Archer, and David Kieda
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High energy, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 13. Climate action, Observatory, QUIET, Neutrino, Astrophysics - High Energy Astrophysical Phenomena, Blazar, Event (particle physics)
Abstract: The gamma-ray blazar TXS 0506+056 was found with an enhanced gamma-ray emission state in spatial and temporal coincidence with the IceCube high energy neutrino event IC170922A. This is the most significant association by far between a high-energy neutrino event and a blazar in a flaring state. Studying the time evolution and spectral behavior of the blazar emission may help in identifying the sources of the diffuse neutrino flux observed by IceCube and the origin of energetic cosmic rays. TXS 0506+056 was detected by the VERITAS gamma-ray observatory with a significance of 5.8 standard deviations above 110 GeV in a 35 hour data set collected between September 23, 2017 and February 6, 2018. Here we will present results from recent VERITAS observations and an associated multiwavelength campaign, collected between October 10, 2018 to March 1, 2021. A relatively quiet very high energy gamma-ray emission state was observed during this time period, and flux upper limits are used to constrain the potential variability of this blazar.
Published: 2021
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18. Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Author: Masanori Nakamura, R. Shang, Abelardo Moralejo, A. Rugliancich, Marina Manganaro, Jun Liu, Monika Moscibrodzka, Andreas Specovius, V. Ramakrishnan, S. O'Brien, Michal Ostrowski, Luis C. Ho, Sera Markoff, D. Depaoli, I. Jung-Richardt, Manel Errando, Chiara Righi, S. Panny, Toshiaki Inada, Alexandra J. Tetarenko, Daniela Dorner, Norbert Wex, Nimesh A. Patel, Olivier Hervet, C. Arcaro, Alasdair E. Gent, Yu Wun Wong, Gaia Vanzo, Pierre Brun, Konstancja Satalecka, Stefan Funk, Lorenzo Bellizzi, Michael Lindqvist, Michele Doro, Felix Jankowsky, P. Kaaret, Nicholas R. MacDonald, Lang Cui, P. Temnikov, S. Patel, Sabrina Einecke, Manuel Artero, E. Moretti, Hope Boyce, M. Gaug, Charles F. Gammie, Iryna Lypova, Gisela N. Ortiz-León, Felix Aharonian, Colin J. Lonsdale, Buell T. Jannuzi, Gavin Rowell, M. Bryan, Yvonne Becherini, Aleksandar Popstefanija, M. Pohl, A. Marcowith, Jean-Pierre Ernenwein, H. Alyson Ford, Wystan Benbow, Karen E. Williamson, Daryl Haggard, Hambeleleni Ndiyavala, Tod R. Lauer, Arnaud Mares, Chaitanya Priyadarshi, Michael Punch, Helge Rottmann, J. Zorn, D. Dominis Prester, Bernd Schleicher, M. Minev, Hector Olivares, Ciriaco Goddi, S. Pita, J. Herrera, Alessia Spolon, Léa Jouvin, Na Wang, G. Martí-Devesa, Tomohiko Oka, Kirsty Feijen, E. Do Souto Espiñeira, Ralph Eatough, Johannes Veh, Stefano Gabici, Tomislav Terzić, D. Glawion, Gilles Fontaine, Bradford Benson, C. B. Rulten, Jenni Jormanainen, Jason SooHoo, Michael Titus, Jose Miguel Delgado, Marcos López-Moya, Freek Roelofs, Wlodek Bednarek, M. Lundy, Richard Anantua, Alessandra Lamastra, P. T. Reynolds, Vassil Verguilov, M. Lemoine-Goumard, G. Fichet de Clairfontaine, L. Di Venere, Michael Kreter, Jose Miguel Miranda, Alan L. Roy, Yating Chai, A. López-Oramas, M. Tluczykont, Jacek Niemiec, R. Konno, Tyler Trent, Olaf Reimer, Heino Falcke, Amanpreet Kaur, M. Panter, Narek Sahakyan, Kasper B. Schmidt, A. Carosi, K. Egberts, L. Maraschi, Stefan Cikota, V. Joshi, Koji Noda, Elisa Bernardini, Ye-Fei Yuan, Garrett K. Keating, Fumie Tazaki, Pawel Gliwny, M. Vazquez Acosta, Nicola Giglietto, M. Capasso, Vincent Piétu, Satoshi Fukami, Roman Gold, Elina Lindfors, Satoki Matsushita, A. Lemiere, F. Eichhorn, U. Katz, Yoshinori Yonekura, N. Shafi, Natalia Żywucka, Michael Kramer, M. Palatiello, Daniel Mazin, Samuel Timothy Spencer, Victoria Moreno, Oliver Porth, Julian Sitarek, Kazi L.J. Rygl, Wen Ping Lo, Geoffrey C. Bower, Ilje Cho, S. Fegan, Samuel Zouari, J. M. Paredes, V. Fallah Ramazani, Thomas Murach, Jim Hinton, R. J. White, F. Leone, S. Loporchio, M. de Naurois, Ed Fomalont, Bart Ripperda, Dominique Broguiere, J. Becerra González, Joseph R. Farah, Q. Feng, Andreas Quirrenbach, Taehyun Jung, C. Trichard, Masahiro Teshima, Domenico Tiziani, D. Malyshev, Richard Plambeck, Lynn D. Matthews, Avery E. Broderick, S. Kumar, T. J. Williamson, M. K. Daniel, Sylvia Zhu, P. J. Meintjes, Tjark Miener, Jodi Christiansen, Roger Brissenden, S. Sailer, Dmitry Khangulyan, David Paneque, Thomas P. Krichbaum, Sergey S. Savchenko, Angelo Ricarte, Riaan Steenkamp, T. Chand, J. Dyks, Francesco Dazzi, V. Baghmanyan, Zorawar Wadiasingh, Kazunori Akiyama, Stefan Ohm, C. Levy, Giovanna Ferrara, Makoto Inoue, Jhilik Majumdar, Nobuyuki Sakai, Dieter Horns, Jorge A. Preciado-López, Cornelia Müller, G. Hermann, Regis Terrier, A. J. Chromey, Dominic W. Pesce, Felix M. Pötzl, Mark Gurwell, Alejandro Cruz-Osorio, Ivan Marti-Vidal, Ben Prather, Tom Armstrong, Jongho Park, Matteo Cerruti, Ziri Younsi, Amy Furniss, Chih-Wei Locutus Huang, Lijing Shao, A. Djannati-Ataï, Shoko Koyama, D. Gottschall, P. Vincent, A. Brill, Kenji Toma, Antonios Nathanail, M. Nievas-Rosillo, M. Seglar-Arroyo, C. Delgado Mendez, Mahito Sasada, G. Busetto, Maciek Wielgus, Marcos Santander, Doosoo Yoon, D. A. Sanchez, Hiroki Okino, Christo Venter, Christiaan D. Brinkerink, James Ryan, S. Mićanović, Raquel Fraga-Encinas, Mark G. Rawlings, G. H. Sembroski, G. Principe, Xiang Liu, Karl Friedrich Schuster, Ronald Hesper, L. Sun, Ciro Bigongiari, Ramesh Narayan, M. Strzys, L. Mohrmann, Daniel R. van Rossum, Y. Ohtani, Wu Jiang, Luciano Rezzolla, Nu. Komin, V. A. Acciari, Katherine L. Bouman, Jürgen Besenrieder, Clemens Hoischen, A. A. Zdziarski, Antonio Tutone, Hung Yi Pu, A. Arbet Engels, J.-P. Lenain, A. De Angelis, Tomoya Hirota, R. J. García López, Carlo Romoli, Werner Hofmann, Tuomas Savolainen, Neil M. Nagar, Minfeng Gu, M. Karjalainen, Vitaly Neustroev, A. N. Otte, John F. C. Wardle, Tomoaki Oyama, Jongsoo Kim, Monica Barnard, J. Otero-Santos, R. D. Parsons, Pierre Christian, A. Priyana Noel, A. S. Seyffert, Shami Chatterjee, E. O. Angüner, David A. Green, Ramesh Karuppusamy, Zhiyuan Li, J. Devin, Dominik Elsaesser, F. Giordano, Santiago Ubach, Michael A. Nowak, Y. Kobayashi, F. Di Pierro, Iniyan Natarajan, A. Zech, M. Garczarczyk, Dmitriy Kostunin, Michael Janssen, Giacomo Bonnoli, Mariafelicia De Laurentis, Kuo Liu, G. Emery, Yutaro Kofuji, Antxon Alberdi, Marco Toliman Lucchini, R. A. Ong, Catherine Boisson, Daniel C. M. Palumbo, Stefan Klepser, Stefano Covino, Motoki Kino, Daniel Kerszberg, C. Armand, Maria Haupt, D. Zarić, K. Pfrang, R. López-Coto, M. Zacharias, Jae-Young Kim, Sheperd S. Doeleman, U. Barres de Almeida, Pratik Majumdar, M. V. Fonseca, Mosè Mariotti, G. Lamanna, Alexander Hahn, Sidika Merve Colak, R. J. Tuffs, B. Bi, Juan-Carlos Algaba, L. Oakes, D. Jankowsky, Y. Kajiwara, R. Marx, Bošnjak, John E. Barrett, Kotaro Niinuma, F. D'Ammando, Qingwen Wu, A. Yusafzai, Christian M. Fromm, Chi-kwan Chan, B. De Lotto, M. Kertzman, Manuela Mallamaci, H. Prokoph, Tadayuki Takahashi, Damir Lelas, Victor Doroshenko, E. Kasai, Lea Heckmann, Bong Won Sohn, Francesco Gabriele Saturni, Shiro Ikeda, T. Vuillaume, Laurent Loinard, G. Maurin, M. Füßling, Martin Will, Yi Chen, Gianluca Giavitto, Remo P. J. Tilanus, M. Spir-Jacob, Alessandro Montanari, Thomas Lohse, Tihomir Surić, J. van Scherpenberg, Per Friberg, He Sun, Luca Tosti, Kiyoaki Wajima, E. Ruiz-Velasco, Thomas Bylund, M. Balokovic, Feng Yuan, S. Nozaki, Mischa Breuhaus, Peter Galison, Y. A. Gallant, L. Olivera-Nieto, Dorota Sobczyńska, Maria-Isabel Bernardos, R. Rauth, Izumi Mizuno, Vincent L. Fish, S. G. Jorstad, Tomoki Saito, Giovanni Ceribella, Jacques Muller, J. P. Finley, Stefano Ansoldi, Boris Georgiev, Marcello Giroletti, Arturo I. Gómez-Ruiz, Karl M. Menten, Aristeidis Noutsos, P. deWilt, Junhan Kim, Alejandro Mus Mejías, Q. Remy, Dong-Jin Kim, P. G. Prada Moroni, Robert Wharton, Riccardo Paoletti, R. R. Prado, Zhi-Qiang Shen, S. Paiano, S. Chandra, Andrés Baquero, Anna Barnacka, Lucy Fortson, Wrijupan Bhattacharyya, Marc Ribó, E. de Ona Wilhelmi, Paul T. P. Ho, Yan-Rong Li, Derek Ward-Thompson, M. Scalici, G. Maneva, Constantin Steppa, Dimitrios Psaltis, A.M. Taylor, J. Damascene Mbarubucyeye, Daniel P. Marrone, Karl Mannheim, W. Boland, P. Morris, D. A. Prokhorov, M. Mohamed, Katsuaki Asano, Gernot Maier, Kotaro Moriyama, H. Odaka, M. Büchele, E. Pueschel, Kazuyoshi Nishijima, Christopher J. Duffy, H. M. Schutte, Camilla Maggio, Mark Kettenis, V. D'Elia, Saverio Lombardi, Ramprasad Rao, Ivica Puljak, R. Mirzoyan, V. Sahakian, Guang Yao Zhao, Adrian Biland, F. Werner, Rafal Moderski, Olivier Gentaz, Ullrich Schwanke, James M. Moran, S. Komossa, Yuzhu Cui, A. Jiménez-Rosales, Arash Roshanineshat, S. Ventura, Lindy Blackburn, David J. James, G. Hughes, Hidetoshi Kubo, Mansour Karami, José L. Gómez, P. Reichherzer, Davit Zargaryan, Paul Tiede, Koushik Chatterjee, Chunchong Ni, Roger Deane, Axel Donath, J. Rico, A. W. Chen, A. Fiasson, Jun Yi Koay, T. B. Humensky, Satoko Sawada-Satoh, Isak Delberth Davids, Alan P. Marscher, Alan E. E. Rogers, Rebecca Azulay, Kazuma Ishio, Paul M. Chesler, D. M. Strom, Carlo Vigorito, Marek Jamrozy, G. Pühlhofer, M. de Bony de Lavergne, Roberta Zanin, T. Schweizer, Elisa Prandini, Helene Sol, Rodolfo Carosi, M. Hörbe, T. Tavernier, Mareki Honma, M. Holler, Gordon T. Richards, Armelle Jardin-Blicq, Paolo Marchegiani, Sang-Sung Lee, D. Huber, Ashot Chilingarian, Nikola Godinovic, F. Ait Benkhali, Jason Dexter, Do-Young Byun, Anton Dmytriiev, Massimo Persic, Alicia Fattorini, L. Dirson, Cosimo Nigro, E. Roache, Sargis Gasparyan, S. Schwemmer, Sara Issaoun, Jessica Dempsey, Andrea Santangelo, Włodek Kluźniak, Mel Rose, Huib Jan van Langevelde, D. J. van der Walt, Elisabetta Liuzzo, A. Stamerra, John Hoang, Michelle Tsirou, Wolfgang Rhode, Tomohisa Kawashima, L. A. Antonelli, Carolin Wunderlich, Keiichi Asada, David A. Williams, Joachim Hahn, P. Moriarty, T. M. Crawford, P. Da Vela, L. Rinchiuso, E. Molina, F. Peter Schloerb, Lovro Pavletić, S. Steinmassl, Des Small, Christoph Deil, Stefano Menchiari, Dan Bintley, K. Nakashima, Alice Donini, David H. Hughes, Heinrich J. Völk, Mohanraj Senniappan, K. A. Farrell, M. Renaud, J. A. Barrio, Miriam Lucio Martinez, Rachel Simoni, P. T. O'Brien, E. Colombo, V. Barbosa Martins, M. Orienti, Efthalia Traianou, Lluis Font, B. Machado de Oliveira Fraga, Y. Suda, J. Neilsen, John Conway, Eduardo Ros, Gibwa Musoke, Tarek M. Hassan, J. Bolmont, A. Sinha, Halim Ashkar, M.-H. Grondin, Daniel Nieto, Lab Saha, Fabrizio Tavecchio, Hyunwook Ro, Michael H. Hecht, Markus Böttcher, Antonio Fuentes, Simone Mender, Moritz Hütten, Ue-Li Pen, Yosuke Mizuno, Gopal Narayanan, Lei Huang, H. Abdalla, M. A. Kastendieck, Nicola Marchili, I. Snidaric, S. Sánchez, G. Vasileiadis, Kari Nilsson, Alexander W. Raymond, Greg Lindahl, Gregory Desvignes, Sascha Trippe, Sanae Inoue, Giacomo D'Amico, W. Jin, B. van Soelen, Andrew Chael, Anne Kathrin Baczko, Shunsuke Sakurai, L. Giunti, A. Nayerhoda, Walter Alef, Jamie Holder, Stefano Truzzi, Pablo Peñil, M. J. Lang, Francois Brun, Frank M. Rieger, V. Vitale, George N. Wong, Jirong Mao, S. Caroff, J. Kushida, André Young, Ru-Sen Lu, Daniel Morcuende, Jose Luis Contreras, Kazuhiro Hada, Juan Cortina, C. van Eldik, Pablo Torne, Raymond Blundell, Jarred Gershon Green, C. B. Adams, James M. Cordes, Jonathan Weintroub, Q. Piel, A. Berti, James E. M. Watson, G. Peron, Ken Young, Garret Cotter, Dario Hrupec, Jonathan Mackey, K. Ragan, John E. Carlstrom, Michael Backes, Tim Holch, D. Hadasch, Stawarz, F. Niederwanger, Feryal Özel, Lia Medeiros, A. Weinstein, Mitsunari Takahashi, Manuel Delfino, C. Y. Kuo, Aviad Levis, Francesco Longo, K. Kosack, Konrad Bernlöhr, Jacco Vink, C. Moore, Michael Bremer, Jim Davies, Jadyn Anczarski, Patrick M. Koch, Sabrina Casanova, Ming-Tang Chen, B. Peyaud, Christian Stegmann, Stefan Wagner, C. Perennes, Yasunobu Uchiyama, David Kieda, Chet Ruszczyk, Hiroshi Nagai, M. Curyło, Andrei Lobanov, Ana Babić, E. Moulin, Tomasz Bulik, Britton Jeter, I. Vovk, Martin Makariev, C. van Rensburg, Oscar Blanch, Rocco Lico, Silke Britzen, Misao Sasaki, A. Reimer, V. Poireau, R. Adam, David Ball, Mark Reynolds, D. Miceli, John L. Quinn, Roberto Garcia, J. F. Glicenstein, D. Ribeiro, A. Wierzcholska, Geoffrey B. Crew, Bruno Khelifi, David Sánchez-Arguelles, Ilse van Bemmel, Michael D. Johnson, J. Anton Zensus, Dominik Baack, Manuel Meyer, E. V. Kravchenko, I. Jiménez, Thomas Bronzwaer, Reshmi Mukherjee, D. Berge, C. Giuri, Kleopas Shiningayamwe, Shan Shan Zhao, Yuki Iwamura, A. D. Falcone, Lenka Tomankova, Carsten Kramer, Jan Wagner, Christian Fruck, B. Rudak, Jordy Davelaar, V. Marandon, K. Katarzyński, Roberto Neri, The EHT MWL Science Working Group, Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Instituto de RadioAstronomía Milimétrica (IRAM), 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 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)), 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), 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), 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)-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), Groupe de Physique des Solides (GPS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL), Event Horizon Telescope, Fermi-LAT, H.E.S.S., MAGIC, VERITAS, EAVN, High Energy Astrophys. & Astropart. Phys (API, FNWI), API Other Research (FNWI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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 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), 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), 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), Algaba, Jc, Anczarski, J, Asada, K, Balokovic, M, Chandra, S, Cui, Yz, Falcone, Ad, Giroletti, M, Goddi, C, Hada, K, Haggard, D, Jorstad, S, Kaur, A, Kawashima, T, Keating, G, Kim, Jy, Kino, M, Komossa, S, Kravchenko, Ev, Krichbaum, Tp, Lee, S, Lu, R, Lucchini, M, Markoff, S, Neilsen, J, Nowak, Ma, Park, J, Principe, G, Ramakrishnan, V, Reynolds, Mt, Sasada, M, Savchenko, S, Williamson, Ke, Longo, F, Et, Al., University of Michigan, Department of Electronics and Nanoengineering, Aalto-yliopisto, Aalto University, Algaba, J. C., Anczarski, J., Asada, K., Balokovic, M., Chandra, S., Cui, Y. -Z., Falcone, A. D., Giroletti, M., Goddi, C., Hada, K., Haggard, D., Jorstad, S., Kaur, A., Kawashima, T., Keating, G., Kim, J. -Y., Kino, M., Komossa, S., Kravchenko, E. V., Krichbaum, T. P., Lee, S. -S., Lu, R. -S., Lucchini, M., Markoff, S., Neilsen, J., Nowak, M. A., Park, J., Principe, G., Ramakrishnan, V., Reynolds, M. T., Sasada, M., Savchenko, S. S., Williamson, K. E., Akiyama, K., Alberdi, A., Alef, W., Anantua, R., Azulay, R., Baczko, A. -K., Ball, D., Barrett, J., Bintley, D., Benson, B. A., Blackburn, L., Blundell, R., Boland, W., Bouman, K. L., Bower, G. C., Boyce, H., Bremer, M., Brinkerink, C. D., Brissenden, R., Britzen, S., Broderick, A. E., Broguiere, D., Bronzwaer, T., Byun, D. -Y., Carlstrom, J. E., Chael, A., Chan, C. -K., Chatterjee, S., Chatterjee, K., Chen, M. -T., Chen, Y., Chesler, P. M., Cho, I., Christian, P., Conway, J. E., Cordes, J. M., Crawford, T. M., Crew, G. B., Cruz-Osorio, A., Davelaar, J., De Laurentis, M., Deane, R., Dempsey, J., Desvignes, G., Dexter, J., Doeleman, S. S., Eatough, R. P., Falcke, H., Farah, J., Fish, V. L., Fomalont, E., Ford, H. A., Fraga-Encinas, R., Friberg, P., Fromm, C. M., Fuentes, A., Galison, P., Gammie, C. F., Garcia, R., Gentaz, O., Georgiev, B., Gold, R., Gomez, J. L., Gomez-Ruiz, A. I., Gu, M., Gurwell, M., Hecht, M. H., Hesper, R., Ho, L. C., Ho, P., Honma, M., Huang, C. -W. L., Huang, L., Hughes, D. H., Ikeda, S., Inoue, M., Issaoun, S., James, D. J., Jannuzi, B. T., Janssen, M., Jeter, B., Jiang, W., Jimenez-Rosales, A., Johnson, M. D., Jung, T., Karami, M., Karuppusamy, R., Kettenis, M., Kim, D. -J., Kim, J., Koay, J. Y., Kofuji, Y., Koch, P. M., Koyama, S., Kramer, M., Kramer, C., Kuo, C. -Y., Lauer, T. R., Levis, A., Li, Y. -R., Li, Z., Lindqvist, M., Lico, R., Lindahl, G., Liu, J., Liu, K., Liuzzo, E., Lo, W. -P., Lobanov, A. P., Loinard, L., Lonsdale, C., Macdonald, N. R., Mao, J., Marchili, N., Marrone, D. P., Marscher, A. P., Marti-Vidal, I., Matsushita, S., Matthews, L. D., Medeiros, L., Menten, K. M., Mizuno, I., Mizuno, Y., Moran, J. M., Moriyama, K., Moscibrodzka, M., Muller, C., Musoke, G., Mejias, A. M., Nagai, H., Nagar, N. M., Nakamura, M., Narayan, R., Narayanan, G., Natarajan, I., Nathanail, A., Neri, R., Ni, C., Noutsos, A., Okino, H., Olivares, H., Ortiz-Leon, G. N., Oyama, T., Ozel, F., Palumbo, D. C. M., Patel, N., Pen, U. -L., Pesce, D. W., Pietu, V., Plambeck, R., Popstefanija, A., Porth, O., Potzl, F. M., Prather, B., Preciado-Lopez, J. A., Psaltis, D., Pu, H. -Y., Rao, R., Rawlings, M. G., Raymond, A. W., Rezzolla, L., Ricarte, A., Ripperda, B., Roelofs, F., Rogers, A., Ros, E., Rose, M., Roshanineshat, A., Rottmann, H., Roy, A. L., Ruszczyk, C., Rygl, K. L. J., Sanchez, S., Sanchez-Arguelles, D., Savolainen, T., Schloerb, F. P., Schuster, K. -F., Shao, L., Shen, Z., Small, D., Sohn, B. W., Soohoo, J., Sun, H., Tazaki, F., Tetarenko, A. J., Tiede, P., Tilanus, R. P. J., Titus, M., Toma, K., Torne, P., Trent, T., Traianou, E., Trippe, S., Van Bemmel, I., Van Langevelde, H. J., Van Rossum, D. R., Wagner, J., Ward-Thompson, D., Wardle, J., Weintroub, J., Wex, N., Wharton, R., Wielgus, M., Wong, G. N., Wu, Q., Yoon, D., Young, A., Young, K., Younsi, Z., Yuan, F., Yuan, Y. -F., Zensus, J. A., Zhao, G. -Y., Zhao, S. -S., D'Ammando, F., Orienti, M., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. A., Anguner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Barbosa Martins, V., Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlohr, K., Bi, B., Bottcher, M., Boisson, C., Bolmont, J., De Bony De Lavergne, M., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Buchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chen, A., Cotter, G., Curylo, M., Damascene Mbarubucyeye, J., Davids, I. D., Davies, J., Deil, C., Devin, J., Dewilt, P., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., De Clairfontaine, G. F., Fontaine, G., Funk, S., Fussling, 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., Horbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzynski, K., Katz, U., Khangulyan, D., Khelifi, B., Klepser, S., Kluzniak, W., Komin, N., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemiere, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Marti-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., De Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., De Ona Wilhelmi, E., Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. P., Prokhorov, D. A., Prokoph, H., Puhlhofer, G., Punch, M., Quirrenbach, A., Rauth, R., Reichherzer, P., 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., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schutte, 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, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., 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., Volk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Y. W., Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., Zywucka, N., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. A., Artero, M., Asano, K., Baack, D., Babic, A., Baquero, A., De Almeida, U. B., Barrio, J. A., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bosnjak, Z., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Delgado Mendez, C., Depaoli, D., Di Pierro, F., Di Venere, L., Do Souto Espineira, E., Dominis Prester, D., Donini, A., Dorner, D., Doro, M., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Ferrara, G., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Garcia Lopez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinovic, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hutten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jimenez, I., Jormanainen, J., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez-Coto, R., Lopez-Moya, M., Lopez-Oramas, A., Loporchio, S., Machado De Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Menchiari, S., Mender, S., Micanovic, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletic, L., Penil, P., Perennes, C., Persic, M., Moroni, P. G. P., Prandini, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suric, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., Van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Zaric, D., Adams, C. B., Benbow, W., Brill, A., Capasso, M., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Errando, M., Farrell, K. A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Gent, A., Giuri, C., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Jin, W., Kaaret, P., Kertzman, M., Kieda, D., Kumar, S., Lang, M. J., Lundy, M., Maier, G., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Patel, S., Pfrang, K., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Richards, G. T., Roache, E., Rulten, C., Ryan, J. L., Santander, M., Sembroski, G. H., Shang, R., Weinstein, A., Williams, D. A., Williamson, T. J., Hirota, T., Cui, L., Niinuma, K., Ro, H., Sakai, N., Sawada-Satoh, S., Wajima, K., Wang, N., Liu, X., Yonekura, Y., German Research Foundation, Istituto Nazionale di Fisica Nucleare, Swiss National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Department of Atomic Energy (India), University of Tokyo, Japan Society for the Promotion of Science, Ministry of Education and Scientific Research (Romania), Academy of Finland, La Caixa, Croatian Science Foundation, Generalitat de Catalunya, Polish National Agency for Academic Exchange, University of Rijeka, Department of Energy (US), Smithsonian Institution, Astronomy, 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: Accretion, 010504 meteorology & atmospheric sciences, Astronomy, Flux, Astrophysics, 7. Clean energy, 01 natural sciences, Active galactic nuclei, Radio cores, Low-luminosity active galactic nuclei, High energy astrophysics, Astrophysical black holes, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, astro-ph.HE, Radio core, Accretion (meteorology), 520 Astronomie und zugeordnete Wissenschaften, Low-luminosity, active galactic nuclei, Astrophysical black hole, astro-ph.CO, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, High-energy astronomy, astro-ph.GA, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, F500, Astrophysics::Cosmology and Extragalactic Astrophysics, High energy astrophysic, 0103 physical sciences, Very-long-baseline interferometry, ddc:530, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Event Horizon Telescope, Supermassive black hole, Astronomy and Astrophysics, 530 Physik, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), ddc:520, HESS - Abteilung Hinton, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Full list of authors: EHT MWL Science Working Group; Algaba, J. C.; Anczarski, J.; Asada, K.; Baloković, M.; Chandra, S.; Cui, Y. -Z.; Falcone, A. D.; Giroletti, M.; Goddi, C.; Hada, K.; Haggard, D.; Jorstad, S.; Kaur, A.; Kawashima, T.; Keating, G.; Kim, J. -Y.; Kino, M.; Komossa, S.; Kravchenko, E. V.; Krichbaum, T. P.; Lee, S. -S.; Lu, R. -S.; Lucchini, M.; Markoff, S.; Neilsen, J.; Nowak, M. A.; Park, J.; Principe, G.; Ramakrishnan, V.; Reynolds, M. T.; Sasada, M.; Savchenko, S. S.; Williamson, K. E.; Event Horizon Telescope Collaboration; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Anantua, Richard; Azulay, Rebecca; Baczko, Anne-Kathrin; Ball, David; Barrett, John; Bintley, Dan; Benson, Bradford A.; Blackburn, Lindy; Blundell, Raymond; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Boyce, Hope; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chan, Chi-Kwan; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Chesler, Paul M.; Cho, Ilje; Christian, Pierre; Conway, John E.; Cordes, James M.; Crawford, Thomas M.; Crew, Geoffrey B.; Cruz-Osorio, Alejandro; Davelaar, Jordy; de Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Doeleman, Sheperd S.; Eatough, Ralph P.; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Ed; Ford, H. Alyson; Fraga-Encinas, Raquel; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Gold, Roman; Gómez, José L.; Gómez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hecht, Michael H.; Hesper, Ronald; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jiménez-Rosales, Alejandra; Johnson, Michael D.; Jung, Taehyun; Karami, Mansour; Karuppusamy, Ramesh; Kettenis, Mark; Kim, Dong-Jin; Kim, Jongsoo; Kim, Junhan; Koay, Jun Yi; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Michael; Kramer, Carsten; Kuo, Cheng-Yu; Lauer, Tod R.; Levis, Aviad; Li, Yan-Rong; Li, Zhiyuan; Lindqvist, Michael; Lico, Rocco; Lindahl, Greg; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Moran, James M.; Moriyama, Kotaro; Moscibrodzka, Monika; Müller, Cornelia; Musoke, Gibwa; Mejías, Alejandro Mus; Nagai, Hiroshi; Nagar, Neil M.; Nakamura, Masanori; Narayan, Ramesh; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Neri, Roberto; Ni, Chunchong; Noutsos, Aristeidis; Okino, Hiroki; Olivares, Héctor; Ortiz-León, Gisela N.; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C. 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A.; Katarzyński, K.; 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.; Levy, C.; Lohse, T.; Lypova, I.; Mackey, J.; Majumdar, J.; Malyshev, D.; Malyshev, D.; Marandon, V.; Marchegiani, P.; Marcowith, A.; Mares, A.; Martí-Devesa, G.; Marx, R.; Maurin, G.; Meintjes, P. J.; Meyer, M.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Montanari, A.; Moore, C.; Morris, P.; Moulin, E.; Muller, J.; Murach, T.; Nakashima, K.; Nayerhoda, A.; de Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Olivera-Nieto, L.; de Ona Wilhelmi, E.; Ostrowski, M.; Panter, M.; Panny, S.; Parsons, R. D.; Peron, G.; Peyaud, B.; Piel, Q.; Pita, S.; Poireau, V.; Noel, A. Priyana; Prokhorov, D. A.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Rauth, R.; Reichherzer, P.; 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.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Scalici, M.; Schutte, 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.; Sun, L.; Steenkamp, R.; Stegmann, C.; Steinmassl, S.; Steppa, C.; Takahashi, T.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tiziani, D.; Tluczykont, M.; Tomankova, L.; Trichard, C.; Tsirou, M.; 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.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Watson, J.; Werner, F.; White, R.; Wierzcholska, A.; Wong, Yu Wun; Yusafzai, A.; Zacharias, M.; Zanin, R.; Zargaryan, D.; Zdziarski, A. A.; Zech, A.; Zhu, S. J.; Zorn, J.; Zouari, S.; Żywucka, N.; MAGIC Collaboration; Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Engels, A. Arbet; Artero, M.; Asano, K.; Baack, D.; Babić, A.; Baquero, A.; de Almeida, U. Barres; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G.; Bošnjak, Ž.; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colak, S. M.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; da Vela, P.; Dazzi, F.; de Angelis, A.; de Lotto, B.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Depaoli, D.; di Pierro, F.; di Venere, L.; Do Souto Espiñeira, E.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Ramazani, V. Fallah; Fattorini, A.; Ferrara, G.; Fonseca, M. V.; Font, L.; Fruck, C.; Fukami, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinović, N.; Green, J. G.; Green, D.; Hadasch, D.; Hahn, A.; Heckmann, L.; Herrera, J.; Hoang, J.; Hrupec, D.; Hütten, M.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jiménez, I.; Jormanainen, J.; Jouvin, L.; Kajiwara, Y.; Karjalainen, M.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menchiari, S.; Mender, S.; Mićanović, S.; Miceli, D.; Miener, T.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Neustroev, V.; Nigro, C.; Nilsson, K.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletić, L.; Peñil, P.; Perennes, C.; Persic, M.; Moroni, P. G. Prada; Prandini, E.; Priyadarshi, C.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Saturni, F. G.; Schleicher, B.; Schmidt, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suda, Y.; Surić, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Tosti, L.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Ventura, S.; Verguilov, V.; Vigorito, C. F.; Vitale, V.; Vovk, I.; Will, M.; Wunderlich, C.; Zarić, D.; VERITAS Collaboration; Adams, C. B.; Benbow, W.; Brill, A.; Capasso, M.; Christiansen, J. L.; Chromey, A. J.; Daniel, M. K.; Errando, M.; Farrell, K. A.; Feng, Q.; Finley, J. P.; Fortson, L.; Furniss, A.; Gent, A.; Giuri, C.; Hassan, T.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Jin, W.; Kaaret, P.; Kertzman, M.; Kieda, D.; Kumar, S.; Lang, M. J.; Lundy, M.; Maier, G.; Moriarty, P.; Mukherjee, R.; Nieto, D.; Nievas-Rosillo, M.; O'Brien, S.; Ong, R. A.; Otte, A. N.; Patel, S.; Pfrang, K.; Pohl, M.; Prado, R. R.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Ribeiro, D.; Richards, G. T.; Roache, E.; Rulten, C.; Ryan, J. L.; Santander, M.; Sembroski, G. H.; Shang, R.; Weinstein, A.; Williams, D. A.; Williamson, T. J.; Eavn Collaboration; Hirota, Tomoya; Cui, Lang; Niinuma, Kotaro; Ro, Hyunwook; Sakai, Nobuyuki; Sawada-Satoh, Satoko; Wajima, Kiyoaki; Wang, Na; Liu, Xiang; Yonekura, Yoshinori, In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded., The financial support of the German BMBF, MPG and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovacion (MICINN) (FPA2017-87859-P, FPA2017-85668-P, FPA2017- 82729-C6-5-R, FPA2017-90566-REDC, PID2019-104114RBC31, PID2019-104114RB-C32, PID2019-105510GB-C31,PID 2019-107847RB-C41, PID2019-107847RB-C42, PID2019- 107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant No. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588 and CEX2019- 000920-S, and “Maria de Maeztu” CEX2019-000918-M, the Unidad de Excelencia “Maria de Maeztu” MDM-2015-0509- 18-2 and the “la Caixa” Foundation (fellowship LCF/BQ/ PI18/11630012) and by the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; the Polish National Research Centre grant UMO-2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq, and FAPERJ. This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation and the Smithsonian Institution, by NSERC in Canada, and by the Helmholtz Association in Germany. This research used resources provided by the Open Science Grid, which is supported by the National Science Foundation and the U.S. Department of Energy’s Office of Science, and resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the instrument.
Published: 2021

19. Analysis of the Physical Workload and Ergonomic Design of Workstations for 'Goods-to-Person' Order Picking

Author: Verena Klaer, Gernot Maier, Jurij Wakula, Willibald Rabenhaupt, and Tim Steinebach
Subjects: Order picking, Fully automated, Workstation, law, Human–computer interaction, Computer science, Work (physics), Repetitive movements, Human factors and ergonomics, Workload, Motion capture, law.invention
Abstract: Goods-to-person picking is a dynamic, semi-automated or fully automated picking method. The main physical workloads are caused by standing work postures and repetitive movements of the upper extremities.
Published: 2021

20. Demonstration of stellar intensity interferometry with the four VERITAS telescopes

Author: T. T.Y. Lin, K. Ragan, J. H. Buckley, A. Brill, Gernot Maier, S. P. Wakely, D. S. Hanna, Q. Feng, Nolan Matthews, A. J. Chromey, A. Weinstein, Lucy Fortson, R. A. Ong, Jonathan Davis, F. Krennrich, Tugdual LeBohec, T. J. Williamson, Anushka Udara Abeysekara, Olivier Hervet, Orel Gueta, P. Wilcox, S. O'Brien, S. Kumar, M. Lundy, J. P. Finley, Amy Furniss, M. K. Daniel, Reshmi Mukherjee, Gordon T. Richards, T. B. Humensky, C. Giuri, E. Pueschel, Martin Pohl, G. H. Sembroski, P. Kaaret, A. D. Falcone, P. Moriarty, M. Nievas-Rosillo, Jodi Christiansen, David Kieda, A. N. Otte, K. Pfrang, M. Kertzman, Jamie Holder, Marcos Santander, P. T. Reynolds, Alasdair E. Gent, R. R. Prado, David A. Williams, Wystan Benbow, G. Hughes, E. Roache, Tarek M. Hassan, John L. Quinn, D. Ribeiro, and James Ryan
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Telescope, Angular diameter, law, 0103 physical sciences, Astronomical interferometer, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Cherenkov radiation, Astrophysics::Galaxy Astrophysics, Physics, Stellar atmosphere, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Cherenkov Telescope Array, Interferometry, Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: High angular resolution observations at optical wavelengths provide valuable insights in stellar astrophysics, directly measuring fundamental stellar parameters, and probing stellar atmospheres, circumstellar disks, elongation of rapidly rotating stars, and pulsations of Cepheid variable stars. The angular size of most stars are of order one milli-arcsecond or less, and to spatially resolve stellar disks and features at this scale requires an optical interferometer using an array of telescopes with baselines on the order of hundreds of meters. We report on the successful implementation of a stellar intensity interferometry system developed for the four VERITAS imaging atmospheric-Cherenkov telescopes. The system was used to measure the angular diameter of the two sub-mas stars $\beta$ Canis Majoris and $\epsilon$ Orionis with a precision better than 5%. The system utilizes an off-line approach where starlight intensity fluctuations recorded at each telescope are correlated post-observation. The technique can be readily scaled onto tens to hundreds of telescopes, providing a capability that has proven technically challenging to current generation optical amplitude interferometry observatories. This work demonstrates the feasibility of performing astrophysical measurements with imaging atmospheric-Cherenkov telescope arrays as intensity interferometers and the promise for integrating an intensity interferometry system within future observatories such as the Cherenkov Telescope Array., Comment: Accepted for publication in Nature Astronomy (2020)
Published: 2020

21. Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations

Author: P. Kaaret, R. Mukherjee, M. Nievas-Rosillo, N. Kelley-Hoskins, C. Giuri, Gernot Maier, E. Roache, Ralph Bird, David Kieda, R. A. Ong, Kaya Mori, K. Ragan, D. S. Hanna, Orel Gueta, Abraham D. Falcone, A. Brill, P. Wilcox, C. J. Hailey, Tarek M. Hassan, M. Kertzman, David A. Williams, A. N. Otte, Amy Furniss, G. H. Sembroski, A. Weinstein, Marcos Santander, A. J. Chromey, I. Sadeh, Robert Brose, Maria Krause, N. H. Park, I. Sushch, Wystan Benbow, J. P. Finley, T. J. Williamson, Jodi Christiansen, O. Hervet, A. Archer, A. Petrashyk, Jamie Holder, P. T. Reynolds, E. Pueschel, M. J. Lang, S. O'Brien, A. Gent, G. H. Gillanders, Q. Feng, Lucy Fortson, Shifra Mandel, D. Ribeiro, Gordon T. Richards, John L. Quinn, A. Wilhelm, Weiguang Cui, K. Pfrang, Daniel Nieto, G. Hughes, Martin Pohl, T. B. Humensky, S. Schlenstedt, P. Moriarty, M. Buchovecky, and R.R. Prado
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, 010504 meteorology & atmospheric sciences, Be star, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Spectral density, Astronomy and Astrophysics, Electron, Astrophysics, Compact star, Light curve, 01 natural sciences, Pulsar, 13. Climate action, Space and Planetary Science, 0103 physical sciences, ddc:520, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: HESS J0632+057 is a gamma-ray binary composed of a compact object orbiting a Be star with a period of about $315$ days. Extensive X-ray and TeV gamma-ray observations have revealed a peculiar light curve containing two peaks, separated by a dip. We present the results of simultaneous observations in hard X-rays with NuSTAR and in TeV gamma-rays with VERITAS, performed in November and December 2017. These observations correspond to the orbital phases $\phi\approx0.22$ and $0.3$, where the fluxes are rising towards the first light-curve peak. A significant variation of the spectral index from 1.77$\pm$0.05 to 1.56$\pm$0.05 is observed in the X-ray data. The multi-wavelength spectral energy distributions (SED) derived from the observations are interpreted in terms of a leptonic model, in which the compact object is assumed to be a pulsar and non-thermal radiation is emitted by high-energy electrons accelerated at the shock formed by the collision between the stellar and pulsar wind. The results of the SED fitting show that our data can be consistently described within this scenario, and allow us to estimate the magnetization of the pulsar wind at the location of the shock formation. The constraints on the pulsar-wind magnetization provided by our results are shown to be consistent with those obtained from other systems., Comment: Accepted for publication in The Astrophysical Journal
Published: 2020
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22. VERITAS Detection of LS 5039 and HESS J1825-137

Author: Olivier Hervet, Dirk Pandel, Marita Krause, John L. Quinn, G. Hughes, P. T. Reynolds, Ralph Bird, Tarek M. Hassan, David Kieda, Jodi Christiansen, P. Wilcox, D. S. Hanna, K. Ragan, Wystan Benbow, I. Sadeh, A. Weinstein, M. Pohl, Anushka Udara Abeysekara, Marcos Santander, R. A. Ong, M. J. Lang, A. D. Falcone, Wei Cui, Jamie Holder, M. Kertzman, T. B. Humensky, Robert Brose, M. K. Daniel, R. R. Prado, N. Kelley-Hoskins, P. Kar, David A. Williams, Lucy Fortson, P. Kaaret, M. Nievas-Rosillo, T. J. Williamson, G. H. Sembroski, E. Pueschel, Gernot Maier, P. Moriarty, A. J. Chromey, Gordon T. Richards, E. Roache, Daniel Nieto, U.S. Department of Energy Office of Science, National Science Foundation, Smithsonian Institution, and Natural Sciences and Engineering Research Council of Canada
Subjects: individual objects, stars, Open science, HESS J1825-137, Smithsonian institution, VHE [gamma ray], FOS: Physical sciences, Library science, 01 natural sciences, Technical support, star, HESS, 0103 physical sciences, User Facility, close, individual, 010303 astronomy & astrophysics, ISM, pulsar, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, gamma rays, flux, inverse scattering method, Work (electrical), binary [gamma ray], general, ddc:540, LS 5039, VERITAS, Astrophysics - High Energy Astrophysical Phenomena, binaries, statistical
Abstract: With 8 hours of observations, VERITAS confirms the detection of two very high energy gamma-ray sources. The gamma-ray binary LS 5039 is detected with a statistical significance of $8.8\sigma$. The measured flux above 1 TeV is $(2.5 \pm 0.4) \times 10^{-12} \rm \, cm^{-2} \, s^{-1}$ near inferior conjunction and $(7.8 \pm 2.8) \times 10^{-13} \rm \, cm^{-2} \, s^{-1}$ near superior conjunction. The pulsar wind nebula HESS J1825-137 is detected with a statistical significance of $6.7\sigma$ and a measured flux above 1 TeV of $(3.9 \pm 0.8) \times 10^{-12} \rm \, cm^{-2} \, s^{-1}$., Comment: 4 pages, 2 figures
Published: 2020

23. VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study

Author: A. Brill, Alasdair E. Gent, James Ryan, Manel Errando, E. T. Meyer, Gordon T. Richards, Olivier Hervet, M. Kertzman, E. Roache, A. Archer, T. T.Y. Lin, K. Ragan, R. A. Ong, S. O'Brien, B. Stevenson, D. S. Hanna, G. Hughes, Wystan Benbow, P. Moriarty, Matthew L. Lister, C. B. Rulten, M. Lundy, K. Ramirez, Karlen Shahinyan, T. J. Williamson, Tarek M. Hassan, A. Wilhelm, David Kieda, Daniel Nieto, M. Nievas-Rosillo, A. C. Sadun, Jodi Christiansen, Jamie Holder, Marcos Santander, P. T. Reynolds, K. Pfrang, John L. Quinn, D. Ribeiro, R. Shang, M. J. Lang, Gernot Maier, A. D. Falcone, A. Weinstein, M. Pohl, S. P. Wakely, R. R. Prado, M. K. Daniel, P. Fortin, Ralph Bird, David A. Williams, Orel Gueta, P. Wilcox, J. H. Buckley, S. S. Scott, A. J. Chromey, Michael T. Carini, F. Krennrich, M. Georganopoulos, Reshmi Mukherjee, C. Giuri, Q. Feng, G. H. Gillanders, T. B. Humensky, P. Kaaret, Lucy Fortson, M. Buchovecky, G. H. Sembroski, E. Pueschel, Vladimir Vassiliev, and Amy Furniss
Subjects: 010504 meteorology & atmospheric sciences, Radio galaxy, atmosphere [Cherenkov counter], Astrophysics, cosmic background radiation, power spectrum, 01 natural sciences, law.invention, Astrophysical jet, law, pixel, ultraviolet, black hole, optical, dimension: 2, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), photon, 2 [dimension], Elliptical galaxy, Spectral energy distribution, VERITAS, Astrophysics - High Energy Astrophysical Phenomena, Lorentz, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, radio wave [galaxy], energy spectrum, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Cherenkov counter: atmosphere, VHE, GLAST, Telescope, X-ray, 0103 physical sciences, structure, Very Long Baseline Array, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, polarization, synchrotron radiation, background, galaxy: radio wave, Astronomy and Astrophysics, Doppler effect, flux, Crab Nebula, Space and Planetary Science, gamma ray, ddc:520, spectral, statistical
Abstract: The astrophysical journal 896(1), 41 - (2020). doi:10.3847/1538-4357/ab910e, The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E $>100$ GeV) $\gamma$-ray emission from this active galaxy. An analysis of $\sim$57 hours of quality-selected live time yields a detection at the position of the source, corresponding to a statistical significance of 7.8 standard deviations above background. The observed VHE flux is variable on monthly time scales, with an elevated flux seen in 2018 observations. The VHE emission during this elevated state is well-characterized by a power-law spectrum with a photon index $\Gamma = 2.20 \pm 0.27$ and flux F($>315$ GeV) = ($7.6\pm 1.2_{\mathrm stat} \pm 2.3_{\mathrm syst})\times 10^{-13}$ cm$^{-2}$ s$^{-1}$, or approximately 0.7% of the Crab Nebula flux above the same threshold. 3C 264 ($z = 0.0217$) is the most distant radio galaxy detected at VHE, and the elevated state is thought to be similar to that of the famously outbursting jet in M 87. Consequently, extensive contemporaneous multi-wavelength data were acquired in 2018 at the time of the VHE high state. An analysis of these data, including VLBA, VLA, HST, Chandra and Swift observations in addition to the VERITAS data, is presented, along with a discussion of the resulting spectral energy distribution., Published by Univ.8743, Chicago, Ill. [u.a.]
Published: 2020
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24. Computational Modelling of Thermal Runaway Propagation in Lithium-Ion Battery Systems

Author: Gernot Maier, Bernhard Brunnsteiner, Jürgen Schneider, Martina Citarella, Daniele Suzzi, and Paul Schiffbänker
Subjects: Flammable liquid, Ignition system, chemistry.chemical_compound, Computer simulation, Thermal runaway, chemistry, law, Nuclear engineering, Environmental science, Battery pack, Lithium-ion battery, law.invention
Abstract: Different abuse conditions in Lithium-Ion batteries may lead to the so-called Thermal Runaway (TR) which releases the cell energy and the highly flammable and toxic venting gas. The propagation to the neighboring cells and modules may lead to fire and explosions. Hence, the propagation prevention is fundamental to meet safety requirements for electric vehicles.During battery pack development at AVL, this phenomenon is modelled applying CAE methods, allowing evaluation of design countermeasures: One cell is artificially triggered and the propagation to the other cells is evaluated, together with the ignition probability of the venting gas based on measured species concentration.
Published: 2019

25. An Archival Search for Neutron-star Mergers in Gravitational Waves and Very-high-energy Gamma Rays

Author: M. Lundy, Lucy Fortson, Reshmi Mukherjee, M. K. Daniel, A. Weinstein, C. Giuri, P. Kaaret, David Kieda, Olivier Hervet, C. E. McGrath, S. Márka, Wystan Benbow, Martin Pohl, A. D. Falcone, Alasdair E. Gent, P. Moriarty, R. A. Ong, James Ryan, S. Kumar, J. H. Buckley, R. R. Prado, P. T. Reynolds, M. Kertzman, Amy Furniss, M. Nievas-Rosillo, Nahee Park, A. J. Chromey, Doğa Veske, G. H. Sembroski, M. Capasso, Q. Feng, E. Pueschel, Imre Bartos, Jodi Christiansen, A. Brill, Daniel Nieto, David A. Williams, Marcos Santander, A. N. Otte, K. Pfrang, C. B. Adams, D. S. Hanna, G. Hughes, J. P. Finley, Jamie Holder, K. R. Corley, K. Ragan, R. Shang, T. J. Williamson, Z. Márka, S. O'Brien, E. Roache, K. A. Farrell, Tarek M. Hassan, John L. Quinn, D. Ribeiro, W. Jin, M. J. Lang, Manel Errando, S. Patel, T. B. Humensky, and Gernot Maier
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, IACT, Gamma-ray astronomy, Cherenkov Telescope Array, 030226 pharmacology & pharmacy, 01 natural sciences, LIGO, 03 medical and health sciences, Neutron star, 0302 clinical medicine, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Gamma-ray burst, 010303 astronomy & astrophysics, Cherenkov radiation
Abstract: The recent discovery of electromagnetic signals in coincidence with neutron-star mergers has solidified the importance of multimessenger campaigns in studying the most energetic astrophysical events. Pioneering multimessenger observatories, such as LIGO/Virgo and IceCube, record many candidate signals below the detection significance threshold. These sub-threshold event candidates are promising targets for multimessenger studies, as the information provided by them may, when combined with contemporaneous gamma-ray observations, lead to significant detections. Here we describe a new method that uses such candidates to search for transient events using archival very-high-energy gamma-ray data from imaging atmospheric Cherenkov telescopes (IACTs). We demonstrate the application of this method to sub-threshold binary neutron star (BNS) merger candidates identified in Advanced LIGO's first observing run. We identify eight hours of archival VERITAS observations coincident with seven BNS merger candidates and search them for TeV emission. No gamma-ray emission is detected; we calculate upper limits on the integral flux and compare them to a short gamma-ray burst model. We anticipate this search method to serve as a starting point for IACT searches with future LIGO/Virgo data releases as well as in other sub-threshold studies for multimessenger transients, such as IceCube neutrinos. Furthermore, it can be deployed immediately with other current-generation IACTs, and has the potential for real-time use that places minimal burden on experimental operations. Lastly, this method may serve as a pilot for studies with the Cherenkov Telescope Array, which has the potential to observe even larger fields of view in its divergent pointing mode.
Published: 2021

26. Influence of uncertainty in hadronic interaction models on the sensitivity estimation of Cherenkov Telescope Array

Author: Luisa Arrabito, Luan B. Arbeletche, Gernot Maier, T. Yoshikoshil, Johan Bregeon, Konrad Bernlöhr, Abelardo Moralejo, V. de Souza, Michiko Ohishi, 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), and CTA Consortium
Subjects: History, Cherenkov Telescope Array, interaction: model, current: hadronic, air, Astrophysics::High Energy Astrophysical Phenomena, Hadron, feedback, Cherenkov counter: atmosphere, 01 natural sciences, Education, Optics, 0103 physical sciences, gamma ray: detector, Sensitivity (control systems), 010303 astronomy & astrophysics, Physics, showers: atmosphere, 010308 nuclear & particles physics, business.industry, p: background, nucleus, Astrophysics::Instrumentation and Methods for Astrophysics, imaging, sensitivity, Computer Science Applications, gamma ray: VHE, 13. Climate action, p: cosmic radiation, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Very-high-energy (VHE) interaction between cosmic-ray proton and nuclei in the atmosphere is still not perfectly understood and efforts to improve interaction models used in simulations are ongoing, with feedback from various collider and air shower experiments. Imaging Atmospheric Cherenkov Telescopes (IACTs) are indirect VHE gamma-ray detectors on the ground and cosmic-ray proton is a major background to gamma-ray measurements in these systems. Rejection power of background protons determines most part of the gamma-ray sensitivity curve of IACTs. As for an IACT system in design phase, simulated proton events are used to estimate the residual background level. We investigated the influence of the uncertainty in the current hadronic interaction models on the estimated gamma-ray sensitivity of Cherenkov Telescope Array, using several interaction models available in CORSIKA.
Published: 2019

27. Multiwavelength observation of MAXI J1820+070 with MAGIC, VERITAS and H.E.S.S

Author: E. Molina, M. de Naurois, Oscar Blanch, S. Ohm, N. Park, D. Malyshev, Gernot Maier, Alison Mitchell, M. Lopez, E. de Oña Wilhelmi, Roberta Zanin, John Hoang, Jean-Pierre Ernenwein, Juan Cortina, Marc Ribó, 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 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), MAGIC, VERITAS, H.E.S.S., 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)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), and MAGIC, VERITAS
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), High energy, media_common.quotation_subject, Magic (programming), FOS: Physical sciences, Astrophysics, sensitivity, MAGIC, X-ray, gamma ray: emission, gamma ray: VHE, Sky, pixel, HESS, optical, black hole, gamma ray: detector, VERITAS, quasar, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], media_common
Abstract: 36th International Cosmic Ray Conference (ICRC2019), Madison, USA, 24 Jul 2019 - 1 Aug 2019, MAXI J1820+070 is a new low-mass microquasar hosting a black hole recently discovered in X-rays by the MAXI instrument. It is the counterpart of ASASSN-18ey, discovered in optical a few days before by ASAS-SN. This source underwent a major outburst in 2018, during which it completed the typical 'q-shaped' path in the hardness-intensity diagram. MAGIC, VERITAS and H.E.S.S. gamma-ray telescopes observed the sky position of MAXI J1820+070 for a total of more than 90 hours in 2018. In addition, some observations were carried out using MAGIC Central Pixel - a dedicated central pixel capable of detecting fast optical signals (10 kHz sampling rate, peak sensitivity in the U-band). This contribution presents the methods used to search for transient optical and very high energy gamma-ray emission from MAXI J1820+070, as well as the latest results in these energy ranges.
Published: 2019
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28. Long-term gamma-ray observations of the binary HESS J0632+057 with H.E.S.S., MAGIC and VERITAS

Author: Denys Malyshev, Gerd Pühlhofer, Stefan Ohm, Raul Prado, Johannah Moepi, Oscar Blanch, Gernot Maier, Diego F. Torres, M. Lundy, Nukri Komin, Daniela Hadasch, Ben Zitzer, Stefan Schlenstedt, and A. López-Oramas
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, FOS: Physical sciences, Context (language use), Astrophysics, Light curve, Orbital period, law.invention, Telescope, law, Observatory, Astrophysics::Solar and Stellar Astrophysics, MAGIC (telescope), Astrophysics - High Energy Astrophysical Phenomena, Cherenkov radiation
Abstract: The gamma-ray binary HESS J0632+057 has been observed at very-high energies (E $>$ 100 GeV) for more than ten years by the major systems of imaging atmospheric Cherenkov telescopes. We present a summary of results obtained with the H.E.S.S., MAGIC, and VERITAS experiments based on roughly 440 h of observations in total. This includes a discussion of an unusually bright TeV outburst of HESS J0632+057 in January 2018. The updated gamma-ray light curve now covers all phases of the orbital period with significant detections in almost all orbital phases. Results are discussed in context with simultaneous observations with the X-ray Telescope onboard the Neil Gehrels Swift Observatory., Proceedings of the 36th International Cosmic Ray Conference (ICRC2019) Madison, WI July 24-Aug 1, 2019
Published: 2019

29. Appendix: Simulating CTA

Author: Gernot Maier
Subjects: medicine.anatomical_structure, Physics::Instrumentation and Detectors, Computer science, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, medicine, Nuclear medicine, business, ddc:522.6862, Appendix
Abstract: The expectations for the scientific capabilities of CTA presented in this document are based on sensitivity and response functions derived from detailed Monte Carlo simulations of the CTA observatory. The simulations model extensive air showers initiated by high-energy (HE) primary particles (gamma rays or background cosmic-ray nuclei and electrons), the Cherenkov light production by the shower particles, and the measurement processes of imaging atmospheric Cherenkov telescopes…
Published: 2019

30. The Cherenkov Telescope Array sensitivity to the transient sky

Author: Abelardo Moralejo, Gernot Maier, Andrea Bulgarelli, Thomas Brian Humensky, Valentina Fioretti, C. Nigro, and D. Ribeiro
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Active galactic nucleus, business.industry, Gravitational wave, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Cherenkov Telescope Array, Photometry (optics), Optics, Sky, Neutrino, business, Gamma-ray burst, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common
Abstract: The Cherenkov Telescope Array (CTA) will be able to perform unprecedented observations of the transient very high-energy sky. An on-line science alert generation (SAG) pipeline, with a required 30 second latency, will allow the discovery or follow-up of gamma ray bursts (GRBs) and flaring emission from active galactic nuclei, galactic compact objects and electromagnetic counterparts of gravitational waves or neutrino messengers. The CTA sensitivity for very short exposures does not only depend on the technological performance of the array (e.g. effective area, background discrimination efficiency). The algorithms to evaluate the significance of the detection also define the sensitivity, together with their computational efficiency in order to satisfy the SAG latency requirements. We explore the aperture photometry and likelihood analysis techniques, and the associated parameters (e.g. on-source to off-source exposure ratio, minimum number of required signal events), defining the CTA ability to detect a significant signal at short exposures. The resulting CTA differential flux sensitivity as a function of the observing time, obtained using the latest Monte Carlo simulations, is compared to the sensitivities of Fermi-LAT and current-generation IACTs obtained in the overlapping energy ranges., Comment: Proceedings of the 36th International Cosmic Ray Conference - Madison, WI, USA (PoS(ICRC2019)673)
Published: 2019
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31. Direct measurement of stellar angular diameters by the VERITAS Cherenkov telescopes

Author: M. J. Lang, Robert Brose, S. O'Brien, J. P. Finley, Gernot Maier, Nahee Park, T. J. Williamson, M. K. Daniel, Daniel Nieto, Jamie Holder, Wystan Benbow, A. M. Joyce, S. P. Wakely, John L. Quinn, Nolan Matthews, Cameron B Rulten, A. Petrashyk, D. S. Hanna, A. Furniss, T. B. Humensky, P. Kar, I. Sushch, R. M. Wells, P. Wilcox, P. Kaaret, N. Kelley-Hoskins, E. Roache, E. Pueschel, Ralph Bird, Martin Pohl, M. Kertzman, David Kieda, David A. Williams, Karlen Shahinyan, Tarek M. Hassan, I. Sadeh, R. A. Ong, C. Giuri, A. Brill, K. Ragan, Q. Feng, Gordon T. Richards, Maria Krause, Marcos Santander, M. Nievas-Rosillo, P. T. Reynolds, R. Mukherjee, T. T.Y. Lin, A. Wilhelm, P. Moriarty, Lucy Fortson, G. Hughes, G. H. Gillanders, Orel Gueta, A. J. Chromey, G. H. Sembroski, and Jules P. Halpern
Subjects: Brightness, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Occultation, law.invention, Telescope, Photometry (optics), Angular diameter, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, ddc:530, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Cherenkov radiation, 0105 earth and related environmental sciences, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Institut für Physik und Astronomie, Astronomy and Astrophysics, Stars, Astrophysics - Solar and Stellar Astrophysics, ddc:520, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Nature astronomy 3(6), 511 - 516 (2019). doi:10.1038/s41550-019-0741-z, The angular size of a star is a critical factor in determining its basic properties$^1$. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star$^2$, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation$^3$. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements$^4$. Here we report two occultations of stars observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS)$^5$ Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars’ angular diameter at the ≤0.1 mas scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method$^6$. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications., Published by Nature Publishing Group, London
Published: 2019
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32. The Cherenkov Telescope Array Performance in Divergent Mode

Author: Abelardo Moralejo, Federico Di Pierro, Gernot Maier, Thomas Vuillaume, Francesco Longo, Alice Donini, Thomas Gasparetto, Johan Bregeon, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), 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 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), CTA Consortium, Laboratoire d'Annecy de Physique des Particules (LAPP), SISSA, Donini, A., Gasparetto, T., Bregeon, J., Di Pierro, F., Longo, F., Maier, G., Moralejo, A., and Vuillaume, T.
Subjects: Offset (computer science), Cherenkov Telescope Array, Performance estimation, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, measurement methods, FOS: Physical sciences, Field of view, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, VHE, law.invention, Telescope, law, Extended field of view, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, media_common, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, astro-ph.IM, Sky, Astrophysics - Instrumentation and Methods for Astrophysics, numerical calculations: Monte Carlo, performance
Abstract: Two of the Key Science Projects of the Cherenkov Telescope Array (CTA) consist in performing a deep survey of the Galactic and Extragalactic sky, providing an unbiased view of the Universe at energies above tens of GeV. To optimize the time spent to perform the Extragalactic survey, a so-called "divergent mode" of the CTA was proposed as an alternative observation strategy to the traditional parallel pointing in order to increase its instantaneous field of view. The search for transient VHE sources would also benefit from an extended field of view. In the divergent mode, each telescope points to a position in the sky that is slightly offset, in the outward direction, from the center of the field of view. In this contribution, we present the first performance estimation from full Monte Carlo simulation of possible CTA divergent mode setups., Comment: 8 pages with 10 figures, submitted to ICRC
Published: 2019
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33. Combined Dark Matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, HESS, MAGIC and VERITAS

Author: Dirk Lennarz, Luis Villaseñor, Gernot Maier, Anne Lemiere, Daniel Rosa-Gonzalez, Samuel Timothy Spencer, Wystan Benbow, Victor Barbosa Martins, Raul Prado, Arache Djannati-Ataï, Regis Terrier, Dan Parsons, Francisco Salesa Greus, Dmitriy Kostunin, Joshua Wood, Carlo Romoli, César Alvarez, Carlo van Rensburg, Massimo Capasso, Sajan Kumar, P. Reichherzer, Anton Dmytriiev, Stefan Ohm, Chiara Giuri, Brian van Soelen, G. Peron, Christian Stegmann, Emma Ona-Wilhelmi, S. J. Fegan, Alison Peisker, Hawc, Garret Cotter, Gary Gillanders, Zhiqiu Huang, Krzysztof Katarzynski, Filiberto Hueyotl-Zahuantitla, Ian Herzog, D. A. Prokhorov, K. Kosack, Halim Ashkar, Fabian Leuschner, Manami Sasaki, Michael Schneider, Joe Lundeen, Markus Boettcher, Brian Humensky, Isak Delberth Davids, A. Fiasson, Stefan Wagner, Andreas Zech, Yasunobu Uchiyama, David Kieda, Michael DuVernois, Albert Seyffert, Gianluca Giavitto, Qi Feng, Andreas Specovius, Andrew James Smith, Catherine Boisson, L. Mohrmann, Roberta Zanin, Marek Jamrozy, Tomás Capistrán Rojas, K. Nakashima, Jamie Holder, Hao Zhou, Thomas Lohse, Mireia Nievas-Rosillo, Samuel Zouari, Ira Jung, Sebastian Panny, K. Bernloehr, Deivid Ribeiro, Andrea Santangelo, Kristi Engel, Josefa Becerra Gonzalez, Thomas Tavernier, Ke Fang, Rishi Babu, Yu Wun Wong, Gerd J. Kunde, Jean-Pierre Ernenwein, Henrike Fleischhack, P. T. O'Brien, Clemens Hoischen, A. A. Zdziarski, Kelly Malone, Helene Sol, Markus Holler, Manel Errando, Atreyee Sinha, Francois Brun, Heinrich J. Völk, Sumari Hattingh, Kirsten Tollefson, Johann van der Walt, Q. Remy, Felix Jankowsky, Samridha Kunwar, Johannes Veh, M. Fuessling, P. Vincent, Harm Schoorlemmer, Stefano Gabici, Miguel Mostafa, Tyler Williamson, Jacek Niemiec, Michal Ostrowski, J.-P. Lenain, Israel Martinez Castellanos, Felix Aharonian, Tadayuki Takahashi, Gerd Puehlhofer, Lei Sun, Jesús Martínez-Castro, Pooja Surajbali, Andrés Sandoval, Hugh Spackman, Takaaki Tanaka, Segev BenZvi, Alexandre Marcowith, Felix Werner, Olaf Reimer, Vincent Marandon, Alberto Carramiñana, S. Steinmassl, Mary Kertzman, Hannes Thiersen, Victor Doroshenko, Michael Backes, Hannah Jhee, G. Lamanna, Marcos Santander, Angel Noel, W. Jin, Gus Sinnis, B. Rudak, Alasdair E. Gent, Kathrin Egberts, Jonathan Mackey, Fernando Ureña-Mena, Paolo Marchegiani, Sonal Ramesh Patel, Laenita Lorraine Oberholzer, Tim Holch, Sami Caroff, Heiko Salzmann, E. Kasai, Alison Mitchell, Gregory Foote, Nukri Komin, Tom Armstrong, Michelle Hui, Ruo-Yu Shang, Binita Hona, Raquel Diaz Hernandez, Vardan Baghmanyan, Celine Armand, Alejandro Lara, David Berley, Hector Rueda Ricarte, Nissim Illich Fraija, Naomi Tsuji, Gaurang Yodh, Stefan Funk, Alicja Wierzcholska, Conor McGrath, Gerard Fontaine, C. Moore, Vikas Joshi, Dorit Glawion, T. Chand, M. U. Nisa, M.-H. Grondin, Arnaud Mares, David Sanchez, Ernesto Belmont-Moreno, Thomas Murach, Eucario Gonzalo Pérez Pérez, Paul Reynolds, Ignacio Taboada, Xiaojie Wang, Lucy Fortson, Martin Tluczykont, Thomas Brian Humensky, Juan de Dios Álvarez Romero, Robert Ellsworth, Hester Schutte, Justine Devin, Constantin Steppa, Richard White, Rachel Simoni, Karen S. Caballero Mora, Elisa Pueschel, Jason Fan, Tomasz Bulik, Lukas Nellen, Malgorzata Curlo, Lente Dreyer, J. Patrick Harding, Gilles Maurin, Humberto Martínez Huerta, Riaan Steenkamp, Arnulfo Zepeda, Johannes Schaefer, Werner Hofmann, Jim Hinton, Michael Punch, S. Sailer, Dmitry Khangulyan, Sergio Hernández Cadena, Charles Thorpe-Morgan, M. Hörbe, Stephan O'Brien, Ramin Marx, John L. Quinn, J. F. Glicenstein, V. Sahakian, M. Panter, Mora Durocher, U. Katz, Jacco Vink, Umberto Cotti, Tobias Kleiner, Petra Hüntemeyer, David Huber, Ullrich Schwanke, Diego Garcia Aguilar, Vladimir Vassiliev, Oscar Martinez, J. Bolmont, Cederik León de León, Brian Fick, Laura Olivera-Nieto, A. Yusafzai, David Hanna, James Buckley, Lorenzo Diaz, Yves Gallant, Guillermo García-Torales, Arun Babu Kollamparambil, James Ryan, Kayla Farrell, Sabrina Casanova, Bruno Khelifi, María Catalina Espinoza Hernández, Jorge Antonio Morales Soto, Mateo Fernandez Alonso, Matthew Lundy, Faical Ait-Benkhali, Jean Damascene Mbarubucyeye, Wlodek Kluzniak, Jorge Luis Flores, Ibrahim Torres, Jordan A. Goodman, Anita Reimer, Adam Otte, Eduardo Moreno Barbosa, M. J. Lang, Frank M. Rieger, Elijah Willox, Colin Adams, Pedro Miranda-Romagnoli, Louis Du Plessis, Andrea Albert, Orel Gueta, Anna Barnacka, Brenda Dingus, Gašper Kukec Mezek, Hazal Goksu, Jorge Cotzomi, William H. Lee, Ruben Alfaro, Glenn Sembroski, David A. Williams, Eduardo de la Fuente, Anu Kundu, Dezhi Huang, Brian Reville, Connor Duffy, Edna Ruiz-Velasco, Anna Luashvili, Alisha Chromey, Konstantin Pfrang, L. Giunti, Philip Kaaret, Maria Magdalena González, Olivier Hervet, Hermes Leon Vargas, Sébastien Le Stum, Amanda Weinstein, Aryeh Brill, James Davies, Ken Ragan, Santiago Pita, Juan Carlos Arteaga Velazquez, Jason Lee, Sabrina Einecke, Lukasz Stawarz, Iryna Lypova, Julie McEnery, Sara Coutiño de Leon, Dieter Horns, R. J. Tuffs, Christo Venter, Meghan Tanner, Monica Barnard, B. Bi, Yvonne Becherini, Colas Rivière, Iftach Sadeh, Lott Frans, Mischa Breuhaus, Pauline Chambery, C. Levy, Jose Luis García-Luna, Michelle Tsirou, D. Malyshev, Ramiro Torres Escobedo, Hassan Abdalla, Hambeleleni Ndiyavala, Chang Dong Rho, Jhilik Majumdar, Martin Pohl, Mathieu Bony, Oguzhan Anguener, Hend Yassin, Gwenael Giacinti, Manuel Meyer, Arturo Iriarte, John Matthews, Kirsty Feijen, Ahron S. Barber, Floriane Cangemi, Fernando Garfias, R. A. Ong, Thomas Weisgarber, Thomas Bylund, Gilgamesh Luis-Raya, Rowan Batzofin, Mathieu Naurois, Jacques Muller, Avery Archer, Andreas Quirrenbach, Anushka Udara Abeysekara, José Serna-Franco, Hugo Alberto Ayala Solares, Davit Zargaryan, Rubén López-Coto, Reshmi Mukherjee, Andreas Zmija, Guillem Marti'i-Devesa, Sameer Patel, M. Lemoine-Goumard, Roberto Noriega-Papaqui, Gaëtan Fichet de Clairfontaine, Axel Donath, A. W. Chen, Michael Kreter, Yunior Pérez Araujo, Anna Lia Longinotti, Michael Zacharias, Kleopas Shiningayamwe, Robert Brose, Fabian Schüssler, Emmanuel Moulin, Patrick Moriarty, Edna Ruiz Velasco, Michael Newbold, Oscar Chaparro-Amaro, J. T. Linnemann, Lenka Tomankova, Jodi Christiansen, Jaqueline Catalano, Ian James Watson, R. Konno, Andrew Taylor, C. Arcaro, Jason John Watson, Gavin Rowell, Daniel Omar Avila Rojas, Denys Malyshev, Emmet Roache, Rhiannon Turner, Chad Brisbois, Mohanraj Senniappan, José Roberto Angeles Camacho, Daniel Nieto, V. Poireau, Jimmy N.S. Shapopi, G. Vasileiadis, Hannah Dalgleish, donggeun tak, Juan Carlos Díaz Vélez, Armelle Jardin-Blicq, N. Zywucka, Abe Falcone, Nicola Omodei, Matthieu Renaud, German Hermann, Paul Morris, Maria Haupt, Stefan Klepser, Christopher van Eldik, Rafal Moderski, Alessandro Montanari, Amy Furniss, Sylvia Zhu, P. J. Meintjes, David Berge, Jose Andres Garcia-Gonzalez, Humberto Ibarguen Salazar, Wayne Robert Springer, Heike Prokoph, Marion Spir-Jacob, Amid Nayerhoda, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Annecy de Physique des Particules (LAPP), Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS
Subjects: Cherenkov detector, air, Cherenkov counter: water, Physics beyond the Standard Model, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, satellite, FOS: Physical sciences, IACT, Astrophysics, 01 natural sciences, GLAST, dark matter, law.invention, law, HESS, 0103 physical sciences, 010306 general physics, Cherenkov radiation, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Annihilation, 010308 nuclear & particles physics, background, new physics, imaging, sensitivity, MAGIC, Galaxy, Automatic Keywords, annihilation, VERITAS, galaxy, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], statistical, HAWC, Fermi Gamma-ray Space Telescope
Abstract: 36th International Cosmic Ray Conference, ICRC2019, Madison, USA, 24 Jul 2019 - 1 Aug 2019; 9 pages (2019)., The search for Dark Matter (DM) has great potential to reveal physics beyond the Standard Model. As such, searches for evidence of DM particles are being carried out using a wide range of techniques, such as direct searches for DM particles, searches for DM produced with colliders, and indirect searches for the Standard Model annihilation products of DM. Dwarf spheroidal galaxies (dSphs) are excellent targets for indirect Dark Matter searches due to their relatively high DM content and negligible expected astrophysical background. A collaboration was formed to maximise the sensitivity of DM searches towards dSphs by combining for the first time dSph data from three imaging air Cherenkov telescope (IACT) arrays: HESS, MAGIC, and VERITAS; the Fermi-LAT satellite, and the water Cherenkov detector HAWC. Due to the diverse nature of the instruments involved, each experiment will analyse their individual datasets from multiple targets and then the results will be combined at the likelihood level. For consistency of the likelihoods across the five experiments, a common approach is used to treat the astrophysical factor (J-Factor) for each target and an agreed set of annihilation channels are considered. We also agree on a common statistical approach and treatment of instrumental systematic uncertainties. The results are presented in terms of constraints on the velocity-weighted cross section for DM self-annihilation as a function of the DM particle mass.
Published: 2019
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34. Optimal strategies for observation of active galactic nuclei variability with Imaging Atmospheric Cherenkov Telescopes

Author: Gernot Maier, Matteo Giomi, and Lucie Gerard
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Active galactic nucleus, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Cherenkov Telescope Array, Light curve, 01 natural sciences, Duty cycle, Sky, Observatory, 0103 physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Small field of view, Cherenkov radiation, media_common
Abstract: Variable emission is one of the defining characteristic of active galactic nuclei (AGN). While providing precious information on the nature and physics of the sources, variability is often challenging to observe with time- and field-of-view-limited astronomical observatories such as Imaging Atmospheric Cherenkov Telescopes (IACTs). In this work, we address two questions relevant for the observation of sources characterized by AGN-like variability: what is the most time-efficient way to detect such sources, and what is the observational bias that can be introduced by the choice of the observing strategy when conducting blind surveys of the sky. Different observing strategies are evaluated using simulated light curves and realistic instrument response functions of the Cherenkov Telescope Array (CTA), a future gamma-ray observatory. We show that strategies that makes use of very small observing windows, spread over large periods of time, allows for a faster detection of the source, and are less influenced by the variability properties of the sources, as compared to strategies that concentrate the observing time in a small number of large observing windows. Although derived using CTA as an example, our conclusions are conceptually valid for any IACTs facility, and in general, to all observatories with small field of view and limited duty cycle., Comment: 14 pages, 11 figures
Published: 2016

35. Search for the imprint of axion-like particles in the highest-energy photons of hard γ-ray blazars

Author: R. Buehler, Aaron Dominguez, Gernot Maier, Marcos López, Manuel Meyer, and Galo Gallardo
Subjects: Photon, Astrophysics::High Energy Astrophysical Phenomena, Physics beyond the Standard Model, magnetic field, Astrophysics, Parameter space, 01 natural sciences, dark matter, GLAST, blazar, Physics::Geophysics, statistical analysis, 0103 physical sciences, ddc:530, numerical calculations, Axion, Physics, new physics, 010308 nuclear & particles physics, energy [photon], Astronomy and Astrophysics, photon: energy, Redshift, Magnetic field, gamma ray, axion-like particles, Intergalactic travel, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract: Journal of cosmology and astroparticle physics 2009(09), 1-20 (2020). doi:10.1088/1475-7516/2020/09/027, Axion-like particles (ALPs), predicted in theories beyond the Standard Model, can have observational effects on the transparency of the Universe to γ rays in the presence of magnetic fields. In this work, we search for effects compatible with the existence of ALPs with 80 months of data from the Fermi Large Area Telescope, by comparing the distributions of observed highest energy photons from sources beyond redshifts of z &geq; 0.1 with theoretical predictions in the presence of ALPs. We find no evidence for an increased γ-ray transparency due to ALPs and therefore we set limits on the ALPs parameters assuming a value of the intergalactic magnetic field strength of 1 nG. Photon-ALP couplings above $10^{−11}$ $GeV^{−1}$ are excluded for ALP masses $m_a$ &lesssim; 3.0 neV . As the allowed magnetic field parameter space is large, we also test lower magnetic field strengths and no constraints can be set for B&leq;0.1 nG below the CAST limit. These constraints exclude a region of the parameter space not covered by other $γ$-ray telescopes and are compatible with limits imposed by other experiments., Published by IOP, London
Published: 2020

36. Evidence for Proton Acceleration up to TeV Energies Based on VERITAS and Fermi-LAT Observations of the Cas A SNR

Author: Anushka Udara Abeysekara, M. J. Lang, A. Archer, K. Pfrang, P. Kaaret, O. Hervet, Gernot Maier, David A. Williams, Wystan Benbow, G. H. Gillanders, David Kieda, S. O'Brien, P. T. Reynolds, I. Sadeh, T. B. Humensky, Robert Brose, Frank Krennrich, A. J. Chromey, John L. Quinn, D. S. Hanna, P. Moriarty, James Buckley, Orel Gueta, Lucy Fortson, Augusto Ghiotto, Ralph Bird, N. Kelley-Hoskins, Q. Feng, P. Wilcox, A. Petrashyk, A. Gent, M. Kertzman, S. Das, E. Roache, E. Pueschel, M. Nievas-Rosillo, P. Kar, Vikram V. Dwarkadas, Martin Pohl, R. A. Ong, Karlen Shahinyan, Marcos Santander, Tarek M. Hassan, Reshmi Mukherjee, N. H. Park, A. Weinstein, C. Giuri, M. Buchovecky, Jamie Holder, Gordon T. Richards, G. H. Sembroski, A. D. Falcone, J. P. Finley, I. Sushch, G. Hughes, Weiguang Cui, Maria Krause, A. Wilhelm, S. Kumar, B. Zitzer, M. K. Daniel, T. J. Williamson, and K. Ragan
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, Particle physics, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Hadron, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), 01 natural sciences, Pion, Cover (topology), Space and Planetary Science, 0103 physical sciences, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Supernova remnant, 010303 astronomy & astrophysics, Energy (signal processing), 0105 earth and related environmental sciences, Fermi Gamma-ray Space Telescope
Abstract: We present a study of $\gamma$-ray emission from the core-collapse supernova remnant Cas~A in the energy range from 0.1GeV to 10TeV. We used 65 hours of VERITAS data to cover 200 GeV - 10 TeV, and 10.8 years of \textit{Fermi}-LAT data to cover 0.1-500 GeV. The spectral analysis of \textit{Fermi}-LAT data shows a significant spectral curvature around $1.3 \pm 0.4_{stat}$ GeV that is consistent with the expected spectrum from pion decay. Above this energy, the joint spectrum from \textit{Fermi}-LAT and VERITAS deviates significantly from a simple power-law, and is best described by a power-law with spectral index of $2.17\pm 0.02_{stat}$ with a cut-off energy of $2.3 \pm 0.5_{stat}$ TeV. These results, along with radio, X-ray and $\gamma$-ray data, are interpreted in the context of leptonic and hadronic models. Assuming a one-zone model, we exclude a purely leptonic scenario and conclude that proton acceleration up to at least 6 TeV is required to explain the observed $\gamma$-ray spectrum. From modeling of the entire multi-wavelength spectrum, a minimum magnetic field inside the remnant of $B_{\mathrm{min}}\approx150\,\mathrm{\mu G}$ is deduced., Comment: 33 pages, 9 Figures, 6 Tables
Published: 2020

37. A Decade of Multiwavelength Observations of the TeV Blazar 1ES 1215+303: Extreme Shift of the Synchrotron Peak Frequency and Long-term Optical–Gamma-Ray Flux Increase

Author: Tuomas Savolainen, S. S. Scott, K. Nilsson, A. Wilhelm, Walter Max-Moerbeck, S. O'Brien, Alasdair E. Gent, Nahee Park, A. N. Otte, K. Ragan, R. A. Ong, G. H. Sembroski, K. Pfrang, Merja Tornikoski, T. J. Williamson, Wei Cui, Sebastian Kiehlmann, R. Shang, Marita Krause, Anushka Udara Abeysekara, Philip G. Edwards, Amy Furniss, P. Kaaret, A. Pichel, Gernot Maier, Alexander B. Pushkarev, D. Horan, Anne Lähteenmäki, Jamie Holder, V. V. Vassiliev, B. G. Piner, Lucy Fortson, A. Brill, P. Moriarty, Karlen Shahinyan, Tarek M. Hassan, Denis Bernard, J. H. Buckley, G. Hughes, M. Pohl, I. Sushch, M. Kertzman, A. C. S. Readhead, J. Valverde, Robert Brose, Wystan Benbow, Q. Feng, John L. Quinn, Daniel Nieto, Stephen Fegan, M. Nievas-Rosillo, D. Ribeiro, M. Buchovecky, Giuliana Noto, T. B. Humensky, Jenni Jormanainen, F. Krennrich, Talvikki Hovatta, M. J. Lang, A. Petrashyk, R. R. Prado, V. Fallah Ramazani, J. P. Finley, Jodi Christiansen, P. Wilcox, Olivier Hervet, A. J.R. Weinstein, A. D. Falcone, Matthew L. Lister, D. S. Hanna, N. Kelley-Hoskins, Ralph Bird, I. Sadeh, David A. Williams, Gordon T. Richards, A. Archer, E. Roache, D. B. Kieda, Orel Gueta, L. O. Takalo, G. H. Gillanders, Yuri Y. Kovalev, P. T. Reynolds, E. Lindfors, Marcos Santander, Reshmi Mukherjee, C. Giuri, R. M. Wells, E. Pueschel, 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), Fermi-LAT, VERITAS, Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), University of Turku, Metsähovi Radio Observatory, Anne Lähteenmäki Group, Department of Electronics and Nanoengineering, Aalto-yliopisto, and Aalto University
Subjects: 010504 meteorology & atmospheric sciences, Infrared, Flux, Astrophysics, 4/3, 01 natural sciences, law.invention, law, Jets, Broadband, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma ray, Optical polarization, Galaxies: active, gamma-rays, Synchrotron, Wavelength, gamma ray: emission, optical [polarization], infrared, BL Lacertae objects, VERITAS, Astrophysics - High Energy Astrophysical Phenomena, Gamma-rays, ON 325, jets, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, GLAST, blazar, X-ray, emission [gamma ray], synchrotron, 0103 physical sciences, polarization: optical, Blazar, 0105 earth and related environmental sciences, B2 1215+30, S3 1215+30), Astronomy and Astrophysics, flux, 13. Climate action, Space and Planetary Science, correlation, Active galaxies, ddc:520, blazars BL Lacertae objects: individ- ual: 1ES 1215+303 (Ton 605, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Blazars
Abstract: Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multi-wavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from 100 MeV to 30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by VLBA at 43.1, 22.2, and 15.3 GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed., Comment: Accepted for publication in the Astrophysical Journal
Published: 2020

38. A Very High Energy gamma-Ray Survey toward the Cygnus Region of the Galaxy

Author: M. Buchovecky, Ralph Bird, R. A. Ong, M. K. Daniel, D. S. Hanna, P. Moriarty, A. Wilhelm, M. Kertzman, A. Weinstein, E. Pueschel, Marcos Santander, C. B. Rulten, A. Flinders, Maria Krause, R. M. Wells, A. N. Otte, John L. Quinn, Julien Rousselle, Q. Feng, S. McArthur, V. Bugaev, P. T. Reynolds, P. Kaaret, Gordon T. Richards, T. Aune, N. H. Park, G. Hughes, David Kieda, E. Roache, K. Huang, Vladimir Vassiliev, Gernot Maier, B. Zitzer, Moritz Hütten, Lucy Fortson, Olivier Hervet, Wystan Benbow, S. P. Wakely, M. J. Lang, C. A. Johnson, Martin Pohl, Amy Furniss, Abraham D. Falcone, Karlen Shahinyan, A. Archer, J. Tyler, Henrike Fleischhack, David A. Williams, K. Ragan, N. Kelley-Hoskins, Jamie Holder, Dirk Pandel, G. H. Sembroski, J. P. Finley, T. B. Humensky, R. Mukherjee, T. T.Y. Lin, A. Popkow, S. Kumar, P. Wilcox, Robert Brose, J. Grube, J. E. Ward, A. Petrashyk, P. Kar, Wei Cui, I. Sadeh, S. O'Brien, Anushka Udara Abeysekara, and Eric V. Gotthelf
Subjects: Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Institut für Physik und Astronomie, Astronomy and Astrophysics, Context (language use), Cosmic ray, Quasar, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar wind nebula, Crab Nebula, Pulsar, 13. Climate action, Space and Planetary Science, 0103 physical sciences, ddc:530, Supernova remnant, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Fermi Gamma-ray Space Telescope
Abstract: We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) $\gamma$-ray data taken with the VERITAS Cherenkov telescope array and over seven years of high-energy $\gamma$-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse $\gamma$-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130), and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL 2021.0+4031e (the Gamma-Cygni supernova remnant) was examined and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE $\gamma$-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula ux. We interpret these observations in a multiwavelength context and present the most detailed $\gamma$-ray view of the region to date., Comment: 49 Pages, 22 Figures, 13 Tables, Accepted to ApJ
Published: 2018

39. Performance optimization of the air shower simulation program for the Cherenkov Telescope Array

Author: Gernot Maier, Guillaume Revy, David Parello, Luisa Arrabito, Philippe Langlois, J. Bregeon, Konrad Bernlöhr, Laboratoire Univers et Particules de Montpellier (LUPM), 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 de Perpignan Via Domitia (UPVD), CTA Consortium, 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: Cherenkov Telescope Array, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Real-time computing, CPU time, 02 engineering and technology, computer.software_genre, 7. Clean energy, programming, 020204 information systems, 0202 electrical engineering, electronic engineering, information engineering, ddc:530, [INFO]Computer Science [cs], SIMD, Cherenkov radiation, showers: atmosphere, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, 020207 software engineering, Program optimization, Air shower, Grid computing, Central processing unit, data management, numerical calculations: Monte Carlo, computer, performance
Abstract: International audience; The Cherenkov Telescope Array (CTA), currently under construction, is the next-generation instrument in the field of very high energy gamma-ray astronomy. The first data are expected by the end of 2018, while the scientific operations will start in 2022 for a duration of about 30 years. In order to characterize the instrument response to the Cherenkov light emitted when cosmic ray showers develop in the atmosphere, detailed Monte Carlo simulations will be regularly performed in parallel to CTA operation. The estimated CPU time associated to these simulations is very high, of the order of 200 millions HS06 hours per year. Reducing the CPU time devoted to simulations would allow either to reduce infrastructure cost or to better cover the large phase space. In this paper, we focus on the main computing step (70% of the whole CPU time) implemented in the CORSIKA program, and specifically on the mod-ule responsible for the propagation of Cherenkov photons in the atmosphere. We present our preliminary studies about different options of code optimization, with a particular focus on vectorization facilities (SIMD instructions). Our proposals take care, as automatically as possible, of the hardware portability constraints introduced by the grid computing environment that hosts these simulations. Performance evaluation in terms of running-time and accuracy is provided.
Published: 2018

40. Observing small-scale gamma-ray anisotropies with the Cherenkov Telescope Array

Author: Gernot Maier and Moritz Hütten
Subjects: Cherenkov Telescope Array, Scale (ratio), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, anisotropy, 01 natural sciences, annihilation [dark matter], GLAST, VHE, blazar, 0103 physical sciences, ddc:530, structure, AGN, Anisotropy, Blazar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, density, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Galaxy, galaxy, Astrophysics - High Energy Astrophysical Phenomena, background [gamma ray], performance, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Disentangling the composition of the diffuse gamma-ray background (DGRB) is a major challenge in gamma-ray astronomy. It is presumed that at the highest energies, the DGRB is dominated by relatively few, still unresolved point sources. This conjecture has recently been supported by the measurement of small-scale anisotropies in the DGRB by the Fermi Large Area Telescope (LAT) up to energies of 500 GeV. We show how such anisotropies can be searched for with the forthcoming Earth-bound Cherenkov Telescope Array (CTA) up to the TeV range. We investigate different observation modes to analyse CTA data for small-scale anisotropies and propose the projected extragalactic large-area sky survey as the most promising data set. Relying on an up-to-date model of the performance of the southern CTA, we find that CTA will be able to probe anisotropies in the DGRB from unresolved point sources at a relative amplitude of $C_{\rm P}^I/I^2_{\rm DGRB}\gtrsim 4\times 10^{-3}\,{\rm sr}$ at energies above 30 GeV and angular scales $\lesssim 1.5^{\circ}$. Such DGRB anisotropies have not yet been ruled out by the Fermi-LAT. The proposed analysis would primarily clarify the contribution from blazars and misaligned active galactic nuclei to the very-high-energy regime of the DGRB, as well as provide insight into dark matter annihilation in Galactic and extragalactic density structures. Finally, it constitutes a measurement with complementary systematic uncertainties compared to the Fermi-LAT., Comment: 21 pages, 11 figures. V2 matches version published in JCAP (results unchanged)
Published: 2018
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41. The Cherenkov Telescope Array potential for the study of young supernova remnants

Author: Tomasz Szepieniec, K. Nishijima, T. Grabarczyk, M. C. Maccarone, Thomas Lohse, F. de Palma, Jacek Niemiec, R. J. García López, S. Rainò, Stefan Ohm, G. Busetto, F. Nunio, G. Pareschi, Emmanuel Moulin, Michał Szanecki, Jiri Chudoba, Saverio Lombardi, M. Nievas, Massimo Persic, A. Wilhelm, A. Bonardi, D. Garrido, J. L. Dournaux, A. Förster, Vikram V. Dwarkadas, Juan Abel Barrio, F. Di Pierro, K. Meagher, A. C. Rovero, Paweł Wójcik, Martina Bohacova, A. Sillanpää, Giuseppe Malaguti, R. A. Ong, Jörg R. Hörandel, Włodek Kluźniak, Henrike Fleischhack, Valerie Connaughton, Juhani Huovelin, Dusan Mandat, B. De Lotto, M. Palatka, Francesco Dazzi, A. De Franco, Carla Aramo, Martin Pohl, Anton N. Baushev, H. Siejkowski, G. Lamanna, David Berge, P. Vallania, M. Shayduk, C. van Eldik, N. Giglietto, Alicja Wierzcholska, S. Kaufmann, A. Giuliani, T. B. Humensky, T. Di Girolamo, R. López-Coto, L. Tibaldo, Masatoshi Ohishi, Pratik Majumdar, Luis Ángel Tejedor, B. S. Acharya, B. García, Gernot Maier, D. Nosek, Gagik Tovmassian, J.-P. Lenain, B. Khélifi, Takanori Yoshikoshi, Stanislav Stefanik, P. M. Chadwick, I. de la Calle, Garret Cotter, Masahiro Teshima, M. Fesquet, S. P. Wakely, William H. Lee, Andreas Quirrenbach, U. F. Katz, M. Garczarczyk, P. Romano, P. A. Caraveo, O. Tibolla, Marek Jamrozy, Nikola Godinovic, N. Otte, Hidetoshi Kubo, M. Fuessling, G. Fontaine, Rodolfo Carosi, Tarek M. Hassan, S. Vercellone, R. de los Reyes Lopez, Vito Conforti, Carlo Vigorito, Ll. Font, M. Prouza, V. Bugaev, Petr Travnicek, M. Hrabovsky, Jan Ebr, G. Rodriguez Fernandez, Miroslav Pech, Reiko Orito, J. Kocot, Ana Babić, A. Morselli, A. M. Brown, B. Rudak, M. N. Mazziotta, Kathrin Egberts, F. Lucarelli, Nukri Komin, J. Kushida, Jose Luis Contreras, Ferdinando Giordano, Alicia López-Oramas, J. Carr, Nestor Mirabal, C. Di Giulio, P. Kaaret, Petr Janecek, M. Trzeciak, Stefan Wagner, T. Stolarczyk, M. Gaug, Michael G. Burton, Petr Schovanek, A. Weinstein, Maria Magdalena González, I. Telezhinsky, J. Becker Tjus, F. Gargano, Dario Hrupec, Tomasz Bulik, 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), 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), 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 de Physique Nucléaire et de Hautes Énergies (LPNHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), CTA Collaboration, 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 Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), High Energy Astrophys. & Astropart. Phys (API, FNWI), Acharya, B. S., Aramo, C., Babic, A., Barrio, J. A., Baushev, A., Becker Tjus, J., Berge, D., Bohacova, M., Bonardi, A., Brown, A., Bugaev, V., Bulik, T., Burton, M., Busetto, G., Caraveo, P., Carosi, R., Carr, J., Chadwick, P., Chudoba, J., Conforti, V., Connaughton, V., Contreras, J. L., Cotter, G., Dazzi, F., De Franco, A., de la Calle, I., de los Reyes Lopez, R., De Lotto, B., De Palma, F., DI GIROLAMO, Tristano, Di Giulio, C., Di Pierro, F., Dournaux, J. L., Dwarkadas, V., Ebr, J., Egberts, K., Fesquet, M., Fleischhack, H., Font, L., Fontaine, G., Förster, A., Fuessling, M., Garcia, B., Garcia López, R., Garczarczyk, M., Gargano, F., Garrido, D., Gaug, M., Giglietto, N., Giordano, F., Giuliani, A., Godinovic, N., Gonzalez, M. M., Grabarczyk, T., Hassan, T., Hörandel, J., Hrabovsky, M., Hrupec, D., Humensky, T. B., Huovelin, J., Jamrozy, M., Janecek, P., Kaaret, P. E., Katz, U., Kaufmann, S., Khélifi, B., Kluźniak, W., Kocot, J., Komin, N., Kubo, H., Kushida, J., Lamanna, G., Lee, W. H., Lenain, J. P., Lohse, T., Lombardi, S., López Coto, R., López Oramas, A., Lucarelli, F., Maccarone, M. C., Maier, G., Majumdar, P., Malaguti, G., Mandat, D., Mazziotta, M. N., Meagher, K., Mirabal, N., Morselli, A., Moulin, E., Niemiec, J., Nievas, M., Nishijima, K., Nosek, D., Nunio, F., Ohishi, M., Ohm, S., Ong, R. A., Orito, R., Otte, N., Palatka, M., Pareschi, G., Pech, M., Persic, M., Pohl, M., Prouza, M., Quirrenbach, A., Rainó, S., Rodriguez Fernandez, G., Romano, P., Rovero, A. C., Rudak, B., Schovanek, P., Shayduk, M., Siejkowski, H., Sillanpää, A., Stefanik, S., Stolarczyk, T., Szanecki, M., Szepieniec, T., Tejedor, L. A., Telezhinsky, I., Teshima, M., Tibaldo, L., Tibolla, O., Tovmassian, G., Travnicek, P., Trzeciak, M., Vallania, P., van Eldik, C., Vercellone, S., Vigorito, C., Wagner, S. J., Wakely, S. P., Weinstein, A., Wierzcholska, A., Wilhelm, A., Wojcik, P., and Yoshikoshi, T.
Subjects: Non-termal. [Radiation mechanisms], [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Acceleration of particles, PARTICLE-ACCELERATION, GAMMA RAYS, Ciencias Físicas, Milky Way, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Cosmic ray, Astrophysics, 7. Clean energy, REVERSE SHOCKS, Gamma rays: General, ISM: Supernova remnants, Radiation mechanisms: Non-termal, General, non-termal [radiation mechanisms], Cherenkov radiation, Astrophysics::Galaxy Astrophysics, acceleration of particles, Physics, CTA, supernova remnants [ISM], MAGNETIC-FIELD, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, AMPLIFICATION, Gamma-ray astronomy, Cherenkov Telescope Array, COSMIC-RAYS, DIFFUSIVE SHOCK ACCELERATION, GAMMA-RAY ASTRONOMY, CASSIOPEIA-A, MILKY-WAY, EMISSION, Astronomía, Particle acceleration, Cassiopeia A, Supernova, SUPERNOVA REMNANTS, ddc:540, general [gamma rays], CIENCIAS NATURALES Y EXACTAS
Abstract: Supernova remnants (SNRs) are among the most important targets for γ-ray observatories. Being prominent non-thermal sources, they are very likely responsible for the acceleration of the bulk of Galactic cosmic rays (CRs). To firmly establish the SNR paradigm for the origin of cosmic rays, it should be confirmed that protons are indeed accelerated in, and released from, SNRs with the appropriate flux and spectrum. This can be done by detailed theoretical models which account for microphysics of acceleration and various radiation processes of hadrons and leptons. The current generation of Cherenkov telescopes has insufficient sensitivity to constrain theoretical models. A new facility, the Cherenkov Telescope Array (CTA), will have superior capabilities and may finally resolve this long standing issue of high-energy astrophysics. We want to assess the capabilities of CTA to reveal the physics of various types of SNRs in the initial 2000 years of their evolution. During this time, the efficiency to accelerate cosmic rays is highest. We perform time-dependent simulations of the hydrodynamics, the magnetic fields, the cosmic-ray acceleration, and the non-thermal emission for type Ia, Ic and IIP SNRs. We calculate the CTA response to the γ-ray emission from these SNRs for various ages and distances, and we perform a realistic analysis of the simulated data. We derive distance limits for the detectability and resolvability of these SNR types at several ages. We test the ability of CTA to reconstruct their morphological and spectral parameters as a function of their distance. Finally, we estimate how well CTA data will constrain the theoretical models. Fil: Acharya, B. S.. Tata Institute of Fundamental Research; India Fil: Aramo, C.. INFN; Italia Fil: Babic, A.. Rudjer Boskovic Institute; Croacia Fil: Barrio, J. A.. Universidad Complutense de Madrid; España Fil: Baushev, A.. Universität Potsdam; Alemania Fil: Becker Tjus, J.. Ruhr-universität Bochum; Alemania Fil: Berge, D.. University of Amsterdam; Países Bajos Fil: Bohacova, M.. Institute of Physics of the Academy of Sciences of the Czech Republic; República Checa Fil: Bonardi, A.. Universität Tübingen; Alemania Fil: Brown, A.. Durham University; Reino Unido Fil: Bugaev, V.. Washington University; Estados Unidos Fil: Bulik, T.. University of Warsaw; Polonia Fil: Burton, M.. University Of New South Wales; Australia Fil: Busetto, G.. Universitá degli Studi di Padova; Italia Fil: Caraveo, P.. Istituto di Astrofisica Spaziale e Fisica Cosmica; Italia Fil: Carosi, R.. INFN; Italia Fil: Carr, J.. Aix-Marseille Université; Francia Fil: Chadwick, P.. Durham University; Reino Unido Fil: Chudoba, J.. Institute of Physics of the Academy of Sciences of the Czech Republic; República Checa Fil: Conforti, V.. Istituto di Astrofisica Spaziale e Fisica Cosmica; Italia Fil: Connaughton, V.. University of Alabama; Estados Unidos Fil: Contreras, J. L.. Universidad Complutense de Madrid; España Fil: Cotter, G.. University of Oxford; Reino Unido Fil: Dazzi, F.. Universitá degli Studi di Padova; Italia Fil: De Franco, A.. t University of Oxford; Reino Unido Fil: de la Calle, I.. Universidad Complutense de Madrid; España Fil: de los Reyes Lopez, R.. Max-Planck-Institut für Kernphysik; Alemania Fil: De Lotto, B.. University of Udine; Italia Fil: Garcia, Beatriz Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Tecnologías en Detección y Astropartículas. Subsede del Instituto de Tecnologías en Detección y Astropartículas Mendoza; Argentina Fil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: The Cta Consortium.
Published: 2015

42. Very-high-energy γ-ray observations of the blazar 1es 2344+514 with veritas

Author: A. Flinders, R. Mukherjee, P. Kaaret, E. Pueschel, A. McCann, D. S. Hanna, Martin Pohl, Maria Krause, Wei Cui, R. A. Ong, David Kieda, F. Krennrich, Daniel Nieto, M. K. Daniel, Wystan Benbow, A. N. Otte, Sinéad M. Griffin, M. P. Connolly, A. Wilhelm, A. Archer, Robert Brose, Moritz Hütten, Cameron H. Allen, J. Grube, C. Rulten, A. Petrashyk, G. H. Gillanders, Etienne Bourbeau, Lucy Fortson, N. H. Park, A. C. Rovero, P. Kar, P. T. Reynolds, N. Håkansson, Henrike Fleischhack, Gordon T. Richards, J. V. Tucci, Gernot Maier, M. Kertzman, A. O'Faolain de Bhroithe, J. Tyler, G. H. Sembroski, Matteo Cerruti, G. Hughes, J. H. Buckley, S. Archambault, M. Buchovecky, Amy Furniss, S. P. Wakely, S. O'Brien, I. Sadeh, A. Popkow, Marcos Santander, Thanh Huy Nguyen, J. V. Cardenzana, C. A. Johnson, K. Ragan, Jodi Christiansen, P. Moriarty, Xuhui Chen, M. Fernandez-Alonso, K. Meagher, Q. Feng, T. B. Humensky, J. P. Finley, John L. Quinn, S. Kumar, A. Pichel, E. Roache, Abraham D. Falcone, Karlen Shahinyan, Ralph Bird, S. McArthur, V. Bugaev, O. Hervet, J. D. Eisch, A. Weinstein, M. J. Lang, N. Kelley-Hoskins, I. Telezhinsky, Jamie Holder, and David A. Williams
Subjects: gamma-rays: galaxies, Point source, Ciencias Físicas, bl-lacertae objects, Astrophysics, telescope, 01 natural sciences, Spectral line, spectrum, purl.org/becyt/ford/1 [https], 0103 physical sciences, emission, ASTROPARTICLE PHYSICS, Blazar, 010303 astronomy & astrophysics, Physics, GALAXIES [GAMMA-RAYS], 010308 nuclear & particles physics, variability, Attenuation, Gamma ray, Astronomy, Institut für Physik und Astronomie, background-radiation, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], bl lacertae objects: individual: 1es 2344+514=verj2347+517, Light curve, Astronomía, radio, Extragalactic background light, x-ray, Space and Planetary Science, astroparticle physics, active galactic nuclei, ddc:520, BL LACERTAE OBJECTS, Astrophysics - High Energy Astrophysical Phenomena, constraints, CIENCIAS NATURALES Y EXACTAS, BL Lac object
Abstract: We present very-high-energy $\gamma$-ray observations of the BL Lac object 1ES 2344+514 taken by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) between 2007 and 2015. 1ES 2344+514 is detected with a statistical significance above background of $20.8\sigma$ in $47.2$ hours (livetime) of observations, making this the most comprehensive very-high-energy study of 1ES 2344+514 to date. Using these observations the temporal properties of 1ES 2344+514 are studied on short and long times scales. We fit a constant flux model to nightly- and seasonally-binned light curves and apply a fractional variability test, to determine the stability of the source on different timescales. We reject the constant-flux model for the 2007-2008 and 2014-2015 nightly-binned light curves and for the long-term seasonally-binned light curve at the $> 3\sigma$ level. The spectra of the time-averaged emission before and after correction for attenuation by the extragalactic background light are obtained. The observed time-averaged spectrum above 200 GeV is satisfactorily fitted (${\chi^2/NDF = 7.89/6}$) by a power-law function with index $\Gamma = 2.46 \pm 0.06_{stat} \pm 0.20_{sys} $ and extends to at least 8 TeV. The extragalactic-background-light-deabsorbed spectrum is adequately fit (${\chi^2/NDF = 6.73/6}$) by a power-law function with index $\Gamma = 2.15 \pm 0.06_{stat} \pm 0.20_{sys} $ while an F-test indicates that the power-law with exponential cutoff function provides a marginally-better fit ($\chi^2/NDF $ = $2.56 / 5 $) at the 2.1$\sigma$ level. The source location is found to be consistent with the published radio location and its spatial extent is consistent with a point source., Comment: 7 pages, 2 figures. Published in Monthly Notices of the Royal Astronomical Society
Published: 2017

43. Gamma-ray observations of tycho’s supernova remnant with veritas andfermi

Author: Q. Feng, P. T. Reynolds, C. A. Johnson, Wystan Benbow, A. Popkow, J. P. Finley, D. S. Hanna, B. Zitzer, Manel Errando, S. Kumar, D. B. Kieda, Karlen Shahinyan, Daniel Nieto, Henrike Fleischhack, Gernot Maier, Lucy Fortson, Moritz Hütten, David A. Williams, S. O'Brien, J. Tyler, M. Pohl, P. Kaaret, R. A. Ong, Thomas Weisgarber, Nahee Park, S. McArthur, J. H. Buckley, G. H. Sembroski, I. Sadeh, P. Wilcox, I. Telezhinsky, Jamie Holder, John L. Quinn, E. Pueschel, M. Buchovecky, P. Moriarty, P. Kar, A. N. Otte, S. Trepanier, Patrick Slane, A. J.R. Weinstein, A. Wilhelm, Ralph Bird, M. P. Connolly, D. Staszak, K. Ragan, Wei Cui, A. Archer, Gordon T. Richards, M. J. Lang, Marcos Santander, E. Roache, A. D. Falcone, Etienne Bourbeau, S. Archambault, Reshmi Mukherjee, Dwarkadas, N. Kelley-Hoskins, Bugaev, Matteo Cerruti, Amy Furniss, Sinéad M. Griffin, M. Kertzman, A. McCann, S. P. Wakely, and Marita Krause
Subjects: molecular cloud, shock acceleration, Astrophysics::High Energy Astrophysical Phenomena, stars-supernovae, cosmic-rays, Astrophysics, Type (model theory), telescope, 01 natural sciences, 0103 physical sciences, emission, ddc:530, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Spectral index, Range (particle radiation), particle-acceleration, 010308 nuclear & particles physics, brahes 1572 supernova, data behind figure, Gamma ray, Center (category theory), magnetic-field, electrons, Institut für Physik und Astronomie, individual(tycho's snr) supporting material, Astronomy and Astrophysics, gamma rays, Supernova, Space and Planetary Science, ddc:520, High Energy Physics::Experiment, high-energy, Energy (signal processing), Fermi Gamma-ray Space Telescope
Abstract: The astrophysical journal 836(1), 23 (2017). doi:10.3847/1538-4357/836/1/23, High-energy gamma-ray emission from supernova remnants (SNRs) has provided a unique perspective for studies of Galactic cosmic-ray acceleration. Tycho's SNR is a particularly good target because it is a young, type Ia SNR that has been well-studied over a wide range of energies and located in a relatively clean environment. Since the detection of gamma-ray emission from Tycho's SNR by VERITAS and Fermi-LAT, there have been several theoretical models proposed to explain its broadband emission and high-energy morphology. We report on an update to the gamma-ray measurements of Tycho's SNR with 147 hr of VERITAS and 84 months of Fermi-LAT observations, which represent about a factor of two increase in exposure over previously published data. About half of the VERITAS data benefited from a camera upgrade, which has made it possible to extend the TeV measurements toward lower energies. The TeV spectral index measured by VERITAS is consistent with previous results, but the expanded energy range softens a straight power-law fit. At energies higher than 400 GeV, the power-law index is 2.92 ± 0.42$_{stat}$ ± 0.20$_{sys}$. It is also softer than the spectral index in the GeV energy range, 2.14 ± 0.09$_{stat}$ ± 0.02$_{sys}$, measured in this study using Fermi-LAT data. The centroid position of the gamma-ray emission is coincident with the center of the remnant, as well as with the centroid measurement of Fermi-LAT above 1 GeV. The results are consistent with an SNR shell origin of the emission, as many models assume. The updated spectrum points to a lower maximum particle energy than has been suggested previously., Published by IOP Publ., Chicago, Ill. [u.a.]
Published: 2017

44. Open high-level data formats and software for gamma-ray astronomy

Author: P. Eger, Matthew Wood, Regis Terrier, Gernot Maier, Daniela Dorner, Julien Lefaucheur, Saverio Lombardi, Kai Brügge, Jose Luis Contreras, Roland Walter, Tarek M. Hassan, Victor Zabalza, Mathieu Servillat, Bruno Khelifi, Catherine Boisson, Jeremy Perkins, Christoph Deil, A. Ziegler, Karl Kosack, Jürgen Knödlseder, Johannes King, Jaime Rosado, Lars Mohrmann, Michael Mayer, G. Pedaletti, Laboratoire Univers et Théories (LUTH (UMR_8102)), 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)-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, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), 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), 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 des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), 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), 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), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -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), 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), Laboratoire Univers et Théories ( LUTH ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -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, Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), AstroParticule et Cosmologie ( APC - UMR 7164 ), and Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )
Subjects: Cherenkov Telescope Array, Computer science, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], FOS: Physical sciences, Context (language use), IACT, feedback, Cherenkov counter: atmosphere, 01 natural sciences, programming, Software, Gammaastronomie, Observatory, 0103 physical sciences, Astrophysik, [INFO]Computer Science [cs], ddc:530, Mailing list, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, business.industry, imaging, Gammastrahlung, observatory, Open data, Data model, gamma ray, Física nuclear, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Software engineering, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: [Print] High energy gamma-ray astronomy : 6th International Meeting on High Energy Gamma-Ray Astronomy, Heidelberg, Germany, 11 - 15 July 2016 / Aharonian, Felix A. ; Hofmann, W. ; Rieger, Frank Michael , Melville, NY : AIP Publishing, 2017, 6th International Meeting on High Energy Gamma-Ray Astronomy, Heidelberg, Germany, 11 Jul 2016 - 15 Jul 2016; AIP conference proceedings 1792(1), 070006 (2017). doi:10.1063/1.4969003, n gamma-ray astronomy, a variety of data formats and proprietary software have been traditionally used, often developed for one specific mission or experiment. Especially for ground-based imaging atmospheric Cherenkov telescopes (IACTs), data and software are mostly private to the collaborations operating the telescopes. However, there is a general movement in science towards the use of open data and software. In addition, the next-generation IACT instrument, the Cherenkov Telescope Array (CTA), will be operated as an open observatory.We have created a Github organisation at https://github.com/open-gamma-ray-astro where we are developing high-level data format specifications. A public mailing list was set up at https://lists.nasa.gov/mailman/listinfo/open-gamma-ray-astro and a first face-to-face meeting on the IACT high-level data model and formats took place in April 2016 in Meudon (France). This open multi-mission effort will help to accelerate the development of open data formats and open-source software for gamma-ray astronomy, leading to synergies in the development of analysis codes and eventually better scientific results (reproducible, multi-mission).This write-up presents this effort for the first time, explaining the motivation and context, the available resources and process we use, as well as the status and planned next steps for the data format specifications. We hope that it will stimulate feedback and future contributions from the gamma-ray astronomy community., Published by Inst., Melville, NY
Published: 2017
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45. Monte Carlo Performance Studies for the Site Selection of the Cherenkov Telescope Array

Author: Matthew Wood, Luisa Arrabito, Gernot Maier, F. Di Pierro, Abelardo Moralejo, C. J. Todero Peixoto, Jim Hinton, T. Jogler, Konrad Bernlöhr, A. Morselli, Tarek M. Hassan, P. Cumani, Diego Falceta-Gonçalves, Johan Bregeon, Juan Cortina, Rodrigo Guedes Lang, 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 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), Laboratoire Univers et Particules de Montpellier ( LUPM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Université de Montpellier ( UM ), and 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)
Subjects: Cherenkov Telescope Array, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Site selection, FOS: Physical sciences, Cosmic ray, Site evaluation, 7. Clean energy, 01 natural sciences, photon: spatial distribution, Monte Carlo simulations, angular resolution: energy dependence, 0103 physical sciences, site, Cherenkov Telescopes, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010303 astronomy & astrophysics, Cosmic rays, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, Remote sensing, Physics, Cherenkov counter: design, 010308 nuclear & particles physics, background, Gamma rays, Gamma ray, IACT technique, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, sensitivity, magnetic field: effect, Earth's magnetic field, gamma ray: VHE, ddc:540, Astrophysics - Instrumentation and Methods for Astrophysics, numerical calculations: Monte Carlo, RAIOS CÓSMICOS, performance
Abstract: The Cherenkov Telescope Array (CTA) represents the next generation of ground-based instruments for very-high-energy (VHE) gamma-ray astronomy, aimed at improving on the sensitivity of current-generation experiments by an order of magnitude and providing coverage over four decades of energy. The current CTA design consists of two arrays of tens of imaging atmospheric Cherenkov telescopes, comprising Small, Medium and Large-Sized Telescopes, with one array located in each of the Northern and Southern Hemispheres. To study the effect of the site choice on the overall \gls{cta} performance and support the site evaluation process, detailed Monte Carlo simulations have been performed. These results show the impact of different site-related attributes such as altitude, night-sky background and local geomagnetic field on CTA performance for the observation of VHE gamma rays., Comment: 34 pages, 11 figures, Accepted for publication in APP
Published: 2017
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46. A luminous and isolated gamma-ray flare from the blazar B2 1215+30

Author: Veritas, Collaboration, Abeysekara, A. U., Archambault, S., Archer, A., Benbow, W., Bird, R., Buchovecky, M., Buckley, J. H., Bugaev, V., Byrum, K., Cerruti, M., Chen, X., Ciupik, L., Cui, W., Dickinson, H. J., Eisch, J. D., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Fleischhack, H., Fortson, L., Furniss, A., Gillanders, G. H., Griffin, S., Grube, J., Hutten, M., Hakansson, N., Hanna, D., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Gernot Maier, Mcarthur, S., Mccann, A., Meagher, K., Moriarty, P., Mukherjee, R., Nguyen, T., Nieto, D., Ong, R. A., Otte, A. N., Park, N., Pelassa, V., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rulten, C., Santander, M., Sembroski, G. H., Shahinyan, K., Staszak, D., Telezhinsky, I., Tucci, J. V., Tyler, J., Wakely, S. P., Weiner, O. M., Weinstein, A., Wilhelm, A., Williams, D. A., Fermi-LAT Collaboration, Fegan, S., Giebels, B., Horan, D., Berdyugin, A., Kuan, J., Lindfors, E., Nilsson, K., Oksanen, A., Prokoph, H., Reinthal, R., Takalo, L., Zefi, F., AstroParticule et Cosmologie (APC (UMR_7164)), 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), 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), 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), VERITAS, Fermi-LAT, 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), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), 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), AstroParticule et Cosmologie ( APC - UMR 7164 ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), 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 ), Laboratoire de Physique Nucléaire et de Hautes Énergies ( LPNHE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Paris Diderot - Paris 7 ( UPD7 ) -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), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: multiwavelength observations, 010504 meteorology & atmospheric sciences, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, swift ultraviolet/optical telescope, 01 natural sciences, law.invention, bl lacertae objects, law, Observatory, 0103 physical sciences, gamma rays: galaxies, Astrophysics::Solar and Stellar Astrophysics, ddc:530, MAGIC (telescope), Blazar, 010303 astronomy & astrophysics, Cherenkov radiation, 0105 earth and related environmental sciences, BL Lacertae objects: individual, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, particle-acceleration, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, source catalog, galaxies: jets, spectral energy-distributions, bl lacertae objects: individual (b2 1215+30, ver j1217+301), large-area telescope, Crab Nebula, Space and Planetary Science, active galactic nuclei, reconnection, ddc:520, galaxies: nuclei, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], discovery, Flare
Abstract: The astrophysical journal 836(2), 205 (2017). doi:10.3847/1538-4357/836/2/205, B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of $\lt 3.6\,\mathrm{hr}$. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a one-zone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor $\delta \gt 10$, and an electron population with spectral index $p\lt 2.3$., Published by IOP Publ., Chicago, Ill. [u.a.]
Published: 2017

47. Search for Magnetically Broadened Cascade Emission From Blazars with VERITAS

Author: Veritas, Collaboration, Archambault, S., Archer, A., Benbow, W., Buchovecky, M., Bugaev, V., Cerruti, M., Connolly, M. P., Cui, W., Falcone, A., Fernández Alonso, M., Finley, J. P., Fleischhack, H., Fortson, L., Furniss, A., Griffin, S., Hütten, M., Hervet, O., Holder, J., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kieda, D., Krause, M., Krennrich, F., Lang, M. J., Lin, T. T. Y., Gernot Maier, Mcarthur, S., Moriarty, P., Nieto, D., O Brien, S., Ong, R. A., Otte, A. N., Pohl, M., Popkow, A., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Sadeh, I., Shahinyan, K., Staszak, D., Telezhinsky, I., Tyler, J., Wakely, S. P., Weinstein, A., Weisgarber, T., Wilcox, P., Wilhelm, A., Williams, D. A., and Zitzer, B.
Subjects: extragalactic background light, Photon, GALAXIES [GAMMA RAYS], Ciencias Físicas, Cosmic microwave background, Astrophysics, magnetic fields, 7. Clean energy, 01 natural sciences, purl.org/becyt/ford/1 [https], pair halos, 010303 astronomy & astrophysics, ACTIVE [GALAXIES], fields, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Gamma ray, cosmic voids, universe, large-area telescope, Extragalactic background light, Cascade, ddc:53, GENERAL [BL LACERTAE OBJECTS], Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, gamma rays: galaxies, 0103 physical sciences, 010306 general physics, Blazar, Astrophysics::Galaxy Astrophysics, bl lacertae objects: general, gamma-ray observations, tev blazars, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], MAGNETIC FIELDS, radiation, Astronomía, 13. Climate action, Space and Planetary Science, active galactic nuclei, ddc:520, Intergalactic travel
Abstract: We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGN), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma rays from AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background (CMB) photons via inverse-Compton scattering to produce gamma rays. Due to the deflection of the electron-positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around $10^{-14}$G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission., Comment: Accepted for publication in The Astrophysical Journal
Published: 2017
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48. Improved $\gamma$/hadron separation for the detection of faint $\gamma$-ray sources using boosted decision trees

Author: E. Pueschel, Maria Krause, and Gernot Maier
Subjects: Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Signal, law.invention, Telescope, law, 0103 physical sciences, ddc:540, Alternating decision tree, Sensitivity (control systems), Astrophysics - Instrumentation and Methods for Astrophysics, Focus (optics), 010303 astronomy & astrophysics, Cherenkov radiation, Event (probability theory)
Abstract: Astroparticle physics 89, 1 - 9 (2017). doi:10.1016/j.astropartphys.2017.01.004, Imaging atmospheric Cherenkov telescopes record an enormous number of cosmic-ray background events. Suppressing these background events while retaining $\gamma$-rays is key to achieving good sensitivity to faint $\gamma$-ray sources. The differentiation between signal and background events can be accomplished using machine learning algorithms, which are already used in various fields of physics. Multivariate analyses combine several variables into a single variable that indicates the degree to which an event is $\gamma$-ray-like or cosmic-ray-like. In this paper we will focus on the use of “boosted decision trees” for $\gamma$/hadron separation. We apply the method to data from the Very Energetic Radiation Imaging Telescope Array System (VERITAS), and demonstrate an improved sensitivity compared to the VERITAS standard analysis., Published by Elsevier Science, Amsterdam [u.a.]
Published: 2017
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49. Eventdisplay: An Analysis and Reconstruction Package for Ground-based Gamma-ray Astronomy

Author: Gernot Maier and Jamie Holder
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Multivariate statistics, Computer science, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Function (mathematics), Gamma-ray astronomy, Image (mathematics), law.invention, Telescope, law, Computer graphics (images), Calibration, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM), TRACE (psycholinguistics)
Abstract: Eventdisplay is a software package for the analysis and reconstruction of data and Monte Carlo events from ground-based gamma-ray observatories such as VERITAS and CTA. It was originally developed as a display tool for data from the VERITAS prototype telescope, but evolved into a full analysis package with routines for calibration, FADC trace integration, image and stereo parameter analysis, response function calculation, and high-level analysis steps. Eventdisplay makes use of an image parameter analysis combined with gamma-hadron separation methods based on multivariate algorithms. An overview of the reconstruction methods and some selected results are presented in this contribution., Comment: 8 pages, 2 figures, in Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Busan (South Korea)
Published: 2017
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50. Performance of the Cherenkov Telescope Array

Author: Luisa Arrabito, Konrad Bernlöhr, Gernot Maier, Tarek M. Hassan, J. Bregeon, Abelardo Moralejo, P. Cumani, 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), CTA Consortium, 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: Cherenkov Telescope Array, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, energy resolution, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Observatory, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Image resolution, spatial resolution, activity report, Physics, 010308 nuclear & particles physics, Gamma ray spectrometer, Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, gamma ray: spectrometer, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, numerical calculations: Monte Carlo, performance
Abstract: The Cherenkov Telescope Array (CTA) will be the world's largest and by far most sensitive observatory for high-energy gamma rays. It will be capable of detecting gamma rays from extremely faint sources with unprecedented precision on energy and direction in the energy range from 20 GeV to more than 300 TeV. The performance of the future CTA observatory derived from detailed Monte Carlo simulations is presented in this contribution for the two CTA sites in Paranal (Chile) and on the La Palma island (Spain)., Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Bexco, Busan, Korea. All CTA contributions at arXiv:1709.03483
Published: 2017

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