Related papers: Spectral cutoffs in EGRET gamma-ray sources

Multi-Epoch Multiwavelength Spectra and Models for Blazar 3C~279

Of the blazars detected by EGRET in GeV gamma rays, 3C 279 is not only the best-observed by EGRET, but also one of the best-monitored at lower frequencies. We have assembled eleven spectra, from GHz radio through GeV gamma rays, from the…

Astrophysics · Physics 2009-11-06 R. C. Hartman , M. Boettcher

Search for point sources and diffuse emission from the Galactic plane with the HEGRA-IACT-system

The HEGRA-IACT-system with a FoV of ~1.5 deg radius has been used for surveying one quater of the Galactic disc in respect to point sources, moderately extended sources and for diffuse emission in the energy range above 1 TeV. In total 140…

Astrophysics · Physics 2007-05-23 H. Lampeitl , K. Bernloehr , A. Daum , W. Hofmann , A. Konopelko , G. Puehlhofer , HEGRA-Collaboration

Gamma-Hadron Separation in Very-High-Energy gamma-ray astronomy using a multivariate analysis method

In recent years, Imaging Atmospheric Cherenkov Telescopes (IACTs) have discovered a rich diversity of very high energy (VHE, > 100 GeV) gamma-ray emitters in the sky. These instruments image Cherenkov light emitted by gamma-ray induced…

Instrumentation and Methods for Astrophysics · Physics 2009-05-27 Stefan Ohm , Christopher van Eldik , Kathrin Egberts

Uncovering the Spectral Energy Distribution in Active Galaxies Using High Ionization Mid-infrared Emission Lines

The shape of the spectral energy distribution of active galaxies in the EUV--soft X-ray band (13.6 eV to 1 keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the spectral…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 M. Meléndez , S. B. Kraemer , K. A. Weaver , R. F. Mushotzky

Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 Gigaelectronvolts (GeV) with the VERITAS array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar…

High Energy Astrophysical Phenomena · Physics 2011-10-24 VERITAS Collaboration , E. Aliu , T. Arlen , T. Aune , M. Beilicke , W. Benbow , A. Bouvier , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , J. L. Christiansen , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , R. Dickherber , C. Duke , M. Errando , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , K. Gibbs , G. H. Gillanders , S. Godambe , S. Griffin , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , H. Huan , G. Hughes , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , M. Lyutikov , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , M. McCutcheon , P. Moriarty , R. Mukherjee , P. Nuñez , R. A. Ong , M. Orr , A. N. Otte , N. Park , J. S. Perkins , F. Pizlo , M. Pohl , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , J. Rose , J. Ruppel , D. B. Saxon , M. Schroedter , G. H. Sembroski , G. D. Şentürk , A. W. Smith , D. Staszak , G. Tešić , M. Theiling , S. Thibadeau , K. Tsurusaki , J. Tyler , A. Varlotta , V. V. Vassiliev , S. Vincent , M. Vivier , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , B. Zitzer

An optical view of extragalactic gamma-ray emitters

The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy from 100 MeV to 100 GeV. The majority of these sources belong to the class of blazars characterized by a quasi-featureless optical spectrum…

Astrophysics of Galaxies · Physics 2017-11-02 Simona Paiano , Renato Falomo , Marco Landoni , Aldo Treves , Riccardo Scarpa

Constraining the Photon Intensity of Extragalactic Background Light with the HAWC Observatory for the Blazar Mrk 421

The blazar Mrk 421 exhibits rapid variability over a wide range of timescales. Spectral differences have been observed during the different emission states of Mrk 421. During the high emission states, tests to constraint the Hubble constant…

High Energy Astrophysical Phenomena · Physics 2026-05-25 R. Alfaro , C. Alvarez , A. Andrés , E. Anita-Rangel , M. Araya , J. C. Arteaga-Velázquez , D. Avila Rojas , R. Babu , P. Bangale , E. Belmont-Moreno , A. Bernal , T. Capistrán , A. Carramiñana , F. Carreón , A. L. Colmenero-Cesar , U. Cotti , J. Cotzomi , S. Coutiño de León , N. Di Lalla , R. Diaz Hernandez , B. L. Dingus , M. A. DuVernois , T. Ergin , C. Espinoza , N. Fraija , S. Fraija , J. A. García-González , F. Garfias , J. A. González , N. Ghosh , A. Gonzalez Muñoz , M. M. González , J. A. Goodman , S. Groetsch , J. Gyeong , S. Hernández-Cadena , I. Herzog , F. Hueyotl-Zahuantitla , D. Huang , A. Iriarte , S. Kaufmann , D. Kieda , H. León Vargas , A. L. Longinotti , G. Luis-Raya , K. Malone , O. Martinez , J. Martínez-Castro , H. Martínez-Huerta , P. Miranda-Romagnoli , P. E. Mirón-Enriquez , E. Moreno , M. Mostafá , M. Najafi , L. Nellen , M. U. Nisa , R. Noriega-Papaqui , M. Osorio-Archila , E. Ponce , Y. Pérez Araujo , E. G. Pérez-Pérez , A. Pratts , C. D. Rho , D. Rosa-González , M. Roth , A. Sandoval , M. Shin , A. J. Smith , Y. Son , R. W. Springer , O. Tibolla , I. Torres , R. Torres-Escobedo , E. Varela , L. Villaseñor , X. Wang , I. J. Watson , H. Wu , S. Yu , X. Zhang , H. Zhou , C. de León

Detection of Low-energy Breaks in Gamma-Ray Burst Prompt Emission Spectra

The radiative process responsible for gamma-Ray Burst (GRB) prompt emission has not been identified yet. If dominated by fast-cooling synchrotron radiation, the part of the spectrum immediately below the $\nu F_\nu$ peak energy should…

High Energy Astrophysical Phenomena · Physics 2017-09-20 Gor Oganesyan , Lara Nava , Giancarlo Ghirlanda , Annalisa Celotti

Intrinsic GeV-TeV gamma-ray emission from EHSP blazars

Extremely High Synchrotron Peak (EHSP) blazars are observed to form a small population of sources with high energy hump peaking at TeV energies in their broad-band spectral energy distributions. The observed gamma-ray emission from these…

High Energy Astrophysical Phenomena · Physics 2019-07-29 K. K. Singh , P. J. Meintjes , N. Bhatt , B. van Soelen

A Monte Carlo Study of the Irreducible Background in the EGRET Instrument

The diffuse extragalactic gamma-ray background (EGRB) has been derived by various groups from observations by the Energetic Gamma Ray Experiment Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). The derived EGRB…

Astrophysics · Physics 2007-06-05 T. A. Porter , W. B. Atwood , B. Baughman , R. P. Johnson

A Search for Pulsars between 0.3 and 8 MeV using INTEGRAL

The spectra of only a few pulsars are known in the low-energy gamma-ray region around 1 Mev. We searched for point sources of gamma-radiation in the 0.3-1 and 1-8 Mev bandpasses at the location of known radio and X-ray pulsars. Single…

High Energy Astrophysical Phenomena · Physics 2011-04-21 Joseph F. Dolan

The Case for a Low Extragalactic Gamma-ray Background

Measurements of the diffuse extragalactic gamma-ray background (EGRB) are complicated by a strong Galactic foreground. Estimates of the EGRB flux and spectrum, obtained by modeling the Galactic emission, have produced a variety of…

Astrophysics · Physics 2009-11-10 Uri Keshet , Eli Waxman , Abraham Loeb

High-energy gamma-ray Emission from Microquasars: LS 5039 and LS I +61 303

The possible associations between the microquasars LS 5039 and LS I +61 303 and the EGRET sources 3EG J1824-1514 and 3EG J0241+6103 suggest that microquasars could also be sources of high-energy gamma-rays. In this work, we present a…

Astrophysics · Physics 2014-10-13 V. Bosch-Ramon , J. M. Paredes

Very high energy gamma-ray follow-up observations of novae and dwarf novae with the MAGIC telescopes

In the last few years the Fermi-LAT instrument has detected GeV gamma-ray emission from several novae. Such GeV emission can be interpreted in terms of inverse Compton emission from electrons accelerated in the shock or in terms of emission…

High Energy Astrophysical Phenomena · Physics 2019-08-15 R. López-Coto , J. Sitarek , W. Bednarek , E. de Ona Wilhelmi , R. Desiante , F. Longo , E. Hays

A New Method to Study the Origin of the EGB and the First Application on AT20G

In this letter, we introduce a new method of image stacking to directly study the undetected but possible gamma-ray point sources. Applying the method to the Australia Telescope 20 GHz Survey (AT20G) sources which have not been detected by…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Ming Zhou , Jiancheng Wang , Xiaoyan Gao

Cygnus X-3: A variable petaelectronvolt gamma-ray source

We report the discovery of variable $\gamma$-rays up to petaelectronvolt from Cygnus X-3, an iconic X-ray binary. The $\gamma$-ray signal was detected with a statistical significance of approximately 10 $\sigma$ by the Large High Altitude…

High Energy Astrophysical Phenomena · Physics 2026-04-14 The LHAASO Collaboration , Zhen Cao , F. Aharonian , Y. X. Bai , Y. W. Bao , D. Bastieri , X. J. Bi , Y. J. Bi , W. Bian , J. Blunier , A. V. Bukevich , C. M. Cai , Y. Y. Cai , W. Y. Cao , Zhe Cao , J. Chang , J. F. Chang , E. S. Chen , G. H. Chen , H. K. Chen , L. F. Chen , Liang Chen , Long Chen , M. J. Chen , M. L. Chen , Q. H. Chen , S. Chen , S. H. Chen , S. Z. Chen , T. L. Chen , X. B. Chen , X. J. Chen , X. P. Chen , Y. Chen , N. Cheng , Q. Y. Cheng , Y. D. Cheng , M. Y. Cui , S. W. Cui , X. H. Cui , Y. D. Cui , B. Z. Dai , H. L. Dai , Z. G. Dai , Danzengluobu , Y. X. Diao , A. J. Dong , X. Q. Dong , K. K. Duan , J. H. Fan , Y. Z. Fan , J. Fang , J. H. Fang , K. Fang , C. F. Feng , H. Feng , L. Feng , S. H. Feng , X. T. Feng , Y. Feng , Y. L. Feng , S. Gabici , B. Gao , Q. Gao , W. Gao , W. K. Gao , M. M. Ge , T. T. Ge , L. S. Geng , G. Giacinti , G. H. Gong , Q. B. Gou , M. H. Gu , F. L. Guo , J. Guo , K. J. Guo , X. L. Guo , Y. Q. Guo , Y. Y. Guo , R. P. Han , O. A. Hannuksela , M. Hasan , H. H. He , H. N. He , J. Y. He , X. Y. He , Y. He , S. Hernández-Cadena , B. W. Hou , C. Hou , X. Hou , H. B. Hu , S. C. Hu , C. Huang , D. H. Huang , J. J. Huang , X. L. Huang , X. T. Huang , X. Y. Huang , Y. Huang , Y. Y. Huang , A. Inventar , X. L. Ji , H. Y. Jia , K. Jia , H. B. Jiang , K. Jiang , X. W. Jiang , Z. J. Jiang , M. Jin , S. Kaci , M. M. Kang , I. Karpikov , D. Khangulyan , D. Kuleshov , K. Kurinov , Cheng Li , Cong Li , D. Li , F. Li , H. B. Li , H. C. Li , Jian Li , Jie Li , K. Li , L. Li , R. L. Li , S. D. Li , T. Y. Li , W. L. Li , X. R. Li , Xin Li , Y. Li , Zhe Li , Zhuo Li , E. W. Liang , Y. F. Liang , S. J. Lin , B. Liu , C. Liu , D. Liu , D. B. Liu , H. Liu , J. Liu , J. L. Liu , J. R. Liu , M. Y. Liu , R. Y. Liu , S. M. Liu , W. Liu , X. Liu , Y. Liu , Y. Liu , Y. N. Liu , Y. Q. Lou , Q. Luo , Y. Luo , H. K. Lv , B. Q. Ma , L. L. Ma , X. H. Ma , I. O. Maliy , J. R. Mao , Z. Min , W. Mitthumsiri , Y. Mizuno , G. B. Mou , A. Neronov , K. C. Y. Ng , M. Y. Ni , L. Nie , L. J. Ou , Z. W. Ou , P. Pattarakijwanich , Z. Y. Pei , D. Y. Peng , J. C. Qi , M. Y. Qi , J. J. Qin , D. Qu , A. Raza , C. Y. Ren , D. Ruffolo , A. Sáiz , D. Savchenko , D. Semikoz , L. Shao , O. Shchegolev , Y. Z. Shen , X. D. Sheng , Z. D. Shi , F. W. Shu , H. C. Song , Yu. V. Stenkin , V. Stepanov , Y. Su , D. X. Sun , H. Sun , J. X. Sun , Q. N. Sun , X. N. Sun , Z. B. Sun , N. H. Tabasam , J. Takata , P. H. T. Tam , H. B. Tan , Q. W. Tang , R. Tang , Z. B. Tang , W. W. Tian , C. N. Tong , L. H. Wan , C. Wang , D. H. Wang , G. W. Wang , H. G. Wang , J. C. Wang , K. Wang , Kai Wang , Kai Wang , L. P. Wang , L. Y. Wang , L. Y. Wang , R. Wang , W. Wang , X. G. Wang , X. J. Wang , X. Y. Wang , Y. Wang , Y. D. Wang , Z. H. Wang , Z. X. Wang , Zheng Wang , D. M. Wei , J. J. Wei , Y. J. Wei , T. Wen , S. S. Weng , C. Y. Wu , H. R. Wu , Q. W. Wu , S. Wu , X. F. Wu , Y. S. Wu , S. Q. Xi , J. Xia , J. J. Xia , G. M. Xiang , D. X. Xiao , G. Xiao , Y. F. Xiao , Y. L. Xin , H. D. Xing , Y. Xing , D. R. Xiong , B. N. Xu , C. Y. Xu , D. L. Xu , R. F. Xu , R. X. Xu , S. S. Xu , W. L. Xu , L. Xue , D. H. Yan , T. Yan , C. W. Yang , C. Y. Yang , F. F. Yang , L. L. Yang , M. J. Yang , R. Z. Yang , W. X. Yang , Z. H. Yang , Z. G. Yao , X. A. Ye , L. Q. Yin , N. Yin , X. H. You , Z. Y. You , Q. Yuan , H. Yue , H. D. Zeng , T. X. Zeng , W. Zeng , X. T. Zeng , M. Zha , B. B. Zhang , B. T. Zhang , C. Zhang , H. Zhang , H. M. Zhang , H. Y. Zhang , J. L. Zhang , J. Y. Zhang , Li Zhang , P. F. Zhang , R. Zhang , S. R. Zhang , S. S. Zhang , S. Y. Zhang , W. Zhang , W. Y. Zhang , X. Zhang , X. P. Zhang , Yi Zhang , Yong Zhang , Z. P. Zhang , J. Zhao , L. Zhao , L. Z. Zhao , S. P. Zhao , X. H. Zhao , Z. H. Zhao , F. Zheng , T. C. Zheng , B. Zhou , H. Zhou , J. N. Zhou , M. Zhou , P. Zhou , R. Zhou , X. X. Zhou , X. X. Zhou , B. Y. Zhu , C. G. Zhu , F. R. Zhu , H. Zhu , K. J. Zhu , Y. C. Zou , X. Zuo , J. S. Wang

The energy spectrum of cosmic-ray electrons at TeV energies

The very large collection area of ground-based gamma-ray telescopes gives them a substantial advantage over balloon/satellite based instruments in the detection of very-high-energy (>600 GeV) cosmic-ray electrons. Here we present the…

Astrophysics · Physics 2012-08-27 H. E. S. S. Collaboration , : , F. Aharonian

The Effect of Blazar Spectral Breaks on the Blazar Contribution to the Extragalactic Gamma-ray Background

The spectral shapes of the contributions of different classes of unresolved gamma-ray emitters can provide insight into their relative contributions to the extragalactic gamma-ray background (EGB) and the natures of their spectra at GeV…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Tonia M. Venters , Vasiliki Pavlidou

An AGN Identification for 3EG J2006-2321

We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321. The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of…

Astrophysics · Physics 2009-11-07 P. M. Wallace , J. P. Halpern , A. M. Magalhaes , D. J. Thompson

Cutoff in the hard X-ray spectra of the ultraluminous X-ray sources HoIX X-1 and M82 X-1

Using data from the XMM-Newton and INTEGRAL observatories, we have detected a cutoff at energies above 10 keV in the X-ray spectra of the ultraluminous X-ray sources HoIX X-1 and M82 X-1. The spectra obtained can be described by a model of…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Sergey Sazonov , Alexander Lutovinov , Roman Krivonos