Related papers: Evidence for a second component in the high-energy…

Measurement Of the Galactic X-ray/Gamma-ray Background Radiation: Contribution of Discrete Sources

The Galactic background radiation near the Scutum Arm was observed simultaneously with RXTE and OSSE in order to determine the spectral shape and the origin of the emission in the hard X-ray/soft gamma-ray band. The spectrum in the 3 keV to…

Astrophysics · Physics 2009-10-31 Azita Valinia , Robert L. Kinzer , Francis E. Marshall

Evidence for TeV gamma ray emission from Cassiopeia A

232 hours of data were accumulated from 1997 to 1999, using the HEGRA Stereoscopic Cherenkov Telescope System to observe the supernova remnant Cassiopeia A. TeV gamma ray emission was detected at the 5 sigma level, and a flux of (5.8 +-…

Astrophysics · Physics 2011-05-05 HEGRA Collaboration , F. Aharonian

Diffuse gamma-ray emission: Galactic and extragalactic

Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…

Astrophysics · Physics 2007-05-23 Martin Pohl

Distributed accelerators in the jet of Centaurus A: the origin of the spectral hardening of very high energy gamma-rays

We propose the synchrotron self-Compton (SSC) scenario coupled with filamentary jet model, to reproduce the very high energy $\gamma$-ray emissions from Cen A. With reference to self-similarity of knot-like features in the jet, we assume…

High Energy Astrophysical Phenomena · Physics 2026-03-24 Y. S. Honda , M. Honda

The Electron Energy Distribution in the Hotspots of Cygnus A: Filling the Gap with the Spitzer Space Telescope

Here we present Spitzer Space Telescope imaging of Cyg A with the Infrared Array Camera, resulting in the detection of the high-energy tails or cut-offs in the synchrotron spectra for all four hotspots of this archetype radio galaxy. When…

Astrophysics · Physics 2011-02-11 L. Stawarz , C. C. Cheung , D. E. Harris , M. Ostrowski

Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A

Observations of the FR I radio galaxy Centaurus A in radio, X-ray and gamma-ray bands provide evidence for lepton acceleration up to several TeV and clues about hadron acceleration to tens of EeV. Synthesising the available observational…

High Energy Astrophysical Phenomena · Physics 2013-10-01 Sarka Wykes , Judith H. Croston , Martin J. Hardcastle , Jean A. Eilek , Peter L. Biermann , Abraham Achterberg , Justin D. Bray , Alex Lazarian , Marijke Haverkorn , Ray J. Protheroe , Omer Bromberg

ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and Timing

We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by \asca. The imaging data reveal a number of serendipitous hard X-ray sources in some source fields, but…

Astrophysics · Physics 2008-11-26 K. Nandra , I. M. George , R. F. Mushotzky , T. J. Turner , T. Yaqoob

A Chandra X-ray Study of Cygnus A - II. The Nucleus

We report Chandra ACIS and quasi-simultaneous RXTE observations of the nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the properties of the active nucleus. In the Chandra observation, the hard (> a few keV) X-ray…

Astrophysics · Physics 2009-11-07 Andrew J. Young , Andrew S. Wilson , Yuichi Terashima , Keith A. Arnaud , David A. Smith

Broadband $\gamma$-ray spectrum of supernova remnant Cassiopeia A

The core-collapse supernova remnant (SNR) Cassiopeia A (Cas A) is one of the brightest galactic radio sources with an angular radius of $\sim$ 2.5 $\arcmin$. Although no extension of this source has been detected in the $\gamma$-ray band,…

High Energy Astrophysical Phenomena · Physics 2025-02-10 Zhen Cao , F. Aharonian , Y. X. Bai , Y. W. Bao , D. Bastieri , X. J. Bi , Y. J. Bi , W. Bian , A. V. Bukevich , C. M. Cai , W. Y. Cao , Zhe Cao , J. Chang , J. F. Chang , A. M. Chen , E. S. Chen , H. X. 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 , Y. Chen , N. Cheng , Y. D. Cheng , M. C. Chu , 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 , 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 , C. D. 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 , X. L. Guo , Y. Q. Guo , Y. Y. Guo , Y. A. Han , O. A. Hannuksela , M. Hasan , H. H. He , H. N. He , J. Y. He , X. Y. He , Y. He , S. Hernández-Cadena , Y. K. Hor , B. W. Hou , C. Hou , X. Hou , H. B. Hu , S. C. Hu , C. Huang , D. H. Huang , J. J. Huang , T. Q. Huang , W. J. Huang , X. T. Huang , X. Y. Huang , Y. Huang , Y. Y. Huang , 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 , B. B. Li , 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. Z. 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 , H. D. 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 , J. R. Mao , Z. Min , W. Mitthumsiri , G. B. Mou , H. J. Mu , Y. C. Nan , A. Neronov , K. C. Y. Ng , M. Y. Ni , L. Nie , L. J. Ou , P. Pattarakijwanich , Z. Y. Pei , J. C. Qi , M. Y. Qi , J. J. Qin , A. Raza , C. Y. Ren , D. Ruffolo , A. Sáiz , M. Saeed , 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 , 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 , G. W. Wang , H. G. Wang , H. H. 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. L. Xin , Y. Xing , D. R. Xiong , Z. Xiong , D. L. Xu , R. F. Xu , R. X. Xu , W. L. Xu , L. Xue , D. H. Yan , J. Z. Yan , T. Yan , C. W. Yang , C. Y. Yang , F. F. Yang , L. L. Yang , M. J. Yang , R. Z. Yang , W. X. Yang , Y. H. Yao , Z. G. Yao , X. A. Ye , L. Q. Yin , N. Yin , X. H. You , Z. Y. You , Y. H. Yu , Q. Yuan , H. Yue , H. D. Zeng , T. X. Zeng , W. Zeng , M. Zha , B. B. Zhang , B. T. Zhang , F. Zhang , H. Zhang , H. M. Zhang , H. Y. Zhang , J. L. Zhang , Li Zhang , P. F. Zhang , P. P. Zhang , R. Zhang , S. R. Zhang , S. S. 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 , W. J. Zhong , 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

A Possible Common Physic Picture Reflected by the Gamma Ray Emission of the Galactic Center

Long-term observations of the Galactic center by Fermi and HESS have revealed a novel phenomenon: the high-energy gamma-ray spectrum from the Galactic center exhibits a double power-law structure. In this study, we propose a new explanation…

High Energy Astrophysical Phenomena · Physics 2025-03-10 Lin Nie , Yi-Qing Guo , Si-Ming Liu

Interpretation of the unprecedentedly long-lived high-energy emission of GRB 130427A

High energy photons (>100 MeV) are detected by the Fermi/LAT from GRB 130427A up to almost one day after the burst, with an extra hard spectral component being discovered in the high-energy afterglow. We show that this hard spectral…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Ruo-Yu Liu , Xiang-Yu Wang , Xue-Feng Wu

Discovery of hard X-ray features around hotspots of Cygnus A

We present results of analysis of a Chandra observation of Cygnus A in which the X-ray hotspots at the ends of the jets are mapped in detail. A hardness map reveals previously unknown structure in the form of outer and inner hard arcs…

Astrophysics · Physics 2009-11-10 M. Balucinska-Church , M. Ostrowski , L. Stawarz , M. J. Church

High-energy Emission Processes in M 87

We study the contribution of thermal and non-thermal processes to the inverse Compton emission of the radio galaxy M 87 by modelling its broad-band emission. Through this we aim to derive insight into where within the AGN the X-ray,…

High Energy Astrophysical Phenomena · Physics 2015-04-27 S. de Jong , V. Beckmann , S. Soldi , A. Tramacere , A. Gros

Sgr A* Observations with H.E.S.S. II

The Galactic Centre has been studied with the High Energy Stereoscopic System (H.E.S.S.) for over 10 years, revealing a bright, complex gamma-ray morphology. Besides a strong point-like very-high-energy gamma-ray source coincident with the…

High Energy Astrophysical Phenomena · Physics 2019-08-14 R. D. Parsons , M. Holler , J. King , V. Lefranc , E. Moulin , H. Poon , J. Veh , A. Viana

Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported.…

High Energy Astrophysical Phenomena · Physics 2022-09-07 O. Adriani , Y. Akaike , K. Asano , Y. Asaoka , E. Berti , G. Bigongiari , W. R. Binns , M. Bongi , P. Brogi , A. Bruno , J. H. Buckley , N. Cannady , G. Castellini , C. Checchia , M. L. Cherry , G. Collazuol , K. Ebisawa , A. W. Ficklin , H. Fuke , S. Gonzi , T. G. Guzik , T. Hams , K. Hibino , M. Ichimura , K. Ioka , W. Ishizaki , M. H. Israel , K. Kasahara , J. Kataoka , R. Kataoka , Y. Katayose , C. Kato , N. Kawanaka , Y. Kawakubo , K. Kobayashi , K. Kohri , H. S. Krawczynski , J. F. Krizmanic , P. Maestro , P. S. Marrocchesi , A. M. Messineo , J. W. Mitchell , S. Miyake , A. A. Moiseev , M. Mori , N. Mori , H. M. Motz , K. Munakata , S. Nakahira , J. Nishimura , G. A. de Nolfo , S. Okuno , J. F. Ormes , S. Ozawa , L. Pacini , P. Papini , B. F. Rauch , S. B. Ricciarini , K. Sakai , T. Sakamoto , M. Sasaki , Y. Shimizu , A. Shiomi , P. Spillantini , F. Stolzi , S. Sugita , A. Sulaj , M. Takita , T. Tamura , T. Terasawa , S. Torii , Y. Tsunesada , Y. Uchihori , E. Vannuccini , J. P. Wefel , K. Yamaoka , S. Yanagita , A. Yoshida , K. Yoshida , W. V. Zober

Origin of the Proton-to-Helium Ratio Anomaly in Cosmic Rays

Recent data on Galactic cosmic rays (CRs) revealed that the helium energy spectrum is harder than the proton spectrum. The AMS experiment has now reported that the proton-to-helium ratio as function of rigidity $R$ (momentum-to-charge…

High Energy Astrophysical Phenomena · Physics 2015-12-04 Nicola Tomassetti

High Energy Break and Reflection Features in the Seyfert Galaxy MCG+8-11-11

We present the results from ASCA and OSSE simultaneous observations of the Seyfert 1.5 galaxy MCG+8-11-11 performed in August-September 1995. The ASCA observations indicate a modest flux increase (20%) in 3 days, possibly correlated to a…

Astrophysics · Physics 2009-10-30 P. Grandi , F. Haardt , G. Ghisellini , E. J. Grove , L. Maraschi , C. M. Urry

A multi-faceted view of the X-ray spectral variability in Seyfert galaxy Ark 120

Utilizing a range of techniques including multi-band light curves, softness ratio analysis, structure functions, rms spectra, cross-correlation functions, and ratios of spectra from different intervals, we present a comprehensive study of…

High Energy Astrophysical Phenomena · Physics 2024-10-31 Lu-Xin Ren , Jun-Xian Wang , Jia-Lai Kang

Energetics of High-Energy Cosmic Radiations

The luminosity densities of high-energy cosmic radiations are studied to find connections among the various components, including high-energy neutrinos measured with IceCube and gamma rays with the Fermi satellite. Matching the cosmic-ray…

High Energy Astrophysical Phenomena · Physics 2019-05-09 Kohta Murase , Masataka Fukugita

A Possible Link Between the Galactic Center HESS Source and Sgr A*

Recently, HESS and other air Cerenkov telescopes have detected a source of TeV gamma-rays coincident with the Galactic center. It is not yet clear whether the gamma-rays are produced via leptonic or hadronic processes, so it is important to…

Astrophysics · Physics 2009-11-13 D. R. Ballantyne , Fulvio Melia , Siming Liu , Roland M. Crocker