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Is Supernova Remnant Cassiopeia A a PeVatron?

Cassiopeia A, a well-observed young core-collapse supernova remnant (SNR), is considered as one of the best candidates for studying very high-energy particle acceleration up to PeV via the diffusive shock mechanism. Recently, MAGIC…

High Energy Astrophysical Phenomena · Physics 2019-04-03 Xiao Zhang , Siming Liu

Deep observations of Cas A with MAGIC indicate it is no PeVatron

It is widely believed that Galactic Cosmic Rays (CR) are accelerated in Supernova Remnants (SNRs) through the process of diffusive shock acceleration. In this scenario, particles should be accelerated up to energies around 1 PeV (the…

High Energy Astrophysical Phenomena · Physics 2019-08-15 D. Guberman , J. Cortina , E. de Oña Wilhelmi , D. Galindo , A. Moralejo

Particle Acceleration in Cassiopeia A Revealed by Broadband High-Energy Spectrum

Recently, the GeV--sub-PeV spectrum of supernova remnant (SNR) Cassiopeia A (Cas A), one of the youngest and most well-studied SNRs in our Galaxy, has been updated by observations of Fermi-LAT and LHAASO. We revisit Cas A with our previous…

High Energy Astrophysical Phenomena · Physics 2026-03-30 Bo-Tao Li , Wei Wang , Zhuo Li

Spectrum and location of ongoing extreme particle acceleration in Cassiopeia A

Young supernova remnants (SNRs) are believed to be the origin of energetic cosmic rays (CRs) below the "knee" of their spectrum at $\sim3$ petaelectronvolt (PeV, $10^{15}$ eV). Nevertheless, the precise location, duration, and operation of…

High Energy Astrophysical Phenomena · Physics 2024-11-28 Jooyun Woo , Kaya Mori , Charles J. Hailey , Elizabeth Spira-Savett , Aya Bamba , Brian W. Grefenstette , Thomas B. Humensky , Reshmi Mukherjee , Samar Safi-Harb , Tea Temim , Naomi Tsuji

A Deep Observation of Gamma-ray Emission from Cassiopeia A using VERITAS

Supernova remnants (SNRs) have long been considered the leading candidates for the accelerators of cosmic rays within the Galaxy through the process of diffusive shock acceleration. The connection between SNRs and cosmic rays is supported…

High Energy Astrophysical Phenomena · Physics 2019-08-17 Augusto Ghiotto

Ultra-high-energy $\gamma$-ray imprints from PeV particles accelerated by supernova remnants

The quest for the origin of cosmic ray (CRs) is a fundamental issue in astrophysics. Shocks of supernova remnants (SNRs) have been considered as the dominant contributors to Galactic CRs below the spectral knee near $\sim 3$…

High Energy Astrophysical Phenomena · Physics 2026-04-27 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 , 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 , 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 , Y. Li

The Hunt for Pevatrons: The Case of Supernova Remnants

The search for Galactic pevatrons is now a well-identified key science project of all instruments operating in the very-high-energy domain. Indeed, in this energy range, the detection of gamma rays clearly indicates that efficient particle…

High Energy Astrophysical Phenomena · Physics 2021-10-18 P. Cristofari

LHAASO J2108+5157 as a Molecular Cloud Illuminated by a Supernova Remnant

The search for Galactic PeVatrons - astrophysical accelerators of cosmic rays to PeV energies - has entered a new phase in recent years with the discovery of the first Ultra-High-Energy (UHE, $E>100$ TeV) gamma-ray sources by the HAWC and…

High Energy Astrophysical Phenomena · Physics 2023-10-30 A. M. W. Mitchell

A detailed study of Gamma-ray emission from Cassiopeia A using VERITAS

Supernova remnants (SNRs) have long been considered the leading candidate sites for the acceleration of cosmic rays within the Galaxy through the process of diffusive shock acceleration. The connection between SNRs and cosmic rays is…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Sajan Kumar

Multiwavelength Analysis of Galactic Supernova Remnants

The origin of Galactic Cosmic Rays (CRs) and the possibility of Supernova Remnants (SNRs) being potential CR accelerators is still an open debate. The charged CRs can be detected indirectly by the {\gamma}-ray observatories through the…

High Energy Astrophysical Phenomena · Physics 2023-04-21 Pooja Sharma , Ziwei Ou , Charles Henry-Cadrot , Coline Dubos , Tiina Suomijärvi

A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A

It is widely believed that the bulk of the Galactic cosmic rays are accelerated in supernova remnants (SNRs). However, no observational evidence of the presence of particles of PeV energies in SNRs has yet been found. The young historical…

High Energy Astrophysical Phenomena · Physics 2020-01-30 MAGIC Collaboration , M. L. Ahnen , S. Ansoldi , L. A. Antonelli , C. Arcaro , A. Babić , B. Banerjee , P. Bangale , U. Barres de Almeida , J. A. Barrio , J. Becerra González , W. Bednarek , E. Bernardini , A. Berti , W. Bhattacharyya , B. Biasuzzi , A. Biland , O. Blanch , S. Bonnefoy , G. Bonnoli , R. Carosi , A. Carosi , A. Chatterjee , S. M. Colak , P. Colin , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , P. Cumani , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , E. de Oña Wilhelmi , F. Di Pierro , M. Doert , A. Domínguez , D. Dominis Prester , D. Dorner , M. Doro , S. Einecke , D. Eisenacher Glawion , D. Elsaesser , M. Engelkemeier , V. Fallah Ramazani , A. Fernández-Barral , D. Fidalgo , M. V. Fonseca , L. Font , C. Fruck , D. Galindo , R. J. García López , M. Garczarczyk , M. Gaug , P. Giammaria , N. Godinović , D. Gora , D. Guberman , D. Hadasch , A. Hahn , T. Hassan , M. Hayashida , J. Herrera , J. Hose , D. Hrupec , T. Inada , K. Ishio , Y. Konno , H. Kubo , J. Kushida , D. Kuveždić , D. Lelas , E. Lindfors , S. Lombardi , F. Longo , M. López , C. Maggio , P. Majumdar , M. Makariev , G. Maneva , M. Manganaro , K. Mannheim , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , U. Menzel , M. Minev , R. Mirzoyan , A. Moralejo , V. Moreno , E. Moretti , V. Neustroev , A. Niedzwiecki , M. Nievas Rosillo , K. Nilsson , D. Ninci , K. Nishijima , K. Noda , L. Nogués , S. Paiano , J. Palacio , D. Paneque , R. Paoletti , J. M. Paredes , G. Pedaletti , M. Peresano , L. Perri , M. Persic , P. G. Prada Moroni , E. Prandini , I. Puljak , J. R. Garcia , I. Reichardt , W. Rhode , M. Ribó , J. Rico , C. Righi , T. Saito , K. Satalecka , S. Schroeder , T. Schweizer , S. N. Shore , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Stamerra , M. Strzys , T. Surić , L. Takalo , F. Tavecchio , P. Temnikov , T. Terzić , D. Tescaro , M. Teshima , N. Torres-Albà , A. Treves , G. Vanzo , M. Vazquez Acosta , I. Vovk , J. E. Ward , M. Will , D. Zarić

Gamma radiation from cosmic rays escaping a young supernova remnant: The case of Cas A

The escape of accelerated particles from supernova remnants remains one of the central and yet least understood aspects of the origin of cosmic rays. Here we use the results of the recent LHAASO observation of gamma rays from a region of…

High Energy Astrophysical Phenomena · Physics 2025-09-11 P. Blasi

A search for outstanding sources of PeV cosmic rays: Cassiopeia A, the Crab Nebula, the Monogem Ring--But how about M33 and the Virgo cluster?

We study arrival directions of 1.4x10^6 extensive air showers (EAS) registered with the EAS--1000 Prototype Array in the energy range 0.1--10 PeV. By applying an iterative algorithm that provides uniform distribution of the data with…

Astrophysics · Physics 2007-05-23 G. V. Kulikov , M. Yu. Zotov

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

The LHAASO PeVatron bright sky: what we learned

The recent detection of 12 gamma-ray Galactic sources well above E > 100 TeV by the LHAASO observatory has been a breakthrough in the context of Cosmic Ray (CR) origin search. Although most of these sources are unidentified, they are often…

High Energy Astrophysical Phenomena · Physics 2023-05-31 Martina Cardillo , Andrea Giuliani

Cosmic ray diffusion near the Bohm limit in the Cassiopeia A supernova remnant

Supernova remnants (SNRs) are believed to be the primary location of the acceleration of Galactic cosmic rays, via diffusive shock (Fermi) acceleration. Despite considerable theoretical work the precise details are still unknown, in part…

Astrophysics · Physics 2008-11-26 Michael D. Stage , Glenn E. Allen , John C. Houck , John E. Davis

Expectation on Observation of Supernova Remnants with the LHAASO Project

Supernova remnants (SNRs) are believed to be the most important acceleration sites for cosmic rays (CRs) below $\sim10^{15}$ eV in the Galaxy. High energy photons, either directly from the shocks of the SNRs or indirectly from the…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Ye Liu , Zhen Cao , Songzhan Chen , Yang Chen , Shuwang Cui , Huihai He , Xingtao Huang , Xinhua Ma , Qiang Yuan , Xiao Zhang

High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae

The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second knee ($\sim6\times10^{17}$eV) above in the CR spectrum is still unknown. Recently, there has been growing evidence that a peculiar type of supernovae, called…

Astrophysics · Physics 2008-12-18 Xiang-Yu Wang , Soebur Razzaque , Peter Meszaros , Zi-Gao Dai

What sources are the dominant Galactic cosmic-ray accelerators?

Supernova remnants (SNRs) have long been considered to be the dominant source of Galactic cosmic rays, which implied that they provided most of the energy to power cosmic rays as well as being PeVatrons. The lack of evidence for PeV cosmic…

High Energy Astrophysical Phenomena · Physics 2022-12-27 Jacco Vink

Revealing a peculiar supernova remnant G106.3+2.7 as a petaelectronvolt proton accelerator with X-ray observations

Supernova remnants (SNRs) have long been considered as one of the most promising sources of Galactic cosmic rays. In the SNR paradigm, petaelectronvolt (PeV) proton acceleration may only be feasible at the early evolution stage, lasting a…

High Energy Astrophysical Phenomena · Physics 2021-06-02 Chong Ge , Ruo-Yu Liu , Shu Niu , Yang Chen , Xiang-Yu Wang