LONG-TERM MONITORING OF MRK 501 FOR ITS VERY HIGH ENERGYγ EMISSION AND A FLARE IN 2011 OCTOBER

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Abstract

As one of the brightest active blazars in both X-ray and very high energy γ-ray bands, Mrk 501, is very useful for physics associated with jets from active galactic nuclei. The ARGO-YBJ experiment has monitoredMrk 501 for γ-rays above 0.3 TeV since 2007 November. The largest flare since 2005 was observed from 2011 October and lasted until about 2012 April. In this paper, a detailed analysis of this event is reported. During the brightest γ-ray flaring episodes from 2011 October 17 to November 22, an excess of the event rate over 6σ is detected by ARGO-YBJ in the direction of Mrk 501, corresponding to an increase of the γ -ray flux above 1 TeV by a factor of 6.6 ± 2.2 from its steady emission. In particular, the γ -ray flux above 8 TeV is detected with a significance better than 4σ. Based on time-dependent synchrotron self-Compton (SSC) processes, the broadband energy spectrum is interpreted as the emission from an electron energy distribution parameterized with a single power-law function with an exponential cutoff at its high-energy end. The average spectral energy distribution for the steady emission is well described by this simple one-zone SSC model. However, the detection of γ -rays above 8 TeV during the flare challenges this model due to the hardness of the spectra. Correlations between X-rays and γ -rays are also investigated.

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  • B. Bartoli , P. Bernardini , X. J. Bi , C. Bleve , I. Bolognino , P. Branchini , A. Budano , A. K. Calabrese Melcarne , P. Camarri , Z. Cao , R. Cardarelli , S. Catalanotti , C. Cattaneo , S.Z. Chen , T.L. Chen , Y. Chen , P. Creti , S. W. Cui , B.Z. Dai , G. D’Al´ı Staiti , Danzengluobu , M. Dattoli , I. De Mitri , B. D’Ettorre Piazzoli , T. Di Girolamo , X.H. Ding , G. Di Sciascio , C.F. Feng , Zhaoyang Feng , Zhenyong Feng , F. Galeazzi , E. Giroletti , Q.B. Gou , Y.Q. Guo , H.H. He , Haibing Hu , Hongbo Hu , Q. Huang , M. Iacovacci , R. Iuppa , I. James , H.Y. Jia , Labaciren , H.J. Li , J.Y. Li , X.X. Li , G. Liguori , C. Liu , C.Q. Liu , J. Liu , M. Y. Liu , H. Lu , L.L. Ma , X.H. Ma , G. Mancarella , S. M. Mari , G. Marsella , D. Martello , S. Mastroianni , P. Montini , C.C. Ning , A. Pagliaro , M. Panareo , B. Panico , L. Perrone , P. Pistilli , F. Ruggieri , P. Salvini , R. Santonico , P.R. Shen , X.D. Sheng , F. Shi , C. Stanescu , A. Surdo , Y.H. Tan , P. Vallania , S. Vernetto , C. Vigorito , B. Wang , H. Wang , C. Y. Wu , H.R. Wu , B. Xu , L. Xue , Q.Y. Yang , X.C. Yang , Z.G. Yao , A.F. Yuan , M. Zha , H. M. Zhang , Jilong Zhang , Jianli Zhang , L. Zhang , P. Zhang , X.Y. Zhang , Y. Zhang , J. Zhao , Zhaxiciren , Zhaxisangzhu , X.X. Zhou , F.R. Zhu , Q.Q. Zhu , G. Zizzi

Titolo volume/Rivista

THE ASTROPHYSICAL JOURNAL

Anno di pubblicazione

2012

ISSN

0004-637X

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

30

Ultimo Aggiornamento Citazioni

28/04/2018

Settori ERC

Non Disponibile

Codici ASJC

Non Disponibile