Very High Energy outburst of Markarian 501 in May 2009

E. Aliu , S. Archambault , A. Archer , T. Arlen , T. Aune , A. Barnacka , B. Behera , M. Beilicke , W. Benbow , K. Berger , R. Bird , M. Böttcher , A. Bouvier , M. Buchovecky , J.H. Buckley , V. Bugaev , J.V. Cardenzana , M. Cerruti , A. Cesarini , X. Chen , L. Ciupik , E. Collins-Hughes , M.P. Connolly , W. Cui , J. Dumm , J.D. Eisch , A. Falcone , S. Federici , Q. Feng , J.P. Finley , H. Fleischhack , P. Fortin , L. Fortson , A. Furniss , N. Galante , D. Gall , G.H. Gillanders , S. Griffin , S.T. Griffiths , J. Grube , G. Gyuk , M. Hütten , N. Håkansson , J. Holder , G. Hughes , T.B. Humensky , C.A. Johnson , P. Kaaret , P. Kar , N. Kelley-Hoskins , M. Kertzman , Y. Khassen , D. Kieda , M. Krause , H. Krawczynski , F. Krennrich , M.J. Lang , A.S. Madhavan , G. Maier , S. Mcarthur , A. Mccann , K. Meagher , J. Millis , P. Moriarty , R. Mukherjee , D. Nieto , A. O'Faoláin de Bhróithe , R.A. Ong , M. Orr , A.N. Otte , D. Pandel , N. Park , V. Pelassa , J.S. Perkins , A. Pichel , M. Pohl , A. Popkow , J. Quinn , K. Ragan , L.C. Reyes , P.T. Reynolds , E. Roache , J. Rousselle , A.C. Rovero , D.B. Saxon , G.H. Sembroski , K. Shahinyan , F. Sheidaei , C. Skole , A.W. Smith , D. Staszak , I. Telezhinsky , M. Theiling , N.W. Todd , J.V. Tucci , J. Tyler , A. Varlotta , V.V. Vassiliev , S. Vincent , S.P. Wakely , O.M. Weiner , A. Weinstein , R. Welsing , A. Wilhelm , D.A. Williams , B. Zitzer , M.G. Baring , J. Becerra Gónzalez , A.N. Cillis , D. Horan (1) , D. Paneque

1 LLR - Laboratoire Leprince-Ringuet

The very high energy (VHE; E> 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54938-54956), 2009, as part of an extensive multi-wavelength campaign from radio to VHE. Strong VHE gamma-ray activity was detected on May 1st with Whipple and VERITAS, when the flux (E> 400 GeV) increased to 10 times the pre-flare baseline flux (3.9 x 10^-11 ph cm^-2 s^-1), reaching five times the flux of the Crab Nebula. This coincided with a decrease in the optical polarization and a rotation of the polarization angle by 15deg.. This VHE flare showed a fast flux variation with an increase of a factor ~4 in 25 min, and a falling time of ~50 min. We present the observations of the quiescent state previous to the flare and of the high state after the flare, focusing on the flux and spectral variability from Whipple, VERITAS, Fermi-LAT, RXTE, and Swift combined with optical and radio data.

Mots clés: BL Lacertae objects: individual: Mrk 501; gamma rays: galaxies; polarization: optical; polarization: rotation; gamma ray: flux; VERITAS; gamma ray: VHE; spectral; blazar; GLAST

Domaines: Astrophysique [astro-ph]

E. Aliu, S. Archambault, A. Archer, T. Arlen, T. Aune, et al.. Very High Energy outburst of Markarian 501 in May 2009. Astronomy and Astrophysics - A&A, 2016, 594, pp.A76. ⟨10.1051/0004-6361/201628744⟩. ⟨hal-01553871⟩