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, The VERITAS Collaboration

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The very high energy (VHE; E> 100 GeV) blazar Markarian 501 was observed between April 17 and May 5 (MJD 54 938-54 956), 2009, as part of an extensive multi-wavelength campaign from radio to VHE. Strong VHE γ-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 × 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 15°. 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.

Original languageEnglish (US)
Article numberA76
JournalAstronomy and Astrophysics
Volume594
DOIs
StatePublished - Oct 1 2016

Bibliographical note

Publisher Copyright:
© 2016 ESO.

Keywords

  • BL Lacertae objects: individual: Mrk 501
  • Gamma rays: galaxies

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