Veritas observations of day-scale flaring of M 87 in 2010 April

E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, C. Duke, M. Errando, A. FalconeJ. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, S. Lebohec, A. S. Madhavan, G. Maier, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, P. D. Nũez, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, A. Pichel, M. Pohl, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Entürk, C. Skole, D. Staszak, G. Teić, M. Theiling, S. Thibadeau, K. Tsurusaki, J. Tyler, A. Varlotta, V. V. Vassiliev, S. Vincent, M. Vivier, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, B. Zitzer

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 ± 0.16) × 10-11 cm-2 s-1 at energies above 350GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 ± 0.68) × 10-11 cm-2 s-1 for E > 350GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90+0.22 -0.15days. The shortest detected exponential rise time is three times as long, at 2.87 +1.65 -0.99days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 ± 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.

Original languageEnglish (US)
Article number141
JournalAstrophysical Journal
Volume746
Issue number2
DOIs
StatePublished - Feb 20 2012

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., ... Zitzer, B. (2012). Veritas observations of day-scale flaring of M 87 in 2010 April. Astrophysical Journal, 746(2), [141]. https://doi.org/10.1088/0004-637X/746/2/141