Observation of gamma-ray emission from the galaxy M87 above 250 GeV with VERITAS

Acciari, V.; Beilicke, M.; Blaylock, G.; Bradbury, S.; Buckley, J.; Bugaev, V.; Butt, Y.; Celik, O.; Cesarini, A.; Ciupik, L.; Cogan, P.; Colin, P.; Cui, W.; Daniel, M.; Duke, C.; Ergin, TÜLÜN; Falcone, A.; Fegan, S.; Finley, J.; Finnegan, G.; Fortin, P.; Fortson, L.; Gibbs, K.; Gillanders, G.; Grube, J.; Guenette, R.; Gyuk, G.; Hanna, D.; Hays, E.; Holder, J.; Horan, D.; Hughes, S.; Hui, M.; Humensky, T.; Imran, A.; Kaaret, P.; Kertzman, M.; Kieda, D.; Kildea, J.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M.; LeBohec, S.; Lee, K.; Maier, G.; McCann, A.; McCutcheon, M.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nagai, T.; Ong, R.; Pandel, D.; Perkins, J.; Pohl, M.; Quinn, J.; Ragan, K.; Reynolds, P.; Rose, H.; Schroedter, M.; Sembroski, G.; Smith, A.; Steele, D.; Swordy, S.; Syson, A.; Toner, J.; Valcarcel, L.; Vassiliev, V.; Wakely, S.; Ward, J.; Weekes, T.; Weinstein, A.; White, R.; Williams, D.; Wissel, S.; Wood, M.; Zitzer, B.

doi:10.1086/587458

Observation of gamma-ray emission from the galaxy M87 above 250 GeV with VERITAS

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Acciari V. A., Beilicke M., Blaylock G., Bradbury S. M., Buckley J. H., Bugaev V., ...More

ASTROPHYSICAL JOURNAL, vol.679, no.1, pp.397-403, 2008 (SCI-Expanded)

Publication Type: Article / Article
Volume: 679 Issue: 1
Publication Date: 2008
Doi Number: 10.1086/587458
Journal Name: ASTROPHYSICAL JOURNAL
Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
Page Numbers: pp.397-403
Keywords: galaxies : individual (M87, NGC 4486, Virgo A), gamma rays : observations, SUPERMASSIVE BLACK-HOLE, X-RAY, TELESCOPE OBSERVATIONS, UNIFIED SCHEMES, TEV EMISSION, LAC OBJECTS, CRAB-NEBULA, JET, MARKARIAN-421, VARIABILITY
Middle East Technical University Affiliated: Yes

Abstract

The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in active galactic nuclei from radio waves to TeV gamma-rays. Here we report the detection of gamma-ray emission above 250 GeV from M87 in spring 2007 with the VERITAS atmospheric Cerenkov telescope array and discuss its correlation with the X-ray emission. The gamma-ray emission is measured to be pointlike with an intrinsic source radius less than 4.5'. The differential energy spectrum is fitted well by a power-law function: d Phi/dE = (7.4 +/- 1.3(stat) +/- 1.5(sys))(E/TeV)((-2.31 +/- 0.17stat +/- 0.2sys)) 10(-9) m(-2) s(-1) TeV(-1). We show strong evidence for a year-scale correlation between the gamma-ray flux reported by TeV experiments and the X-ray emission measured by the ASM RXTE observatory, and discuss the possible short-timescale variability. These results imply that the gamma-ray emission from M87 is more likely associated with the core of the galaxy than with other bright X-ray features in the jet.