VERITAS Observations of the γ-Ray Binary LS I +61 303

/ Authors

V. Acciari, M. Beilicke, G. Blaylock, S. Bradbury, J. Buckley, V. Bugaev, Y. Butt, K. Byrum, O. Celik, A. Cesarini

and 67 more authors

L. Ciupik, Y. Chow, P. Cogan, P. Colin, W. Cui, M. Daniel, C. Duke, T. Ergin, A. Falcone, S. Fegan, J. Finley, P. Fortin, L. Fortson, D. Gall, K. Gibbs, G. Gillanders, J. Guenette, D. Hanna, E. Hays, J. Holder, D. Horan, S. Hughes, C. Hui, T. Humensky, P. Kaaret, D. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. Lang, S. LeBohec, K. Lee, G. Maier, A. McCann, M. McCutcheon, J. Millis, P. Moriarty, R. Mukherjee, T. Nagai, R. Ong, D. Pandel, J. Perkins, F. Pizlo, M. Pohl, J. Quinn, K. Ragan, P. Reynolds, H. Rose, M. Schroedter, G. Sembroski, A. Smith, D. Steele, S. Swordy, J. Toner, L. Valcárcel, V. Vassiliev, R. Wagner, S. Wakely, J. Ward, T. Weekes, A. Weinstein, R. White, D. Williams, S. Wissel, M. Wood, B. Zitzer

/ Abstract

LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy γ-rays. The system was observed over several orbital cycles (between 2006 September and 2007 February) with the VERITAS array of imaging air Cerenkov telescopes. A signal of γ-rays with energies above 300 GeV is found with a statistical significance of 8.4 standard deviations. The detected flux is measured to be strongly variable; the maximum flux is found during most orbital cycles at apastron. The energy spectrum for the period of maximum emission can be characterized by a power law with a photon index of Γ = 2.40 ± 0.16stat± 0.2sys and a flux above 300 GeV corresponding to 15%-20% of the flux from the Crab Nebula.

Journal: The Astrophysical Journal

DOI: 10.1086/587736

VERITAS Observations of the γ-Ray Binary LS I +61 303

/ Authors

V. Acciari, M. Beilicke, G. Blaylock, S. Bradbury, J. Buckley, V. Bugaev, Y. Butt, K. Byrum, O. Celik, A. Cesarini

and 67 more authors

/ Abstract

Journal: The Astrophysical Journal

DOI: 10.1086/587736