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 gamma-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 gamma-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 Gamma = 2.40 +/- 0.16(stat) +/- 0.2(sys) and a flux above 300 GeV corresponding to 15% - 20% of the flux from the Crab Nebula.
Published in:
Astrophysical Journal 679,2 (2008) 1427-1432;
Link to original published article:
http://dx.doi.org/10.1086/587736
Keywords
acceleration of particles;; binaries : general;; gamma rays :;; observations;; stars : individual (LS I+61 303);; Astronomy & Astrophysics
Date of Version
January 2008
Recommended Citation
Acciari, V. A.; Beilicke, M.; Blaylock, G.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Butt, Y.; Byrum, K. L.; Celik, O.; Cesarini, A.; Ciupik, L.; Chow, Y. C. K.; Cogan, P.; Colin, P.; Cui, W.; Daniel, M. K.; Duke, C.; Ergin, T.; Falcone, A. D.; Fegan, S. J.; Finley, J. P.; Fortin, P.; Fortson, L. F.; Gall, D.; Gibbs, K.; Gillanders, G. H.; Grube, J.; Guenette, R.; Hanna, D.; Hays, E.; Holder, J.; Horan, D.; Hughes, S. B.; Hui, C. M.; Humensky, T. B.; Kaaret, P.; Kieda, D. B.; Kildea, J.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Lee, K.; Maier, G.; McCann, A.; McCutcheon, M.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nagai, T.; Ong, R. A.; Pandel, D.; Perkins, J. S.; Pizlo, F.; Pohl, M.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Smith, A. W.; Steele, D.; Swordy, S. P.; Toner, J. A.; Valcarcel, L.; Vassiliev, V. V.; Wagner, R.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A.; White, R. J.; Williams, D. A.; Wissel, S. A.; Wood, M.; and Zitzer, B., "Veritas observations of the gamma-ray binary LS I+61 303" (2008). Department of Physics and Astronomy Faculty Publications. Paper 639.
https://docs.lib.purdue.edu/physics_articles/639