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

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 September 2006 and February 2007) with the VERITAS array of imaging air-Cherenkov 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.

accepted for publication in The Astrophysical Journal

References in corpus (4)

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• Accretion vs colliding wind models for the gamma-ray binary LS I +61 303: an assessment
• Joint H-alpha and X-Ray Observations of Massive X-Ray Binaries. II. The Be X-ray Binary and Microquasar LS I +61 303
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Cited by in corpus (6)

• HESS J0632+057 : A new gamma-ray binary?
• Periodic very high energy gamma-ray emission from LS I +61 303 observed with the MAGIC telescope
• INTEGRAL observation of hard X-ray variability of the TeV binary LS5039 / RX J1826.2-1450
• Neutrino signal from gamma-ray loud binaries powered by high energy protons
• Status of Very High Energy gamma-ray Astronomy as of early 2008
• The MAGIC highlights of the gamma ray binary LS I +61 303