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.
Veritas observations of the gamma-ray binary LS I+61 303
Cesarini, Andrea;
2008-01-01
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione