2010MNRAS.408..642Z

LS I +61°303 is one of the few high-mass X-ray binaries that has been recently observed at TeV and GeV energies. Here we investigate the hard X-ray spectral and timing properties of this source using the IBIS/ISGRI instrument on-board the INTEGRAL satellite. We carry out a systematic analysis based on all available INTEGRAL data since 2002 December 28 up to 2008 April 30. The total exposure time analysed amounts to 2.1Ms, hence more than double the previous reported sample. The source is best detected in the 18-60keV band, with a significance level of 12.0σ. The hard X-ray data are best fitted with a simple power law with a photon index of ∼1.7±0.2. We detect a periodical signal at 27±4d, matching the orbital period of 26.496d previously reported at other wavelengths. The hard X-ray orbital light curve is obtained and compared with those derived at other frequencies.