INTEGRAL observations of the PSR B1259-63 / SS2883 system after the 2004 periastron passage

Abstract

The millisecond pulsar PSR B1259-63 and the Be star SS2883 are situated in a highly eccentric binary system, with orbital period ~3.4 years. We report on hard X-ray observations obtained with the INTEGRAL satellite close to the 2004 periastron passage. These are the first imaging observations of this system in the hard X-ray range (>20 keV) and allow the emission of PSR B1259-63 to be separated from that of a nearby unidentified variable source which may have contaminated previous hard X-ray observations of this system. Using the IBIS/ISGRI instrument we measured a flux of ~2--6 mCrab in the 20--200 keV range, with a power law spectrum of photon index of 1.3 +/- 0.5.