0620022

Relativistic particle acceleration takes place in colliding-wind binaries thus leading to the emission of soft gamma-rays through inverse Compton scattering. Such a non-thermal emission has been recently detected for the ?rst time in Eta Carinae by INTEGRAL. The averaged emission from Eta Carinae in the 22?100 keV energy range is very hard (photon index around 1) and its luminosity is 7E33 erg/s. The X-ray emission of Eta Carinae is changing along its orbital period of 5.53 yr and there are hints that the same might apply to its gamma-ray emission. Therefore we propose to perform a 1 Ms observation of Eta Carinae around December 2008 during the next periastron passage. [truncated! Please see actual data for full text]