Klaus Reitberger Innsbruck

A gamma-ray source at the position of Eta Carinae (pdf)

The colliding-wind binary Eta Carinae - one of the most remarkable objects in our Galaxy - is liable to be a source of high energetic gamma-rays. There are at least two different models which predict diffuse shock acceleration of charged particles and subsequent gamma-ray emission to occur at the position of Eta Car. One model (Reimer et al. 2006) predicts these processes to be active in the wind-collision region between the two components of the binary system, the other (S. Ohm et al. 2010) assumes particle acceleration to occur in the expanding blast wave originating in the "Great Eruption" of 1843. Recent observations by the high energy gamma-ray observatory FERMI-LAT confirm the existence of a source near Eta Car. In addition, a quite peculiar shape of the spectral energy distribution has been determined. However, no time modulation on orbital time scales (as predicted by Reimer et al. 2006) could be observed so far.