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The 2009 Fermi Symposium

A Gamma-ray Source Detected by the Fermi-LAT at the Position of Eta Carinae

Hiromitsu Takahashi


Recently AGILE and Fermi detected a gamma-ray source at the position of Eta Carinae. If the gamma-ray emission is associated with Eta Car, it is the first detection of high energy gamma-rays from colliding wind binaries. This source is continuously bright in gamma rays since the beginning of the LAT survey observation (from 2008 August to 2009 July). The Fermi data do not confirm the presence of the gamma-ray flare in 2008 October that has been reported by AGILE (Tavani et al. 2009). Coinciding with X-ray behavior during 2008 December and 2009 January, the source might increase and decrease the gamma-ray flux, although the amplitude of the flux variation is about one order of magnitude smaller than that observed in the X-ray band. We will present these analysis results and discuss the possible origin of the gamma-ray emission.