Detection of gamma-ray emission from the Eta-Carinae region

Abstract

We present the results of extensive observations by the gamma-ray AGILE satellite of the Galactic region hosting the Carina nebula and the remarkable colliding wind binary Eta Carinae (η Car) during the period 2007 July-2009 January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the position of η Car. If 1AGL J1043-5931 is associated with the Car system, our data provide the long sought first detection above 100 MeV of a colliding wind binary. The average gamma-ray flux above 100 MeV and integrated over the preperiastron period 2007 July-2008 October is Fγ = (37 ± 5) × 10-8 ph cm-2 s-1 corresponding to an average gamma-ray luminosity of Lγ = 3.4 × 1034 erg s-1 for a distance of 2.3 kpc. We also report a two-day gamma-ray flaring episode of 1AGL J1043-5931 on 2008 October 11-13 possibly related to a transient acceleration and radiation episode of the strongly variable shock in the system. © 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A.