Soft gamma-ray galactic ridge emission as unveiled by SPI aboard INTEGRAL

Jürgen Knödlseder (1) , Vincent Lonjou (1, 2) , Georg Weidenspointner (1) , Pierre Jean (1) , Andy Strong (3) , Roland Diehl (3) , Bertrand Cordier (4) , Stéphane Schanne (4) , Christoph Winkler (5)

1 CESR - Centre d'étude spatiale des rayonnements
2 CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan
3 MPE - Max-Planck-Institut für Extraterrestrische Physik
4 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
5 ESTEC - European Space Research and Technology Centre

The origin of the soft gamma-ray (200 keV - 1 MeV) galactic ridge emission is one of the long-standing mysteries in the field of high-energy astrophysics. Population studies at lower energies have shown that emission from accreting compact objects gradually recedes in this domain, leaving place to another source of gamma-ray emission that is characterised by a hard power-law spectrum extending from 100 keV up to 100 MeV The nature of this hard component has remained so far elusive, partly due to the lack of sufficiently sensitive imaging telescopes that would be able to unveil the spatial distribution of the emission. The SPI telescope aboard INTEGRAL allows now for the first time the simultaneous imaging of diffuse and point-like emission in the soft gamma-ray regime. We present here all-sky images of the soft gamma-ray continuum emission that clearly reveal the morphology of the different emission components. We discuss the implications of our results on the nature of underlying emission processes and we put our results in perspective of GLAST studies of diffuse galactic continuum emission.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

Jürgen Knödlseder, Vincent Lonjou, Georg Weidenspointner, Pierre Jean, Andy Strong, et al.. Soft gamma-ray galactic ridge emission as unveiled by SPI aboard INTEGRAL. THE FIRST GLAST SYMPOSIUM, Feb 2007, Stanford, United States. pp.130-134, ⟨10.1063/1.2757284⟩. ⟨hal-00166099⟩