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The Galaxy in Hard X-Rays/soft Gamma-Rays

The Galaxy in Hard X-Rays/soft Gamma-Rays

Date: 25 March 2008
Satellite: INTEGRAL
Depicts: Galactic emission in four bands between 25 and 600 keV
Copyright: ESA

A recent re-determination of the global Galactic emission in the 20 keV - 8 MeV energy range with the SPI telescope on INTEGRAL shows the transition from a source-dominated to a diffuse-emission dominated sky.

This confirms that individual sources determine the observed emission of the Galaxy between 20 keV and 200 keV, and that the positron-annihilation emission dominates above 300 keV to peak with the bulge-dominated 511 keV line emission.

However, with subtraction of these two components, residual diffuse emission is detected, with a weak surface brightness but a broad spatial extent. This additional, diffuse emission constitutes a significant fraction of the total emission here, and plays the major part from 600 keV up to 2 MeV. Its spatial distribution appears elongated along the plane of the Galaxy. (Bouchet et al., 2008, accepted for publication in ApJ; astro-ph:0801.2086).

Upgraded theoretical models are now able to explain the observed continuum in terms of interstellar processes, thus solving a long-standing mystery of the origin of this emission.

Last Update: 1 September 2019
4-Dec-2023 10:40 UT

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