Diffuse emission measurement with INTEGRAL/SPI as indirect probe of cosmic-ray electrons and positrons

Understand

Significant advances have been made in the understanding of the diffuse Galactic hard X-ray continuum emission using data from the INTEGRAL observatory.

• The diffuse hard power-law component seen with the INTEGRAL/SPI spectrometer has been identified with inverse-Compton emission from relativistic (GeV) electrons on the cosmic microwave background and Galactic interstellar radiation field.
• In the present analysis, SPI data from 2003 to 2009, with a total exposure time of ~ 10^8 s, are used to derive the Galactic ridge hard X-ray spatial distribution and spectrum between 20 keV and 2.4 MeV.
• Both are consistent with predictions from the GALPROP code.