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VI INTEGRAL Workshop, Moscou : Russie, Fédération De (2006)
Imaging the Gamma-Ray Sky with SPI aboard INTEGRAL
Jürgen Knödlseder1, Georg Weidenspointner1, Pierre Jean1, Roland Diehl2, Andrew W. Strong2, H. Halloin3, Bertrand Cordier4, Stéphane Schanne4, Chris Winkler5

The spectrometer SPI on INTEGRAL allows for the first time simultaneous imaging of diffuse and point-like emission in the hard X-ray and soft gamma-ray regime. To fully exploit the capabilities of the instrument, we implemented the MREM image deconvolution algorithm, initially developed for COMPTEL data analysis, to SPI data analysis. We present the performances of the algorithm by means of simulations and apply it to data accumulated during the first 2 mission years of INTEGRAL. Skymaps are presented for the 1809 keV gamma-ray line, attributed to the radioactive decay of 26Al, and for continuum energy bands, covering the range 20 keV - 3 MeV. The 1809 keV map indicates that emission is clearly detected by SPI from the inner Galactic radian and from the Cygnus region. The continuum maps reveal the transition between a point-source dominated hard X-ray sky to a diffuse emission dominated soft gamma-ray sky. From the skymaps, we extract a Galactic ridge emission spectrum that matches well SPI results obtained by model fitting. By comparing our spectrum with the cumulative flux measured by IBIS from point sources, we find indications for the existence of an unresolved or diffuse emission component above ~100 keV.
1 :  CESR - Centre d'étude spatiale des rayonnements
2 :  MPE - MPE
3 :  APC - UMR 7164 - AstroParticule et Cosmologie
4 :  SAp - Service d'Astrophysique
APC - Cosmologie et gravitation
Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique
Image deconvolution – 1809 keV line emission – Galactic continnum emission
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knodlseder-imaging.ps(3.3 MB)
knodlseder-imaging.pdf(1.3 MB)