THE GALACTIC super(26)AL EMISSION MAP AS REVEALED BY INTEGRAL SPI

Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The super(26)Al emission is a good illustration: the only available super(26)Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrum...

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Bibliographic Details
Published inThe Astrophysical journal Vol. 801; no. 2; pp. 1 - 15
Main Authors Bouchet, Laurent, Jourdain, Elisabeth, Roques, Jean-Pierre
Format Journal Article
LanguageEnglish
Published 10.03.2015
Subjects
Algorithms
Comptel
Emission
Emission analysis
Enrichment
Flux
Gamma rays
Mathematical models
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Summary:Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The super(26)Al emission is a good illustration: the only available super(26)Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission offers a unique opportunity to enrich this first result. In this paper, 2 x 10 super(8) s of data accumulated between 2003 and 2013 are used to perform a dedicated analysis, aiming to deeply investigate the spatial morphology of the super(26)Al emission. The data are first compared with several sky maps based on observations at various wavelengths to model the super(26)Al distribution throughout the Galaxy. For most of the distribution models, the inner Galaxy flux is compatible with a value of 3.3 x 10 super(-4) photons cm super(-2) s super(-1), while the preferred template maps correspond to young stellar components such as core-collapse supernovae (SNe), Wolf-Rayet stars, and massive AGB stars. To get more details about this emission, an image reconstruction is performed using an algorithm based on the maximum-entropy method. In addition to the inner Galaxy emission, several excesses suggest that some sites of emission are linked to the spiral arm structure. Lastly, an estimation of the super(60)Fe line flux, assuming a spatial distribution similar to super(26)Al line emission, results in a super(60)Fe-to- super(26)Al ratio around 0.14, which agrees with the most recent studies and with the SN explosion model predictions.
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/801/2/142