Gamma-ray spectroscopy of galactic nucleosynthesis
1 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany
2 Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK
3 Horn & Company Financial Services GmbH, Kaistr. 20, D-40221 Düsseldorf, Germany
4 Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Fischer-Str. 31, D97074 Würzburg, Germany
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Published online: 22 March 2023
Diffuse gamma-ray emission from the decay of radioactive 26Al is a messenger from the nucleosynthesis activity in our current-day galaxy. Because this material is attributed to ejections from massive stars and their supernovae, the gamma-ray signal includes information about nucleosynthesis in massive star interiors as it varies with evolutionary stages, and about their feedback on the surrounding interstellar medium. Our method of population synthesis of massive-star groups has been refined as a diagnostic tool for this purpose. It allows to build a bottom-up prediction of the diffuse gamma-ray sky when known massive star group distributions and theoretical models of stellar evolution and core-collapse supernova explosions are employed. We find general consistency of an origin in such massive-star groups, in particular we also find support for the clumpy distribution of such source regions across the Galaxy, and characteristics of large cavities around these. A discrepancy in the integrated 26Al gamma-ray flux is interpreted as an indication for excess 26Al emission from nearby, distributed in cavities that extend over major regions of the sky.
© The Authors, published by EDP Sciences, 2023
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