1999/09/03 by P. M. W. Kalberla, Yu. A. Shchekinov, Kalberla, P. M. W. +4
Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9909068
4 pages, 3 figures, to be published in A&A letters
arxiv created 1999/09/03 · openalex publication_date 1999/09/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a model for the interpretation of the gamma-ray background emission from the Galactic halo, which we attribute to interaction of high-energy cosmic rays with dense molecular clumps. In a wide range of clump parameters we calculate the expected gamma-photon flux, taking into account for the first time optical depth effects. This allows us to derive new constraints on masses and sizes of possible molecular clumps and their contribution to the galactic surface density. The observed gamma-ray distribution can be explained best by models with a flattened halo distribution of axis ratio ~ 0.3. If optical depth effects are important, the clumps must have radii of ~ 6 AU and masses of ~ 10-3 Msun. This would result in a total mass of ~ 2 1011 Msun for such clumps and contribute with Sigma ~ 140 Msun pc-2 to the local surface density.