Available formats: HTML | PDF | (gzipped) PostScript
Letter to the Editor
H2 dark matter in the galactic halo from EGRET
P.M.W. Kalberla 1,
Yu.A. Shchekinov 2,3 and
R.-J. Dettmar 4
Received 8 July 1999 / Accepted 2 September 1999
We present a model for the interpretation of the -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 -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 -ray distribution can be explained best by models with a flattened halo distribution of axis ratio . If optical depth effects are important, the clumps must have radii of AU and masses of . This would result in a total mass of for such clumps and contribute with to the local surface density.
Key words: Galaxy: halo gamma rays: observations cosmology: dark matter
© European Southern Observatory (ESO) 1999
Online publication: September 24, 1999