Diffuse gamma-rays from galactic halos

M. Pohl

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arXiv · astro-ph/9603046

Diffuse gamma-rays from galactic halos

M. Pohl

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Abstract

Here we review our current knowledge on diffuse gamma-rays from galactic halos. Estimates of the relative contribution of the various emission processes at low and high latitudes are compared to the data over 6 decades in energy. The observed spectral shape differs from what was expected, especially at ver low and very high energies. In the latter case, above 1 GeV, the sky emission related to gas exceeds the expected pi^0 decay spectrum. At energies below 1 MeV the relatively high gamma-ray intensity indicates at high density of nearly relativistic electrons which would have a strong influence on the energy and ionisation balance of the interstellar medium. Given the EGRET results for the Magellanic Clouds the gamma-ray emissivity in the outer halo is probably small, so that a substantial amount of baryonic dark matter may be hidden at 20-50 kpc radius without inducing observable gamma-ray emission.

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M. Pohl. 1996-03-12. Diffuse gamma-rays from galactic halos. https://arxiv.org/abs/astro-ph/9603046

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