Probing the Cosmic Ray density in the inner Galaxy
Abstract
The galactic diffuse -ray emission, as seen by Fermi Large Area Telescope (LAT), shows a sharp peak in the region around 4 kpc from the Galactic center, which can be interpreted either as due to an enhanced density of cosmic-ray accelerators or to a modification of the particle diffusion in that region. Observations of -rays originating in molecular clouds are a unique tool to infer the cosmic-ray density point by point, in distant regions of the Galaxy. We report here the analysis of 11 yr Fermi-LAT data, obtained in the direction of nine molecular clouds located in the 1.5--4.5 kpc region. The cosmic-ray density measured at the locations of these clouds is compatible with the locally measured one. We demonstrate that the cosmic-ray density gradient inferred from the diffuse gamma-ray emission is the result of the presence of cosmic-ray accelerators rather than a global change of the sea of Galactic cosmic rays due to their propagation.
Cite
@article{arxiv.2101.09510,
title = {Probing the Cosmic Ray density in the inner Galaxy},
author = {Giada Peron and Felix Aharonian and Sabrina Casanova and Ruizhi Yang and Roberta Zanin},
journal= {arXiv preprint arXiv:2101.09510},
year = {2021}
}