A study of possible density profiles of hydrogen gas of Milky Way Galaxy consistent with observed cosmic ray spectra [HEAP]


Secondary cosmic rays (CRs) (e.g. boron, antiproton) play an important role to understand the propagation of CRs in the Milky Way Galaxy. Such secondary CRs are produced due to interaction of primary CRs with the gaseous components of interstellar medium (ISM). We, here, consider mainly molecular, atomic, and ionized components of hydrogen gas for our study. Recent observations and hydrodynamical simulations provide new forms of density profiles of hydrogen gas in Milky Way Galaxy. Our goal in this work is to study the effect of plausible density profiles of hydrogen gas, consistent with the observed CR spectra, on the propagation parameters used for Galactic CR propagation. To achieve such a goal, we have taken into account the DRAGON code, which is widely used to study the propagation of CRs, as a tool to study the propagation parameters by fitting the observed primary and secondary CR spectra. In the DRAGON code, we have implemented our chosen density profiles, based on realistic observation in radio, X-ray and gamma-ray wavebands, and hydrodynamical simulations, of interstellar hydrogen gas and studied the propagation parameters needed to fit the observed CR spectra.

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S. Biswas and N. Gupta
Tue, 13 Feb 18

Comments: 16 pages, 7 captioned figures