Cosmic rays from multiwavelength observations of the Galactic diffuse emission

TL;DR

This paper reviews recent multiwavelength observations of Galactic diffuse emission caused by cosmic rays, discussing model uncertainties and implications for upcoming telescopes like SKA and CTA.

Contribution

It provides a comprehensive overview of recent observational data and compares it with models, highlighting uncertainties and future prospects for cosmic ray studies.

Findings

Diffuse emission observed across multiple wavelengths.

Model uncertainties affect interpretation of cosmic ray properties.

Implications for future telescopes and missions at various energies.

Abstract

Cosmic rays (CRs) generate diffuse emission while interacting with the Galactic magnetic field (B-field), the interstellar gas and the radiation field. This diffuse emission extends from radio, microwaves, through X-rays, to high-energy gamma rays. Diffuse emission has considerably increased the interest of the astrophysical community due to recent detailed observations by Planck, Fermi-LAT, and by very-high-energy Cherenkov telescopes. Observations of this emission and comparison with detailed predictions are used to gain information on the properties of CRs, such as their density, spectra, distribution and propagation in the Galaxy. Unfortunately disentangling and characterizing this diffuse emission strongly depends on uncertainties in the knowledge of unresolved sources, gas, radiation fields, and B-fields, other than CRs throughout the Galaxy. We report here on recent multiwavelength observations of the Galactic diffuse emission, and discuss the diffuse emission produced by CRs and its model uncertainties, comparing observations with predictions. The importance for forthcoming telescopes, especially for the Square Kilometre Array Telescope (SKA) and the Cherenkov Telescope Array (CTA), and for future missions at MeV energies is also addressed.