Cosmic Rays and Interstellar Medium with Gamma-Ray Observations at MeV Energies

TL;DR

Advancing gamma-ray observations at MeV energies can significantly improve our understanding of low-energy cosmic rays, their sources, and their impact on the interstellar medium and galaxy evolution.

Contribution

This paper highlights the scientific potential of a new gamma-ray telescope with enhanced sensitivity to study low-energy cosmic rays and their interactions in the Galaxy.

Findings

Potential to study low-energy CR spectra and sources.

Insights into CR influence on ISM dynamics and star formation.

Improved gamma-ray detection sensitivity over previous instruments.

Abstract

Latest precise cosmic-ray (CR) measurements and present gamma-ray observations have started challenging our understanding of CR transport and interaction in the Galaxy. Moreover, because the density of CRs is similar to the density of the magnetic field, gas, and starlight in the interstellar medium (ISM), CRs are expected to affect the ISM dynamics, including the physical and chemical processes that determine transport and star formation. In this context, observations of gamma-ray emission at MeV energies produced by the low-energy CRs are very important and urgent. A telescope covering the energy range between ~0.1 MeV and a few GeV with a sensitivity more than an order of magnitude better than previous instruments would allow for the first time to study in detail the low-energy CRs, providing information on their sources, their spectra throughout the Galaxy, their abundances, transport properties, and their role on the evolution of the Galaxy and star formation. Here we discuss the scientific prospects for studies of CRs, ISM (gas, interstellar photons, and magnetic fields) and associated gamma-ray emissions with such an instrument.