Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmic Rays and Interstellar Medium with Gamma-Ray Observations at MeV
  Energies   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.

23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
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The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math