Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffuse gamma-ray emission from the Galactic center and implications of
  its past activities   It has been indicated that low-luminosity active galactic nuclei (LLAGNs) are
accelerating high-energy cosmic-ray (CR) protons in their radiatively
inefficient accretion flows (RIAFs). If this is the case, Sagittarius A* (Sgr
A*) should also be generating CR protons, because Sgr A* is a LLAGN. Based on
this scenario, we calculate a production rate of CR protons in Sgr A* and their
diffusion in the central molecular zone (CMZ) around Sgr A*. The CR protons
diffusing in the CMZ create gamma-rays through pp interaction. We show that the
gamma-ray luminosity and spectrum are consistent with observations if Sgr A*
was active in the past.

21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat