Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Source population synthesis and the Galactic diffuse gamma-ray emission   Population synthesis is used to study the contribution from undetected
sources to the Galactic ridge emission measured by EGRET. Synthesized source
counts are compared with the 3rd EGRET catalogue at low and high latitudes. For
pulsar-like populations, 5-10% of the emission >100 MeV comes from sources
below the EGRET threshold. A steeper luminosity function can increase this to
20% without violating EGRET source statistics. Less luminous populations can
produce much higher values without being detected. Since the unresolved source
spectrum is different from the interstellar spectrum, it could provide an
explanation of the observed MeV and GeV excesses above the predictions, and we
give an explicit example of how this could work.

37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
19
The categories of this paper are: eess