Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational-Wave Background from Binary Mergers and Metallicity
  Evolution of Galaxies   The cosmological evolution of the binary black hole (BH) merger rate and the
energy density of the gravitational-wave (GW) background are investigated. To
evaluate the redshift dependence of the BH formation rate, BHs are assumed to
originate from low-metallicity stars, and the relations between the star
formation rate, metallicity and stellar mass of galaxies are combined with the
stellar mass function at each redshift. As a result, it is found that when the
energy density of the GW background is scaled with the merger rate at the local
Universe, the scaling factor does not depend on the critical metallicity for
the formation of BHs. Also taking into account the merger of binary neutron
stars, a simple formula to express the energy spectrum of the GW background is
constructed for the inspiral phase. The relation between the local merger rate
and the energy density of the GW background will be examined by future GW
observations.

33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an