Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Birth Function for Black Holes and Neutron Stars in Close Binaries   The mass function for black holes and neutron stars at birth is explored for
mass-losing helium stars. These should resemble, more closely than similar
studies of single hydrogen-rich stars, the results of evolution in close binary
systems. The effects of varying the mass-loss rate and metallicity are
calculated using a simple semi-analytic approach to stellar evolution that is
tuned to reproduce detailed numerical calculations. Though the total fraction
of black holes made in stellar collapse events varies considerably with
metallicity, mass-loss rate, and mass cutoff, from 5$\%$ to 30$\%$, the shapes
of their birth functions are very similar for all reasonable variations in
these quantities. Median neutron star masses are in the range 1.32 - 1.37
$M_\odot$ regardless of metallicity. The median black hole mass for solar
metallicity is typically 8 to 9 $M_\odot$ if only initial helium cores below 40
$M_\odot$ (ZAMS mass less than 80 $M_\odot$) are counted, and 9 - 13 $M_\odot$,
in most cases, if helium cores with initial masses up to 150 $M_\odot$ (ZAMS
mass less than 300 $M_\odot$) contribute. As long as the mass-loss rate as a
function of mass exhibits no strong non-linearities, the black hole birth
function from 15 to 35 $M_\odot$ has a slope that depends mostly on the initial
mass function for main sequence stars. These findings imply the possibility of
constraining the initial mass function and the properties of mass loss in close
binaries using ongoing measurements of gravitational wave radiation. The
expected rotation rates of the black holes are briefly discussed.

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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: nlin