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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.
The discovery of GW signal from merging neutron stars by LIGO on 17th August 2017 was followed by a short GRB170817A discovered by FERMI and INTEGRAL 1.7 seconds after the loss of the GW signal when it just reached its maximum. Here we present a repr
It is now clear that a subset of supernovae display evidence for jets and are observed as gamma-ray bursts. The angular momentum distribution of massive stellar endpoints provides a rare means of constraining the nature of the central engine in core-
Black holes in binary star systems are vital for understanding the process of pr oducing gravitational wave sources, understanding how supernovae work, and for p roviding fossil evidence for the high mass stars from earlier in the Universe. At the pr
Aims. Large radial velocity variations in the LAMOST spectra of giant stars have been used to infer the presence of unseen companions. Some of them have been proposed as possible black hole candidates. We test this selection by investigating the clas
We investigate observable signatures of a first-order quantum chromodynamics (QCD) phase transition in the context of core collapse supernovae. To this end, we conduct axially symmetric numerical relativity simulations with multi-energy neutrino tran