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arXiv · 1502.03905

A Population of Ultraluminous X-ray Sources with An Accreting Neutron Star

Yong Shao·Xiang-Dong Li
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Abstract

Most ultraluminous X-ray sources (ULXs) are believed to be X-ray binary systems, but previous observational and theoretical studies tend to prefer a black hole rather than a neutron star accretor. The recent discovery of 1.37 s pulsations from the ULX M82 X-2 has established its nature as a magnetized neutron star. In this work we model the formation history of neutron star ULXs in an M82- or Milky Way-like galaxy, by use of both binary population synthesis and detailed binary evolution calculations. We find that the birthrate is around $10^{-4}\, \rm yr^{-1}$ for the incipient X-ray binaries in both cases. We demonstrate the distribution of the ULX population in the donor mass - orbital period plane. Our results suggest that, compared with black hole X-ray binaries, neutron star X-ray binaries may significantly contribute to the ULX population, and high-mass and intermediate-mass X-ray binaries dominate the neutron star ULX population in M82- and Milky Way-like galaxies, respectively.

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Yong Shao, Xiang-Dong Li. 2015-02-13. A Population of Ultraluminous X-ray Sources with An Accreting Neutron Star. https://doi.org/10.1088/0004-637x%2F802%2F2%2F131

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