On the Population of Wind-accreting Neutron Stars in the Galaxy

We explore the possibility that neutron stars accreting from the winds of main-sequence stellar companions account for a significant fraction of low-luminosity, hard X-ray sources (LX ≲ 1035 ergs s-1; 1-10 keV) in the Galaxy. This work was motivated by recent Chandra observations of the Galactic center by Wang, Gotthelf, & Lang. Our calculations indicate that many of the discrete X-ray sources detected in this survey may be wind-accreting neutron stars and that many more may be discovered with deeper X-ray observations. We propose that an infrared observing campaign be undertaken to search for the stellar counterparts of these X-ray sources. If future observations reveal that a large fraction of the X-ray sources are wind-accreting neutron stars, this should provide an important calibration point for massive binary population synthesis studies.