Abstract
This is the second in a series of three papers constraining the number of detectable old neutron stars in the Galaxy. Here, I present the statistical analysis of a sample of X-ray sources coincident with areas of dark clouds in the Galactic plane. I compare this sample with all sources in the ROSAT All-Sky Survey bright source catalog within 20 of the Galactic plane. I present the re- sults of an identication program of a subset of sources that are compatible with a soft, thermal X-ray spectrum and an eective source temperature of less than 70 eV. The three brightest sources in this sample form an intriguing subgroup. One of them is a previously identied candi- date for an accreting neutron star. I identify the other two sources with hot white dwarf stars. I nd no new ac- creting neutron star candidate in this sample. Based on this result, I derive an upper limit to the space density of accreting neutron stars in elds of Galactic dark clouds of 2s r 1 at a count rate > 0:05 s 1 .
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