We investigate the distribution of neutron star masses in different populations of binaries , employing Bayesian statistical techniques .
In particular , we explore the differences in neutron star masses between sources that have experienced distinct evolutionary paths and accretion episodes .
We find that the distribution of neutron star masses in non-recycled eclipsing high-mass binaries as well as of slow pulsars , which are all believed to be near their birth masses , has a mean of 1.28 ~ { } M _ { \odot } and a dispersion of 0.24 ~ { } M _ { \odot } .
These values are consistent with expectations for neutron star formation in core-collapse supernovae .
On the other hand , double neutron stars , which are also believed to be near their birth masses , have a much narrower mass distribution , peaking at 1.33 ~ { } M _ { \odot } but with a dispersion of only 0.05 ~ { } M _ { \odot } .
Such a small dispersion can not easily be understood and perhaps points to a particular and rare formation channel .
The mass distribution of neutron stars that have been recycled has a mean of 1.48 ~ { } M _ { \odot } and a dispersion of 0.2 ~ { } M _ { \odot } , consistent with the expectation that they have experienced extended mass accretion episodes .
The fact that only a very small fraction of recycled neutron stars in the inferred distribution have masses that exceed \sim 2 ~ { } M _ { \odot } suggests that only a few of these neutron stars cross the mass threshold to form low mass black holes .