By the way, the "mass" here is the gravitational mass (i.e., what you'd put into Kepler's laws for a satellite orbiting far away). This is distinct from the baryonic mass, which is what you'd get if you took every particle from a neutron star and weighed it on a distant scale. Because the gravitational redshift of a neutron star is so great, the gravitational mass is about 20% lower than the baryonic mass. Brace yourself for one of my shameless and spectacular displays of ignorance:
Why isn't this a violation of the "equivalence principle," which involves gravitational and inertial mass -- not baryonic mass (a new term to me).
Baryons are subatomic particles that are generally either protons or neutrons. They are the source of stellar--and therefore galactic--luminosity
As for your question, I have not a clue.