Q&A: Supernova Remnants and Neutron Stars
Do neutron stars decay?
The eventual fate of a neutron star depends on its
environment. If left to itself, it is possible that the
neutrons will convert to free quark's and form a strange quark
star, that would be stable until (and if) the quark's decayed
into photon and neutrinos over a time of a million trillion
The other possibility is that the neutron star could accrete
enough material from a companion star or a dense cloud to
push it over the stability limit, whereupon it would collapse
to form a black hole.