Super Neutron Stars

Super Neutron stars.

We understand that (non-rotating) neutron stars should have a certain maximum mass, above which the degenerative pressure of the neutron is insufficient to resist the pressure of a gravitational collapse of the star (which should then collapse to form a ‘black hole’). Calculations of what that mass should be have varied from what was once thought to be the same as the Chandrasekhar limit of 1.4 solar masses, to more recent calculations of 2.16 solar masses. Observations, however, have (so far) shown neutron stars can be as much as 2.3 and 2.4 solar masses or more.

Whatever the maximum mass of a solid non rotating neutron stay may be, it could be increased if the neutron star had a cavity inside its core. If the neutron star is perfectly spherical and likewise the central cavity, then this could be a stable formation. Furthermore, if the neutron star was yet massive enough to become a black hole, then a cavity in the centre would be a smart way of it avoiding becoming a singularity (and thereby avoiding many conceptual problems). At its most extreme the neutron star could become a shell or bubble made of ‘neutronium’ (or some even denser material) rather than a point of matter.

The question is; how could such a cavity be formed inside a neutron star?