MAXIMUM MASS INSTABILITY OF NEUTRON-STARS AND WEAK INTERACTION PROCESSES IN DENSE MATTER

We study the stability of equilibrium configurations of neutron stars in the vicinity of maximum allowable mass (mass M congruent-to M(max), central density rho(c) congruent-to rho(c,max)). The effect of weak interaction processes on the dynamical properties of perturbed stars is studied. Linear analysis performed for a specific model of dense matter shows, that due to the slowness of weak interaction processes, the region of configurations stable with respect to infinitesimal radial perturbations extends beyond rho(c,max). Finite amplitude analysis of stability is performed using fully relativistic spherically symmetric hydrodynamical code. We show that for rho(c) close to rho(c,max), configurations with rho(c) < rho(c,max) can become unstable with respect to a finite amplitude perturbation. Similarly, those configurations with rho(c) > rho(c,max), which were stable in the linear regime, can be destabilized, due to non-linear effects, by a small but finite amplitude perturbation which exceeds some threshold value. In all cases, destabilized metastable configurations collapse into a black hole.