The fate of the binary neutron star (NS) merger remnants hinges sensitively upon the NS equation of state and the threshold mass, $M_{ \rm ls}$, that separates a long-lived from a short-lived NS remnant. The nature of the electromagnetic counterparts is also influenced by the remnant type, particularly in determining whether a gamma-ray burst from a compact binary merger (cbGRB) is of short or long duration. We propose a novel approach to probe $M_{ \rm ls}$ by linking it to the estimated observed ratio of long to short cbGRBs. We find that current observations broadly favour a relatively high value for this transition, $M_{ \rm ls}\simeq 1.3 M_{ \rm TOV}$, for which $ M_{ \rm TOV} \lesssim 2.6\,M_\odot $, consistent with numerical simulations, as also shown here. Our results disfavour nuclear physics scenarios that would lead to catastrophic pressure loss at a few times nuclear density and temperatures of tens of MeV, leading to a rapid gravitational collapse of binaries with total mass $M \lesssim 1.3 M_{ \rm TOV}$. Future individual gravitational wave events with on-axis cbGRBs can further bound $M_{ \rm ls}$.
Categories: astro-ph.HE