Updated Estimates of Postmerger Gravitational Wave Energy Released in GW170817 and the Maximum Neutron Star Mass

In this work, benefiting from the increased sample of neutron stars with measured masses and radii as well as the incorporation of the chiral effective field theory and perturbative quantum chromodynamics constraints, the tidal parameter κ 2 T is constrained to be 7 8 − 11 + 17 (68.3% credible interval, mainly adopted in this work unless mentioned specifically) for the binary neutron stars involved in GW170817. Such a κ 2 T is in favor of strong gravitational-wave radiation in the postmerger phase, and the corresponding energy is estimated to be E GW , p ≃ 0.05 1 − 0.017 + 0.022 M ⊙ c 2 . Assuming the remnant from binary neutron star merger is a supramassive neutron star, as suggested by the modeling of the electromagnetic counterparts of GW170817, we examine the maximum mass of nonrotating neutron stars ( M TOV ) while accounting for the uncertainty in the remnant’s lifetime ( t c ). Our results show that M TOV varies from 2.0 9 − 0.09 + 0.11 M ⊙ for t c = 0.1 s to 2.1 8 − 0.09 + 0.10 M ⊙ for t c = 1 s. This result is consistent with that independently inferred from the reconstruction of the equation of state of neutron star matter, i.e., M TOV , exc = 2.1 6 − 0.07