2019ApJ...886...52Z

Using the very recently reported mass 2.14_–0.09^+0.10M_☉ of PSR J0740+6620 together with the data of finite nuclei and the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions, we show that the symmetry energy E_sym(n) cannot be supersoft so that it becomes negative at suprasaturation densities in neutron stars (NSs) and thus may make the NS have a pure neutron matter core. This is in contrast to the fact that using the mass 2.01 ± 0.04M_☉ of PSR J0348+0432 as the NS maximum mass cannot rule out the supersoft high-density E_sym(n). Furthermore, we find the stiffer high-density E_sym(n) based on the existence of 2.14M_☉ NSs leads to a strong constraint of Λ_1.4≥ 348_–51⁺⁸⁸ for the dimensionless tidal deformability of the canonical 1.4M_☉ NS.