2026A&A...706A.132W

We explore the symmetry energy effect on the bulk properties of static neutron stars and rotating millisecond pulsars (MSPs). The unified equations of state (EOSs) are constructed self-consistently within the relativistic mean-field framework from the inner crust to the outer core. To investigate the impact of a unified EOS, which uses the same nuclear interaction for both the crust and core, we compared the results of MSPs with those obtained using non-unified EOSs. These non-unified EOSs match the crust and core EOSs, which have different slopes of symmetry energy. For a given rotational period, we examined how symmetry energy influences the maximum mass, equatorial radius, and deformation from sphericity in MSPs. Our findings indicate that a softer EOS is favored by a higher Keplerian frequency, which corresponds to a smaller L for unified EOSs, but a larger L for the crust in matching EOSs. However, under the slow rotation approximation, there is no significant effect from the symmetry energy slope on the bulk properties of 2 M_⊙ MSPs. In contrast, clear differences are observed for those around and below 1.4 M_⊙.