Is There a Crisis in Neutron Star Physics?

TL;DR

This paper discusses potential crises in neutron star physics, highlighting that recent observations and theoretical models of 'black widow' binaries suggest neutron star masses exceeding 2 solar masses, challenging current equations of state.

Contribution

It presents evidence that both observations and models indicate neutron star masses above 2 solar masses, questioning the validity of existing microphysical descriptions.

Findings

Observed neutron star masses > 2 M_sun

Theoretical models predict masses > 2 M_sun

Potential crisis in neutron star physics

Abstract

We shall show in this report that the theoretical evolution of a particular class of systems containing a neutron star, the so-called "black widow" binaries, suggest masses above the $\sim 2 M_{\odot}$, a fact that would bring serious concerns about the right description of the equation of state above the saturation density. Moreover, so far the actual determinations of masses for these systems consistently give values above $2 M_{\odot}$, reinforcing the quandary. In this sense, and given that the confirmation of these ideas would create problems for the microphysical description, we argue that a crisis could be "in the works" in neutron star physics.