Thermal Evolution of Hyperon-Mixed Neutron Stars with Updated Equation of State

Abstract

The presence of hyperons in neutron stars allows the star to cool via the hyperon direct Urca process, which can release energy from the star faster than the standard modified Urca process. Previous cooling calculations verified that hyperons can exist in the core of neutron stars and facilitate direct Urca cooling. In the current article, we first update the observational data on the thermal evolution of neutron stars. Then, adopting the latest realistic equation of state for hyperon-mixed neutron stars, the cooling of these stars is calculated, and the results are compared with the most recently updated observational data. The results confirm that the hyperon scenario can explain the thermal evolution of all observed stars, including the faster cooling of some of these stars if their fast cooling is substantially suppressed due to the presence of hyperon superfluidity in moderately massive stars.