Speaker
Description
The hot neutron star cools down due to the loss of neutrinos produced by the scattering of particles mainly inside the core, which enables us to probe the state of high-density matter through temperature observations. Recent X-ray observations have confirmed the existence of too cold
isolated neutron stars beyond the standard cooling scenario without rapid cooling (i.e., minimal cooling scenario), which may imply the existence of exotic particles such as mesons, hyperons, and
quarks. Among them, hyperons are thought to be a powerful candidate for the rapid cooling process known as the hyperon direct Urca process to explain cold neutron stars, in addition to another candidate, the nucleon direct Urca process. However, because of the large uncertainties of baryon superfluidity/superconductivity, whether such direct Urca cooling can work efficiently as a rapid cooling mechanism is controversial. For instance, strong proton superconductivity could suppress both of them. We utilize the latest equation of state with exotic matter hyperons and Kaon condensation (i.e., Y+K phase), and discuss the impact of the Y+K phase on cooling curves, focusing on
the role of Kaon Urca process and proton superconductivity. We also discuss the possibility to "see" the signature of K condensation from temperature observations, i.e., to realize the situation where the Kaon Urca process is dominant.