Cooling of young neutron stars and dark gauge bosons

TL;DR

This paper investigates how dark gauge bosons could influence the cooling of young neutron stars, deriving constraints on their properties based on observational data and exploring potential hints of their existence in rapid cooling phenomena.

Contribution

It provides new bounds on dark gauge boson parameters from neutron star cooling data and discusses their possible role in explaining rapid cooling of Cas A.

Findings

Bound on dark photon mixing parameter: εm' < 1.5×10^{-8} MeV

Bound on U(1)_{B-L} gauge boson coupling: e' < 10^{-13}

Potential link between rapid Cas A cooling and U(1)_{B-L} gauge boson

Abstract

The standard cooling scenario in the presence of nucleon superfluidity fits rather well to the observation of the neutron stars. It implies that the stellar cooling arguments could place a stringent constraint on the properties of novel particles. We study in particular the cooling rate induced by dark gauge bosons for very young neutron stars: remnants of Cassiopeia A and SN1987A. The cooling is dominantly contributed either by the nucleon pair breaking and formation in the core or by the electron bremsstrahlung in the crust, depending on the age of the stars and the form of the couplings. We compute how much the cooling curve of the young neutron stars could be modified by the extra dark gauge boson emission and obtain the bound for the dark gauge boson when its mass is lower than $\mathcal{O}(0.1)\,{\rm MeV}$; for the dark photon we find the mixing parameter times its mass $\varepsilon m_{\gamma^\prime} < 1.5 \times 10^{-8}\,{\rm MeV}$ and for the ${\rm U}(1)_{B-L}$ gauge boson its coupling to nucleons and electrons $e^\prime < 10^{-13}$. We also discuss the possibility that the rapid cooling of Cas A might provide a hint for the existence of the ${\rm U}(1)_{B-L}$ gauge boson.