Constraints on axion-like particles and nucleon pairing in dense matter from the hot neutron star in HESS J1731-347

摘要

If the thermal evolution of the hot young neutron star in the supernova remnant HESS J1731-347 is driven by neutrino emission, it provides a stringent constraint on the coupling of light (mass 10 keV) axion-like particles to neutrons. Using Markov-Chain Monte Carlo we find that for the values of axion-neutron coupling g(ann)(2) 7.7 x 10(-20) (90% c.l.) the axion cooling from the bremsstrahlung reaction n + n - n + n + a is too rapid to account for the high observed surface temperature. This implies that the Pecci-Quinn scale or axion decay constant f(a) 6.7 x 10(7) GeV for KSVZ axions and f(a) 1.7 x 10(9) GeV for DFSZ axions. The high temperature of this neutron star also allows us to tighten constraints on the size of the nucleon pairing gaps.