June 3, 2026: Adamu Issifu
Affiliation: CFisUC, Department of Physics, University of Coimbra, Portugal
Title: Heating or Cooling? Distinct Thermal Signatures of Dark Matter in Protoneutron Stars
Abstract: Dense compact stars provide unique laboratories for probing dark matter (DM) under conditions inaccessible to terrestrial experiments. Motivated by the absence of conclusive signals in direct-detection searches, we investigate the impact of DM on the structure and thermal evolution of protoneutron stars (PNSs). Using a two-fluid framework in which DM and baryonic matter interact solely through gravity, we study PNSs admixed with asymmetric fermionic and bosonic DM. We show that DM leaves a distinctive thermal imprint whose sign depends on its spatial distribution. A compact DM core deepens the gravitational potential, enhances baryonic compression, and heats the stellar interior, whereas an extended DM halo provides additional gravitational support and reduces the core temperature. This behavior sharply contrasts with that of hyperons, which soften the equation of state and systematically cool the star. We further demonstrate that the nature of the DM–baryon interaction plays a crucial role. While purely gravitationally coupled DM produces heating through compression, nongravitational interactions modeled through a Higgs portal allow DM to act as a thermal reservoir, leading to cooling. These contrasting thermal signatures provide a potential means of distinguishing DM effects from those of exotic baryonic degrees of freedom and may be probed through future multimessenger observations, including supernova neutrino signals and the thermal evolution of young neutron stars. More