Dark Matter Heating in Evolving Proto-Neutron Stars: A Two-Fluid Approach

TL;DR

This paper models how non-annihilating dark matter influences the thermal and structural evolution of proto-neutron stars, revealing observable signatures that could serve as probes for dark matter presence.

Contribution

It introduces a two-fluid framework for asymmetric dark matter in proto-neutron stars, highlighting its effects on temperature, composition, and stellar compactness during early evolution.

Findings

Dark matter cores deepen gravitational potential and heat baryonic matter.

Extended dark matter halos support the star externally, leading to cooling.

Dark matter alters hyperon onset and star compactness during deleptonization.

Abstract

Neutron stars (NSs) provide a unique laboratory to probe dark matter (DM) through its gravitational imprint on stellar evolution. We use a two-fluid framework with non-annihilating, asymmetric DM, both fermionic and bosonic, that interacts with ordinary matter (OM) solely through gravity. Within this framework, we track protoneutron stars (PNSs) across their thermal and compositional evolution via quasi-static modeling over the Kelvin--Helmholtz cooling timescale. We uncover a distinct thermal signature: DM cores deepen the gravitational potential, compressing and heating the baryonic matter, while extended DM halos provide external support, leading to cooling of the stellar matter. In contrast, hyperons and other exotic baryons soften the equation of state similarly to DM cores but reduce, rather than increase, the temperature. DM thus alters both temperature and particle distribution profiles in ways that provide a clear diagnostic of its presence. DM cores also enhance compactness and shift hyperon onset, with the strongest effects during deleptonization and neutrino-transparent phases due to reduced neutrino pressure contributions. Consequently, this early thermal evolution, observable through supernova neutrino light curves and young pulsar cooling curves, offers a direct, testable probe of DM in NSs.