Speaker
Description
Neutron stars provide a unique astrophysical laboratory for probing dark matter under extreme density and strong gravity. Motivated by dark-sector interpretations of the neutron lifetime anomaly, we investigate neutron-to-dark-matter conversion in dense neutron-star matter and its impact on the equation of state and stellar observables.
We model baryonic matter within a non-linear $\sigma$--$\omega$--$\rho$ relativistic mean-field framework and include a fermionic dark component with repulsive self-interactions. By exploring the dark-particle mass and coupling parameter space, we study how neutron-to-dark-matter conversion modifies neutron-star masses, radii, and tidal deformabilities.
To reduce the dependence on the uncertain baryonic equation of state, we perform the analysis using a set of baseline nucleonic equations of state rather than a single reference model. Confronting the resulting stellar sequences with massive-pulsar observations, gravitational-wave tidal constraints, and NICER mass--radius measurements allows us to identify dark-sector regions that are robustly excluded or remain compatible with current observations. Our results provide constraints on neutron dark-decay scenarios that are less dependent on the baryonic equation of state, connecting dark matter physics, the neutron lifetime anomaly, and supranuclear-density matter in neutron stars.