Gravitational synchronization in bosonic dark matter admixed neutron stars
Phys. Rev. D 114, 084046 – Published 16 October, 2026
DOI: https://doi.org/10.1103/r21b-yysm
Abstract
While the search for dark matter remains a central focus of modern astrophysics and high-energy physics, neutron stars could provide natural laboratories in which the interaction between dark matter and baryonic matter can be studied. In this work, we model dark matter as an ultralight bosonic field, which can accrete onto the neutron star and form a composite object bound through gravity. Using long-term, numerical relativity simulations in spherical symmetry, we extract and analyze the frequency spectra of the radial oscillation modes of fermion-boson stars. Our simulations reveal that the fermionic and bosonic components synchronize through gravitational coupling regardless of the equation of state, enriching their oscillation spectrum. This synchronization leads to new multistate scalar configurations and reshapes the hierarchy of the neutron-star radial modes. We further propose a procedure to compute the values of the new dominant modes as a function of the bosonic mass and discuss how the synchronization mechanism extends beyond spherical symmetry together with its implications for neutron-star physics and gravitational-wave astronomy.
