Тёмные ядра и гало: как тёмная материя меняет нейтронные звёзды

Dark matter admixed neutron stars are studied via a two-fluid formalism using agnostic hadronic and dark matter equations of state. Dark matter is modeled as a Fermi gas defined only by its low-density equation of state and mass. Hadronic matter is anchored at low densities by chiral effective field theory and at high densities by perturbative QCD; a sound-speed parametrization covers intermediate densities for hadrons and high densities for dark matter, ensuring thermodynamic consistency without bias. Light dark matter forms extended halos that increase tidal deformability, while heavy dark matter forms compact cores that decrease it. Observational constraints thus shift from gravitational-wave tidal deformability for light dark matter to NICER mass–radius data for heavy dark matter. At 1σ, the dark matter fraction is bounded to f_DM ≲ 0.11 for light dark matter. This agnostic framework yields conservative, broadly applicable bounds, and neutron stars with similar masses but very different tidal deformabilities could be a smoking-gun signature of dark matter.