Speaker
Description
We investigate the influence of dark matter (DM) on the structure
and stability of hybrid and twin stars within a two-fluid framework
in which DM interacts with baryonic matter purely through gravity.
The baryonic sector is described using relativistic mean-field theory
for nucleonic matter and a constant sound-speed parametrization for
quark matter, while the DM component is modeled as self-interacting
fermions. We find that the presence of DM suppresses the emergence of
hybrid and twin star branches compared with DM-free configurations.
The degree of suppression depends sensitively on the phase-transition
pressure and the energy-density discontinuity for fixed sound speed,
as well as on the DM particle mass and fractional abundance. Stars
featuring DM-dominated cores or halos are governed primarily by DM
properties, whereas the emergence of twin or hybrid configurations re-
mains controlled by the quark-matter equation of state. Incorporating
current observational constraints further narrows the allowed parameter space for twin stars in both scenarios.
