We present a hybrid equation of state (EoS) for dense matter that satisfies phenomenological constraints from modern compact star (CS) observations which indicate high maximum masses (M ∼ 2M ⊙ ) and large radii (R > 12 km). The corresponding isospin symmetric EoS is consistent with flow data analyses of heavy-ion collisions and a deconfinement transition at ∼ 0.55 fm −3 . The quark matter phase is described by a 3-flavor Nambu-Jona-Lasinio model that accounts for scalar diquark condensation and vector meson interactions while the nuclear matter phase is obtained within the Dirac-Brueckner-Hartree-Fock (DBHF) approach using the Bonn-A potential. We demonstrate that both pure neutron stars and neutron stars with quark matter cores are consistent with modern CS observations. Hybrid star configurations with a CFL quark core are unstable within the present model. PACS number(s): 04.40. Dg, 12.38.Mh, 26.60.+c, 97.60.Jd
If dark matter is made of mirror baryons, they are present in all
gravitationally bound structures. Here we investigate some effects of mirror
dark matter on neutron stars and discuss possible observational consequences.
The general-relativistic hydrostatic equations are generalized to spherical
objects with multiple fluids that interact by gravity. We use the minimal
parity-symmetric extension of the standard model, which implies that the
microphysics is the same in the two sectors. We find that the mass-radius
relation is significantly modified in the presence of a few percent mirror
baryons. This effect mimics that of other exotica, e.g., quark matter. In
contrast to the common view that the neutron-star equilibrium sequence is
unique, we show that it depends on the relative number of mirror baryons to
ordinary baryons. It is therefore history dependent. The critical mass for core
collapse, i.e., the process by which neutron stars are created, is modified in
the presence of mirror baryons. We calculate the modified Chandrasekhar mass
and fit it with a polynomial. A few percent mirror baryons is sufficient to
lower the critical mass for core collapse by ~0.1 M_sun. This could allow for
the formation of extraordinary compact neutron stars with low mass.Comment: 8 pages, 5 figures. Updated discussion of heating in Section IV and
Conclusions. Added reference
Recent observational results for the masses and radii of some neutron stars
are in contrast with typical observations and theoretical predictions for
"normal" neutron stars. We propose that their unusual properties can be
interpreted as the signature of a dark matter core inside them. This
interpretation requires that the dark matter is made of some form of stable,
long-living or in general non-annihilating particles, that can accumulate in
the star. In the proposed scenario all mass-radius measurements can be
explained with one nuclear matter equation of state and a dark core of varying
relative size. This hypothesis will be challenged by forthcoming observations
and could eventually be a useful tool for the determination of dark matter.Comment: 3 pages, 1 figur
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.