86 research outputs found
Confronting strange stars with compact-star observations and new physics
Strange stars ought to exist in the universe according to the strange quark
matter hypothesis, which states that matter made of roughly equal numbers of
up, down, and strange quarks could be the true ground state of baryonic matter
rather than ordinary atomic nuclei. Theoretical models of strange quark matter,
such as the standard MIT bag model, the density-dependent quark mass model, or
the quasi-particle model, however, appear to be unable to reproduce some of the
properties (masses, radii and tidal deformabilities) of recently observed
compact stars. This is different if alternative gravity theory (e.g.,
non-Newtonian gravity) or dark matter (e.g., mirror dark matter) are
considered, which resolve these issues. The possible existence of strange stars
could thus provide a clue to new physics, as discussed in this review.Comment: 26 pages, 11 figures. Review paper accepted for publication in
Univers
Radiative viscosity of neutron stars
We study non-linear effects of radiative viscosity of matter in neutron
stars for both direct Urca process and modified Urca process, and find that
non-linear effects will decrease the ratio of radiative viscosity to bulk
viscosity from 1.5 to 0.5 (for direct Urca process) and 0.375 (for modified
Urca process). Which means that for small oscillations of neutron star, the
large fraction of oscillation energy is emitted as neutrinos; but for large
enough ones, bulk viscous dissipation dominates.Comment: 11pages, 4 figure
The role of -mode damping in the thermal evolution of neutron stars
The thermal evolution of neutron stars (NSs) is investigated by coupling with
the evolution of -mode instability that is described by a second
order model.The heating effect due to shear viscous damping of the
-modes enables us to understand the high temperature of two young
pulsars (i.e., PSR B0531+21 and RX J0822-4300) in the framework of the simple
NS model, without superfluidity or exotic particles.Moreover, the light
curves predicted by the model within an acceptable parameter regime may
probably cover all of the young and middle-aged pulsars in the panel, and an artificially strong superfluidity invoked
in some early works is not needed here. Additionally, by considering the
radiative viscous damping of the -modes, a surprising extra cooling
effect is found, which can even exceed the heating effect sometimes although
plays an ignorable role in the thermal history.Comment: 12 pages, 3 figure
- …