r-mode instability of neutron stars in low-mass X-ray binaries: effects of Fermi surface depletion and superfluidity of dense matter
| Autor: | Jianmin Dong |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physics
High Energy Astrophysical Phenomena (astro-ph.HE) Nuclear Theory 010308 nuclear & particles physics Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Fermi surface Astrophysics Nuclear matter 01 natural sciences Instability Superfluidity Nuclear Theory (nucl-th) Neutron star Space and Planetary Science 0103 physical sciences Neutron Nucleon Astrophysics - High Energy Astrophysical Phenomena 010303 astronomy & astrophysics Urca process |
| Popis: | The nucleon-nucleon correlation between nucleons leads to the Fermi surface depletion measured by a $Z$-factor in momentum distribution of dense nuclear matter. The roles of the Fermi surface depletion effect ($Z$-factor effect) and its quenched neutron triplet superfluidity of nuclear matter in viscosity and hence in the gravitational-wave-driven $r$-mode instability of neutron stars (NSs) are investigated. The bulk viscosity is reduced by both the two effects, especially the superfluid effect at low temperatures which is also able to reduce the inferred core temperature of NSs. Intriguingly, due to the neutron superfluidity, the core temperature of the NSs in known low-mass X-ray binaries (LMXBs) are found to be clearly divided into two groups: high and low temperatures which correspond to NSs with short and long recurrence times for nuclear-powered bursts respectively. Yet, a large number of NSs in these LMXBs are still located in the $r$-mode instability region. If the density-dependent symmetry energy is stiff enough, the occurence of direct Urca process reduces the inferred core temperature by about one order of magnitude. Accordingly, the contradiction between the predictions and observations is alleviated to some extent, but some NSs are still located inside the unstable region. 12 pages, 5 figures |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|