Thermal evolution of neutron stars in soft X-ray transients with thermodynamically consistent models of the accreted crust
arXiv:2303.08716 · doi:10.1093/mnras/stad1309
Abstract
Thermal emission of neutron stars in soft X-ray transients (SXTs) in a quiescent state is believed to be powered by the heat deposited in the stellar crust due to nuclear reactions during accretion (deep crustal heating paradigm). Confronting observations of SXTs with simulations helps to verify theoretical models of the dense matter in the neutron stars. Usually, such simulations were carried out assuming that the free neutrons and nuclei in the inner crust move together. A recently proposed thermodynamically consistent approach allows for independent motion of the free neutrons. We simulate the thermal evolution of the SXTs within the thermodynamically consistent approach and compare the results with the traditional approach and with observations. For the latter, we consider a collection of quasi-equilibrium thermal luminosities of the SXTs in quiescence and the observed neutron star crust cooling in SXT MXB 165929. We test different models of the equation of state and baryon superfluidity and take into account additional heat sources in the shallow layers of neutron-star crust (the shallow heating). We find that the observed quasi-stationary thermal luminosities of the SXTs can be equally well fitted using the traditional and thermodynamically consistent models, provided that the shallow heat diffusion into the core is taken into account. The observed crust cooling in MXB 165929 can also be fitted in the frames of both models, but the choice of the model affects the derived parameters responsible for the thermal conductivity in the crust and for the shallow heating.
11 pages, 13 figures, 2 tables, accepted by MNRAS. In v2, beside minor text improvements, caption and headers of the tables are corrected and a few observational points in figures are updated; in v.3, a few typos in the reference list are fixed
References in corpus (24)
- Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. XII: Stiffness and stability of neutron-star matter
- Neutron Stars and the Nuclear Equation of State
- Models of crustal heating in accreting neutron stars
- Tests of the nuclear equation of state and superfluid and superconducting gaps using the Cassiopeia A neutron star
- Thermal luminosities of cooling neutron stars
- Cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29
- Spread of Matter over a Neutron-Star Surface During Disk Accretion: Deceleration of Rapid Rotation
- Cooling of Accretion-Heated Neutron Stars
- Effective pairing interactions with isospin density dependence
- Cooling of the crust in the neutron star low-mass X-ray binary MXB 1659-29
- New Conductive Opacities for White Dwarf Envelopes
- Equation of state of low--density neutron matter and the pairing gap
- Heat blanketing envelopes of neutron stars
- Thermal states of neutron stars with a consistent model of interior
- Crust structure and thermal evolution of neutron stars in soft X-ray transients
- Thermodynamically consistent equation of state for an accreted neutron star crust
- Electron conduction opacities at the transition between moderate and strong degeneracy: Uncertainties and impact on stellar models
- Experimental constraints on shallow heating in accreting neutron-star crusts
- Deep crustal heating for realistic compositions of thermonuclear ashes
- Constraining the properties of dense neutron star cores: The case of the low-mass X-ray binary HETE J1900.1-2455
- Fast neutrino cooling in the accreting neutron star MXB 1659-29
- Partially accreted crusts of neutron stars
- Broad-band X-ray spectra and timing of the accretion-powered millisecond pulsar Swift J1756.92508 during its 2018 and 2019 outbursts
- Model of heat diffusion in the outer crust of bursting neutron stars
Cited by in corpus (7)
- Gapless neutron superfluidity can explain the late time cooling of transiently accreting neutron stars
- Cooling of neutron stars in soft X-ray transients with realistic crust composition
- Gapless neutron superfluidity in the crust of the accreting neutron stars KS 1731-260 and MXB 1659-29
- Gravitational wave asteroseismology of accreting neutron stars in a steady state
- A solution to the tension of burning on neutron stars and nuclear physics
- Layers of electron captures in the crust of accreting neutron stars
- Crustal lattice pressure as a source of neutron star mountains