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Title: Cooling of neutron stars in soft x-ray transients

Thermal states of neutron stars in soft x-ray transients (SXRTs) are thought to be determined by “deep crustal heating” in the accreted matter that drives the quiescent luminosity and cooling via emission of photons and neutrinos from the interior. In this work, we assume a global thermal steady state of the transient system and calculate the heating curves (quiescent surface luminosity as a function of mean accretion rate) predicted from theoretical models, taking into account variations in the equations of state, superfluidity gaps, thickness of the light element layer, and a phenomenological description of the direct Urca threshold. We further provide a statistical analysis on the uncertainties in these parameters, and compare the overall results with observations of several SXRTs, in particular the two sources containing the coldest (SAX J1808.4-3658) and the hottest (Aql X-1) neutron stars. Interpretation of the observational data indicates that the direct Urca process is required for the most massive stars and also suggests small superfluid gaps.
Authors:
 [1] ; ORCiD logo [2]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Physics Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; NSF PHY 1554876; 0711134
Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 96; Journal Issue: 3; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Science Foundation (NSF)
Contributing Orgs:
Univ. of Washington, Seattle, WA (United States). Inst. for Nuclear Theory
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; neutron stars and pulsars; composition of astronomical objects; Monte Carlo methods
OSTI Identifier:
1460178
Alternate Identifier(s):
OSTI ID: 1378414

Han, Sophia, and Steiner, Andrew W. Cooling of neutron stars in soft x-ray transients. United States: N. p., Web. doi:10.1103/PhysRevC.96.035802.
Han, Sophia, & Steiner, Andrew W. Cooling of neutron stars in soft x-ray transients. United States. doi:10.1103/PhysRevC.96.035802.
Han, Sophia, and Steiner, Andrew W. 2017. "Cooling of neutron stars in soft x-ray transients". United States. doi:10.1103/PhysRevC.96.035802. https://www.osti.gov/servlets/purl/1460178.
@article{osti_1460178,
title = {Cooling of neutron stars in soft x-ray transients},
author = {Han, Sophia and Steiner, Andrew W.},
abstractNote = {Thermal states of neutron stars in soft x-ray transients (SXRTs) are thought to be determined by “deep crustal heating” in the accreted matter that drives the quiescent luminosity and cooling via emission of photons and neutrinos from the interior. In this work, we assume a global thermal steady state of the transient system and calculate the heating curves (quiescent surface luminosity as a function of mean accretion rate) predicted from theoretical models, taking into account variations in the equations of state, superfluidity gaps, thickness of the light element layer, and a phenomenological description of the direct Urca threshold. We further provide a statistical analysis on the uncertainties in these parameters, and compare the overall results with observations of several SXRTs, in particular the two sources containing the coldest (SAX J1808.4-3658) and the hottest (Aql X-1) neutron stars. Interpretation of the observational data indicates that the direct Urca process is required for the most massive stars and also suggests small superfluid gaps.},
doi = {10.1103/PhysRevC.96.035802},
journal = {Physical Review C},
number = 3,
volume = 96,
place = {United States},
year = {2017},
month = {9}
}