skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust

Abstract

An accretion outburst onto a neutron star transient heats the neutron star's crust out of thermal equilibrium with the core. After the outburst, the crust thermally relaxes toward equilibrium with the neutron star core, and the surface thermal emission powers the quiescent X-ray light curve. Crust cooling models predict that thermal equilibrium of the crust will be established $$\approx 1000\,\mathrm{days}$$ into quiescence. Recent observations of the cooling neutron star transient MXB 1659-29, however, suggest that the crust did not reach thermal equilibrium with the core on the predicted timescale and continued to cool after $$\approx 2500\,\mathrm{days}$$ into quiescence. Because the quiescent light curve reveals successively deeper layers of the crust, the observed late-time cooling of MXB 1659-29 depends on the thermal transport in the inner crust. In particular, the observed late-time cooling is consistent with a low thermal conductivity layer near the depth predicted for nuclear pasta that maintains a temperature gradient between the neutron star's inner crust and core for thousands of days into quiescence. As a result, the temperature near the crust–core boundary remains above the critical temperature for neutron superfluidity, and a layer of normal neutrons forms in the inner crust. We find that the late-time cooling of MXB 1659-29 is consistent with heat release from a normal neutron layer near the crust–core boundary with a long thermal time. We also investigate the effect of inner crust physics on the predicted cooling curves of the accreting transient KS 1731-260 and the magnetar SGR 1627-41.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1];  [3]
  1. Michigan State Univ., East Lansing, MI (United States)
  2. Michigan State Univ., East Lansing, MI (United States); McGill Univ., Montreal, QC (Canada)
  3. Univ. of Washington, Seattle, WA (United States); Michigan State Univ., East Lansing, MI (United States)
Publication Date:
Research Org.:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1537184
Grant/Contract Number:  
FG02-00ER41132
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 839; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics

Citation Formats

Deibel, Alex, Cumming, Andrew, Brown, Edward F., and Reddy, Sanjay. Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust. United States: N. p., 2017. Web. doi:10.3847/1538-4357/aa6a19.
Deibel, Alex, Cumming, Andrew, Brown, Edward F., & Reddy, Sanjay. Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust. United States. doi:10.3847/1538-4357/aa6a19.
Deibel, Alex, Cumming, Andrew, Brown, Edward F., and Reddy, Sanjay. Thu . "Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust". United States. doi:10.3847/1538-4357/aa6a19. https://www.osti.gov/servlets/purl/1537184.
@article{osti_1537184,
title = {Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust},
author = {Deibel, Alex and Cumming, Andrew and Brown, Edward F. and Reddy, Sanjay},
abstractNote = {An accretion outburst onto a neutron star transient heats the neutron star's crust out of thermal equilibrium with the core. After the outburst, the crust thermally relaxes toward equilibrium with the neutron star core, and the surface thermal emission powers the quiescent X-ray light curve. Crust cooling models predict that thermal equilibrium of the crust will be established $\approx 1000\,\mathrm{days}$ into quiescence. Recent observations of the cooling neutron star transient MXB 1659-29, however, suggest that the crust did not reach thermal equilibrium with the core on the predicted timescale and continued to cool after $\approx 2500\,\mathrm{days}$ into quiescence. Because the quiescent light curve reveals successively deeper layers of the crust, the observed late-time cooling of MXB 1659-29 depends on the thermal transport in the inner crust. In particular, the observed late-time cooling is consistent with a low thermal conductivity layer near the depth predicted for nuclear pasta that maintains a temperature gradient between the neutron star's inner crust and core for thousands of days into quiescence. As a result, the temperature near the crust–core boundary remains above the critical temperature for neutron superfluidity, and a layer of normal neutrons forms in the inner crust. We find that the late-time cooling of MXB 1659-29 is consistent with heat release from a normal neutron layer near the crust–core boundary with a long thermal time. We also investigate the effect of inner crust physics on the predicted cooling curves of the accreting transient KS 1731-260 and the magnetar SGR 1627-41.},
doi = {10.3847/1538-4357/aa6a19},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 839,
place = {United States},
year = {2017},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 11 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Transport properties of dense matter
journal, May 1976

  • Flowers, E.; Itoh, N.
  • The Astrophysical Journal, Vol. 206
  • DOI: 10.1086/154375

Plastic Damping of AlfvÉN Waves in Magnetar Flares and Delayed Afterglow Emission
journal, December 2015


Structure of cold nuclear matter at subnuclear densities by quantum molecular dynamics
journal, September 2003


Thermal conductivity of neutrons in neutron star cores
journal, July 2001


Nuclear composition and heating in accreting neutron-star crusts
journal, June 2003


A Change in the Quiescent X-Ray Spectrum of the Neutron star Low-Mass X-Ray Binary mxb 1659–29
journal, August 2013


Pulsar Glitches: The Crust is not Enough
journal, December 2012


Nuclear shapes in the inner crust of a neutron star
journal, August 1993


Modules for Experiments in Stellar Astrophysics (Mesa): Binaries, Pulsations, and Explosions
journal, September 2015

  • Paxton, Bill; Marchant, Pablo; Schwab, Josiah
  • The Astrophysical Journal Supplement Series, Vol. 220, Issue 1
  • DOI: 10.1088/0067-0049/220/1/15

Disordered Nuclear Pasta, Magnetic Field Decay, and Crust Cooling in Neutron Stars
journal, January 2015


Models of crustal heating in accreting neutron stars
journal, January 2008


Equation of State of Superfluid Neutron Matter and the Calculation of the S 0 1 Pairing Gap
journal, September 2008


Shape of Nuclei in the Crust of Neutron Star
journal, February 1984

  • Hashimoto, M. -a.; Seki, H.; Yamada, M.
  • Progress of Theoretical Physics, Vol. 71, Issue 2
  • DOI: 10.1143/ptp.71.320

Pairing gaps in nucleonic superfluids
journal, April 1993


Modules for Experiments in Stellar Astrophysics (Mesa): Planets, Oscillations, Rotation, and Massive Stars
journal, August 2013

  • Paxton, Bill; Cantiello, Matteo; Arras, Phil
  • The Astrophysical Journal Supplement Series, Vol. 208, Issue 1
  • DOI: 10.1088/0067-0049/208/1/4

Diagnosing Magnetars with Transient Cooling
journal, November 2002

  • Lyubarsky, Yuri; Eichler, David; Thompson, Christopher
  • The Astrophysical Journal, Vol. 580, Issue 1
  • DOI: 10.1086/345402

Nuclear “pasta” formation
journal, December 2013


Quantum molecular dynamics approach to the nuclear matter below the saturation density
journal, February 1998

  • Maruyama, Toshiki; Niita, Koji; Oyamatsu, Kazuhiro
  • Physical Review C, Vol. 57, Issue 2
  • DOI: 10.1103/physrevc.57.655

Modules for Experiments in Stellar Astrophysics (Mesa)
journal, December 2010

  • Paxton, Bill; Bildsten, Lars; Dotter, Aaron
  • The Astrophysical Journal Supplement Series, Vol. 192, Issue 1
  • DOI: 10.1088/0067-0049/192/1/3

Landau theory of relativistic Fermi liquids
journal, May 1976


Neutron Reactions in Accreting Neutron Stars: A New Pathway to Efficient Crust Heating
journal, December 2008


Neutrino-pair bremsstrahlung in a neutron star crust
journal, October 2014


Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars
journal, September 1998

  • Brown, Edward F.; Bildsten, Lars; Rutledge, Robert E.
  • The Astrophysical Journal, Vol. 504, Issue 2
  • DOI: 10.1086/311578

Cooling of the Crust in the Neutron Star Low-Mass X-Ray Binary MXB 1659-29
journal, October 2008

  • Cackett, Edward M.; Wijnands, Rudy; Miller, Jon M.
  • The Astrophysical Journal, Vol. 687, Issue 2
  • DOI: 10.1086/593703

Shear viscosity and thermal conductivity of nuclear “pasta”
journal, September 2008


Time-variable emission from transiently accreting neutron stars in quiescence due to deep crustal heating
journal, August 2001


Constraints on the Skyrme Equations of State from Properties of Doubly Magic Nuclei
journal, December 2013


Neutrino Emission from the Bubble Phase of Stellar Nuclear Matter
journal, September 1993

  • Leinson, L. B.
  • The Astrophysical Journal, Vol. 415
  • DOI: 10.1086/173199

Renormalization group approach to neutron matter: quasiparticle interactions, superfluid gaps and the equation of state
journal, January 2003


A Chandra Observation of the Neutron Star X‐Ray Transient and Eclipsing Binary MXB 1659−29 in Quiescence
journal, September 2003

  • Wijnands, Rudy; Nowak, Mike; Miller, Jon M.
  • The Astrophysical Journal, Vol. 594, Issue 2
  • DOI: 10.1086/377122

CHANDRA OBSERVATIONS OF SGR 1627–41 NEAR QUIESCENCE
journal, September 2012


Crustal Emission and the Quiescent Spectrum of the Neutron Star in KS 1731−260
journal, November 2002

  • Rutledge, Robert E.; Bildsten, Lars; Brown, Edward F.
  • The Astrophysical Journal, Vol. 580, Issue 1
  • DOI: 10.1086/342745

The Cooling of the Cassiopeia a Neutron star as a Probe of the Nuclear Symmetry Energy and Nuclear Pasta
journal, November 2013


Unraveling the Cooling Trend of the Soft Gamma Repeater SGR 1627-41
journal, September 2003

  • Kouveliotou, C.; Eichler, D.; Woods, P. M.
  • The Astrophysical Journal, Vol. 596, Issue 1
  • DOI: 10.1086/379187

Nuclear Compositions in the Inner Crust of Neutron Stars
journal, October 1979


Mapping Crustal Heating with the Cooling Light Curves of Quasi-Persistent Transients
journal, May 2009


Lower limit on the heat capacity of the neutron star core
journal, February 2017


Structure of Matter below Nuclear Saturation Density
journal, June 1983


A highly resistive layer within the crust of X-ray pulsars limits their spin periods
journal, June 2013

  • Pons, José A.; Viganò, Daniele; Rea, Nanda
  • Nature Physics, Vol. 9, Issue 7
  • DOI: 10.1038/nphys2640

Monitoring Chandra Observations of the Quasi-persistent Neutron Star X-Ray Transient MXB 1659-29 in Quiescence: The Cooling Curve of the Heated Neutron Star Crust
journal, April 2004

  • Wijnands, Rudy; Homan, Jeroen; Miller, Jon M.
  • The Astrophysical Journal, Vol. 606, Issue 1
  • DOI: 10.1086/421081

Untwisting Magnetospheres of Neutron Stars
journal, September 2009


The Long-Term Post-Outburst spin down and flux Relaxation of Magnetar Swift J1822.3–1606
journal, April 2014


Band structure effects for dripped neutrons in neutron star crust
journal, January 2005


Direct Urca process in a neutron star mantle
journal, June 2004


Electrical and thermal conductivities of dense matter in the crystalline lattice phase. II - Impurity scattering
journal, February 1993

  • Itoh, Naoki; Kohyama, Yasuharu
  • The Astrophysical Journal, Vol. 404
  • DOI: 10.1086/172275

The Thermal State of ks 1731−260 After 14.5 Years in Quiescence
journal, December 2016

  • Merritt, Rachael L.; Cackett, Edward M.; Brown, Edward F.
  • The Astrophysical Journal, Vol. 833, Issue 2
  • DOI: 10.3847/1538-4357/833/2/186

Modeling Magnetar Outbursts: flux Enhancements and the Connection with Short Bursts and Glitches
journal, April 2012


Magnetar Outbursts from Avalanches of hall Waves and Crustal Failures
journal, December 2016


Pinning down the superfluid and measuring masses using pulsar glitches
journal, October 2015

  • Ho, Wynn C. G.; Espinoza, Cristóbal M.; Antonopoulou, Danai
  • Science Advances, Vol. 1, Issue 9
  • DOI: 10.1126/sciadv.1500578

Discovery of a New Soft Gamma Repeater, SGR 1627−41
journal, July 1999

  • Woods, Peter M.; Kouveliotou, Chryssa; van Paradijs, Jan
  • The Astrophysical Journal, Vol. 519, Issue 2
  • DOI: 10.1086/312124

Nonuniform neutron-rich matter and coherent neutrino scattering
journal, December 2004


Nonequilibrium shells of neutron stars and their role in sustaining x-ray emission and nucleosynthesis
journal, February 1979


CHANDRA OBSERVATIONS OF SGR 1627–41 NEAR QUIESCENCE
journal, September 2012


Pulsar Glitches: The Crust is not Enough
journal, December 2012


Untwisting Magnetospheres of Neutron Stars
journal, September 2009


Nonequilibrium shells of neutron stars and their role in sustaining x-ray emission and nucleosynthesis
journal, February 1979


Constraints on the Skyrme Equations of State from Properties of Doubly Magic Nuclei
journal, December 2013


Mapping Crustal Heating with the Cooling Light Curves of Quasi-Persistent Transients
journal, May 2009


A Change in the Quiescent X-Ray Spectrum of the Neutron star Low-Mass X-Ray Binary mxb 1659–29
journal, August 2013


Pairing gaps in nucleonic superfluids
journal, April 1993


Lower limit on the heat capacity of the neutron star core
journal, February 2017


Equation of State of Superfluid Neutron Matter and the Calculation of the S 0 1 Pairing Gap
journal, September 2008


Neutron Reactions in Accreting Neutron Stars: A New Pathway to Efficient Crust Heating
journal, December 2008


Shape of Nuclei in the Crust of Neutron Star
journal, February 1984

  • Hashimoto, M. -a.; Seki, H.; Yamada, M.
  • Progress of Theoretical Physics, Vol. 71, Issue 2
  • DOI: 10.1143/PTP.71.320

Shear viscosity and thermal conductivity of nuclear “pasta”
journal, September 2008


Disordered Nuclear Pasta, Magnetic Field Decay, and Crust Cooling in Neutron Stars
journal, January 2015


Nonuniform neutron-rich matter and coherent neutrino scattering
journal, December 2004


Plastic Damping of AlfvÉN Waves in Magnetar Flares and Delayed Afterglow Emission
journal, December 2015


Quantum molecular dynamics approach to the nuclear matter below the saturation density
journal, February 1998

  • Maruyama, Toshiki; Niita, Koji; Oyamatsu, Kazuhiro
  • Physical Review C, Vol. 57, Issue 2
  • DOI: 10.1103/PhysRevC.57.655

The Cooling of the Cassiopeia a Neutron star as a Probe of the Nuclear Symmetry Energy and Nuclear Pasta
journal, November 2013


Nuclear shapes in the inner crust of a neutron star
journal, August 1993


Modeling Magnetar Outbursts: flux Enhancements and the Connection with Short Bursts and Glitches
journal, April 2012


Structure of Matter below Nuclear Saturation Density
journal, June 1983


Nuclear Compositions in the Inner Crust of Neutron Stars
journal, October 1979


Nuclear “pasta” formation
journal, December 2013


The Long-Term Post-Outburst spin down and flux Relaxation of Magnetar Swift J1822.3–1606
journal, April 2014


Renormalization group approach to neutron matter: quasiparticle interactions, superfluid gaps and the equation of state
journal, January 2003


Structure of cold nuclear matter at subnuclear densities by quantum molecular dynamics
journal, September 2003


    Works referencing / citing this record:

    Cooling of Accretion-Heated Neutron Stars
    journal, September 2017

    • Wijnands, Rudy; Degenaar, Nathalie; Page, Dany
    • Journal of Astrophysics and Astronomy, Vol. 38, Issue 3
    • DOI: 10.1007/s12036-017-9466-5

    Continued cooling of the accretion-heated neutron star crust in the X-ray transient IGR J17480–2446 located in the globular cluster Terzan 5
    journal, May 2019

    • Ootes, L. S.; Vats, S.; Page, D.
    • Monthly Notices of the Royal Astronomical Society, Vol. 487, Issue 1
    • DOI: 10.1093/mnras/stz1406

    On the weak magnetic field of millisecond pulsars: does it decay before accretion?
    journal, October 2019

    • Cruces, Marilyn; Reisenegger, Andreas; Tauris, Thomas M.
    • Monthly Notices of the Royal Astronomical Society, Vol. 490, Issue 2
    • DOI: 10.1093/mnras/stz2701

    Nuclear physics of the outer layers of accreting neutron stars
    journal, July 2018

    • Meisel, Zach; Deibel, Alex; Keek, Laurens
    • Journal of Physics G: Nuclear and Particle Physics, Vol. 45, Issue 9
    • DOI: 10.1088/1361-6471/aad171

    Domains and defects in nuclear pasta
    journal, November 2018


    Long-term temperature evolution of neutron stars undergoing episodic accretion outbursts
    journal, September 2019


    Crust-cooling Models Are Insensitive to the Crust–Core Transition Pressure for Realistic Equations of State
    journal, September 2019

    • Lalit, Sudhanva; Meisel, Zach; Brown, Edward F.
    • The Astrophysical Journal, Vol. 882, Issue 2
    • DOI: 10.3847/1538-4357/ab338c

    Nuclear Reactions in the Crusts of Accreting Neutron Stars
    journal, May 2018


    Flux Relaxation after Two Outbursts of the Magnetar SGR 1627–41 and Possible Hard X-Ray Emission
    journal, May 2018

    • An, Hongjun; Cumming, Andrew; Kaspi, Victoria M.
    • The Astrophysical Journal, Vol. 859, Issue 1
    • DOI: 10.3847/1538-4357/aabafb