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Title: Nuclear Reactions in the Crusts of Accreting Neutron Stars

Abstract

X-ray observations of transiently accreting neutron stars during quiescence provide information about the structure of neutron star crusts and the properties of dense matter. Interpretation of the observational data requires an understanding of the nuclear reactions that heat and cool the crust during accretion and define its non-equilibrium composition. We identify here in detail the typical nuclear reaction sequences down to a depth in the inner crust where the mass density is rho = 2 times 10^12 g cm-3 using a full nuclear reaction network for a range of initial compositions. The reaction sequences differ substantially from previous work. We find a robust reduction of crust impurity at the transition to the inner crust regardless of initial composition, though shell effects can delay the formation of a pure crust somewhat to densities beyond rho = 2 times 10^12 g cm^-3. This naturally explains the small inner crust impurity inferred from observations of a broad range of systems. The exception are initial compositions with A > 102 nuclei, where the inner crust remains impure with an impurity parameter of Qimp≈20 owing to the N=82 shell closure. In agreement with previous work, we find that nuclear heating is relatively robust and independentmore » of initial composition, while cooling via nuclear Urca cycles in the outer crust depends strongly on initial composition. This work forms a basis for future studies of the sensitivity of crust models to nuclear physics and provides profiles of composition for realistic crust models.« less

Authors:
 [1];  [2];  [3]; ORCiD logo [4];  [5];  [4]; ORCiD logo [6];  [7];  [8]; ORCiD logo [9];  [10];  [11];  [12]; ORCiD logo [13];  [2];  [14]
  1. Michigan State Univ., East Lansing, MI (United States); Univ. of Notre Dame, Notre Dame, IN (United States); Technological and Higher Education Institute of Hong Kong (Hong Kong)
  2. Univ. of Notre Dame, Notre Dame, IN (United States)
  3. Indian Institute of Technology Ropar, Punjab (India)
  4. Michigan State Univ., East Lansing, MI (United States); Univ. of Notre Dame, Notre Dame, IN (United States)
  5. Mississippi State Univ., Mississippi State, MS (United States)
  6. Michigan State Univ., East Lansing, MI (United States); Univ. of Notre Dame, Notre Dame, IN (United States); Indiana Univ., Bloomington, IN (United States)
  7. Instituto de Fisica da Univ. de Sao Paulo, Sao Paulo (Brazil)
  8. Coastal Carolina Univ., Conway, SC (United States)
  9. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  10. Michigan State Univ., East Lansing, MI (United States); Univ. of Notre Dame, Notre Dame, IN (United States); Univ. of Maryland, College Park, MD (United States)
  11. Univ. of Notre Dame, Notre Dame, IN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  12. Ioffe Institute, Saint Petersburg (Russia)
  13. Univ. of Notre Dame, Notre Dame, IN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  14. Extreme Light Infrastructure-Nuclear Physics, Ilfov (Romania)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mississippi State Univ., Mississippi State, MS (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1454393
Alternate Identifier(s):
OSTI ID: 1459442; OSTI ID: 1463562
Report Number(s):
LA-UR-18-22864
Journal ID: ISSN 1538-4357; TRN: US1901006
Grant/Contract Number:  
AC05-00OR22725; SC0013037; AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Volume: 859; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; dense matter; nuclear reactions; nucleosynthesis; abundances; stars: neutron; X-rays: binaries; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; dense matter – nuclear reactions, nucleosynthesis, abundances – stars: neutron – X-rays: binaries; Atomic and Nuclear Physics; Astronomy and Astrophysics

Citation Formats

Lau, Rita, Beard, Mary, Gupta, Sanjib S., Schatz, H., Afanasjev, A. V., Brown, Edward F., Deibel, A. T., Gasques, Leandro R., Hitt, George Wesley, Hix, William Raphael, Keek, Laurens, Moller, Peter, Shternin, Peter S., Steiner, Andrew W., Wiescher, Michael, and Xu, Yi. Nuclear Reactions in the Crusts of Accreting Neutron Stars. United States: N. p., 2018. Web. doi:10.3847/1538-4357/aabfe0.
Lau, Rita, Beard, Mary, Gupta, Sanjib S., Schatz, H., Afanasjev, A. V., Brown, Edward F., Deibel, A. T., Gasques, Leandro R., Hitt, George Wesley, Hix, William Raphael, Keek, Laurens, Moller, Peter, Shternin, Peter S., Steiner, Andrew W., Wiescher, Michael, & Xu, Yi. Nuclear Reactions in the Crusts of Accreting Neutron Stars. United States. https://doi.org/10.3847/1538-4357/aabfe0
Lau, Rita, Beard, Mary, Gupta, Sanjib S., Schatz, H., Afanasjev, A. V., Brown, Edward F., Deibel, A. T., Gasques, Leandro R., Hitt, George Wesley, Hix, William Raphael, Keek, Laurens, Moller, Peter, Shternin, Peter S., Steiner, Andrew W., Wiescher, Michael, and Xu, Yi. Thu . "Nuclear Reactions in the Crusts of Accreting Neutron Stars". United States. https://doi.org/10.3847/1538-4357/aabfe0. https://www.osti.gov/servlets/purl/1454393.
@article{osti_1454393,
title = {Nuclear Reactions in the Crusts of Accreting Neutron Stars},
author = {Lau, Rita and Beard, Mary and Gupta, Sanjib S. and Schatz, H. and Afanasjev, A. V. and Brown, Edward F. and Deibel, A. T. and Gasques, Leandro R. and Hitt, George Wesley and Hix, William Raphael and Keek, Laurens and Moller, Peter and Shternin, Peter S. and Steiner, Andrew W. and Wiescher, Michael and Xu, Yi},
abstractNote = {X-ray observations of transiently accreting neutron stars during quiescence provide information about the structure of neutron star crusts and the properties of dense matter. Interpretation of the observational data requires an understanding of the nuclear reactions that heat and cool the crust during accretion and define its non-equilibrium composition. We identify here in detail the typical nuclear reaction sequences down to a depth in the inner crust where the mass density is rho = 2 times 10^12 g cm-3 using a full nuclear reaction network for a range of initial compositions. The reaction sequences differ substantially from previous work. We find a robust reduction of crust impurity at the transition to the inner crust regardless of initial composition, though shell effects can delay the formation of a pure crust somewhat to densities beyond rho = 2 times 10^12 g cm^-3. This naturally explains the small inner crust impurity inferred from observations of a broad range of systems. The exception are initial compositions with A > 102 nuclei, where the inner crust remains impure with an impurity parameter of Qimp≈20 owing to the N=82 shell closure. In agreement with previous work, we find that nuclear heating is relatively robust and independent of initial composition, while cooling via nuclear Urca cycles in the outer crust depends strongly on initial composition. This work forms a basis for future studies of the sensitivity of crust models to nuclear physics and provides profiles of composition for realistic crust models.},
doi = {10.3847/1538-4357/aabfe0},
url = {https://www.osti.gov/biblio/1454393}, journal = {The Astrophysical Journal (Online)},
issn = {1538-4357},
number = 1,
volume = 859,
place = {United States},
year = {2018},
month = {5}
}

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Free Publicly Available Full Text
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Cited by: 4 works
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Figures / Tables:

Figure 1 Figure 1: Column density as a function of mass density for extreme burst ashes. The change in slope around $$ρ$$ = 6 x 10 11 g cm -3 indicates the change of the dominant pressure source from electrons to neutrons.

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Works referenced in this record:

The Rapid Proton Process Ashes from Stable Nuclear Burning on an Accreting Neutron Star
journal, October 1999


rp-process nucleosynthesis at extreme temperature and density conditions
journal, February 1998


Strong neutrino cooling by cycles of electron capture and β− decay in neutron star crusts
journal, December 2013


Mass Measurements Demonstrate a Strong N = 28 Shell Gap in Argon
journal, January 2015


A Survey of Chemical Separation in Accreting Neutron Stars
journal, May 2016


Nuclear Heating and Melted Layers in the Inner Crust of an Accreting Neutron Star
journal, March 2000


Phase separation in the crust of accreting neutron stars
journal, June 2007


Compressible liquid drop nuclear model and mass formula
journal, July 1977


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


Dependence of X-Ray Burst Models on Nuclear Masses
journal, August 2017


Intruder Configurations in the A = 33 Isobars: Mg 33 and Al 33
journal, October 2008


Late-time Cooling of Neutron Star Transients and the Physics of the Inner Crust
journal, April 2017


Deformations of accreting neutron star crusts and gravitational wave emission: Crustal quadrupole moments
journal, December 2000


Physics of Neutron Star Crusts
journal, December 2008


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


Quiescent thermal emission from neutron stars in low-mass X-ray binaries
journal, April 2015


A Strong Shallow heat Source in the Accreting Neutron star maxi J0556-332
journal, August 2015


Fusion reactions in multicomponent dense matter
journal, September 2006


Discovery of X-ray burst triplets in EXO 0748-676
journal, January 2007


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


Collapse of the N = 28 Shell Closure in S 42 i
journal, July 2007


Forecasting Neutron Star Temperatures: Predictability and Variability
journal, December 2013


Nuclear Properties for Astrophysical and Radioactive-Ion-Beam Applications
journal, July 1997


New developments in the calculation of β-strength functions
journal, July 1990


End Point of the rp Process on Accreting Neutron Stars
journal, April 2001


Deep crustal heating in a multicomponent accreted neutron star crust
journal, May 2012


X-ray binaries
journal, October 2006


Nuclear Configurations in the Spin-Orbit Coupling Model. I. Empirical Evidence
journal, April 1950


Neutron star matter at sub-nuclear densities
journal, June 1973


Superburst Models for Neutron Stars with Hydrogen- and Helium-Rich Atmospheres
journal, June 2012


Comment on “Intruder Configurations in the A = 33 Isobars: Mg 33 and Al 33
journal, March 2010


The limits of the nuclear landscape
journal, June 2012


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


Measurements of Fusion Reactions of Low-Intensity Radioactive Carbon Beams on C 12 and their Implications for the Understanding of X-Ray Bursts
journal, May 2014


Nuclear magic numbers: New features far from stability
journal, October 2008


Hydrodynamic Models of type i X-Ray Bursts: Metallicity Effects
journal, June 2010


Models of Type I X-Ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning
journal, November 2007


Influence of shell-quenching far from stability on the astrophysical r-process
journal, July 1995


Daily multiwavelength Swift monitoring of the neutron star low-mass X-ray binary Cen X-4: evidence for accretion and reprocessing during quiescence
journal, October 2013


Neutron star crust cooling in KS 1731−260: the influence of accretion outburst variability on the crustal temperature evolution
journal, July 2016


Urca Cooling Pairs in the Neutron star Ocean and Their Effect on Superbursts
journal, October 2016


Collectivity in 44S
journal, March 1997


Charting the Temperature of the Hot Neutron Star in a Soft X-Ray Transient
journal, February 2001


On Closed Shells in Nuclei. II
journal, June 1949


Nuclear Ground-State Masses and Deformations
journal, March 1995


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


Evidence for crust cooling in the transiently accreting 11-Hz X-ray pulsar in the globular cluster Terzan 5: Crust cooling of the Terzan 5 X-ray pulsar
journal, October 2011


Heating in the Accreted Neutron Star Ocean: Implications for Superburst Ignition
journal, June 2007


Photodisintegration-triggered Nuclear Energy Release in Superbursts
journal, February 2003


Shell and shape evolution at N = 28 : The Mg 40 ground state
journal, April 2014


1 p 3 / 2 Proton-Hole State in Sn 132 and the Shell Structure Along N = 82
journal, April 2014


Probing the Crust of the Neutron star in exo 0748-676
journal, July 2014


The Spin Distribution of Fast-spinning Neutron Stars in Low-mass X-Ray Binaries: Evidence for Two Subpopulations
journal, November 2017


Thermal conductivity and impurity scattering in the accreting neutron star crust
journal, July 2016


Large collection of astrophysical S factors and their compact representation
journal, May 2012


Discovery of 40Mg and 42Al suggests neutron drip-line slant towards heavier isotopes
journal, October 2007


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


A superburst candidate in EXO 1745−248 as a challenge to thermonuclear ignition models: Superburst in the NS EXO 1745−248
journal, September 2012


Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars
journal, April 2008


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


Neutron star cooling after deep crustal heating in the X-ray transient KS 1731-260
journal, November 2007


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


Carbon production on accreting neutron stars in a new regime of stable nuclear burning
journal, November 2015


A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)
journal, April 2007


Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust
journal, July 2012


Rapid Neutrino Cooling in the Neutron Star MXB 1659-29
journal, April 2018


Explosive hydrogen burning
journal, January 1981


β decay and isomeric properties of neutron-rich Ca and Sc isotopes
journal, July 2010


Compositionally Driven Convection in the Oceans of Accreting Neutron Stars
journal, March 2011


Explosive Hydrogen Burning during Type I X‐Ray Bursts
journal, January 2008

  • Fisker, Jacob Lund; Schatz, Hendrik; Thielemann, Friedrich‐Karl
  • The Astrophysical Journal Supplement Series, Vol. 174, Issue 1
  • https://doi.org/10.1086/521104

Isotopic r-process abundances and nuclear structure far from stability - Implications for the r-process mechanism
journal, January 1993


Thermonuclear Stability of Material Accreting onto a Neutron Star
journal, December 2003


Dependence of X-Ray Burst Models on Nuclear Reaction Rates
journal, October 2016


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


Cooling of the quasi-persistent neutron star X-ray transients KS 1731-260 and MXB 1659-29
journal, October 2006


Neutron star crust cooling in the Terzan 5 X-ray transient Swift J174805.3–244637
journal, June 2015


N = 82 Shell Quenching of the Classical r -Process “Waiting-Point” Nucleus C d 130
journal, October 2003


Long Type I X‐Ray Bursts and Neutron Star Interior Physics
journal, July 2006


Beta decay of Na 3 1 , 3 2 and Mg 31 : Study of the N =20 shell closure
journal, June 1993


Constraints on Bygone Nucleosynthesis of Accreting Neutron Stars
journal, March 2017


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


Potential cooling of an accretion-heated neutron star crust in the low-mass X-ray binary 1RXS J180408.9−342058
journal, January 2017


Large collection of astrophysical S factors and their compact representation
journal, May 2012


Collapse of the N = 28 Shell Closure in S 42 i
journal, July 2007


Astrophysical S factors for fusion reactions involving C, O, Ne, and Mg isotopes
journal, September 2010


Gravitational Radiation and Rotation of Accreting Neutron Stars
journal, July 1998


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


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


Rapid Neutrino Cooling in the Neutron Star MXB 1659-29
journal, April 2018


Measurements of Fusion Reactions of Low-Intensity Radioactive Carbon Beams on C 12 and their Implications for the Understanding of X-Ray Bursts
journal, May 2014


Shell and shape evolution at N = 28 : The Mg 40 ground state
journal, April 2014


β decay and isomeric properties of neutron-rich Ca and Sc isotopes
journal, July 2010


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


Dependence of X-Ray Burst Models on Nuclear Reaction Rates
journal, October 2016


Probing the Crust of the Neutron star in exo 0748-676
journal, July 2014


CONTINUED NEUTRON STAR CRUST COOLING OF THE 11 Hz X-RAY PULSAR IN TERZAN 5: A CHALLENGE TO HEATING AND COOLING MODELS?
journal, September 2013


A Strong Shallow heat Source in the Accreting Neutron star maxi J0556-332
journal, August 2015


Urca Cooling Pairs in the Neutron star Ocean and Their Effect on Superbursts
journal, October 2016


N = 82 Shell Quenching of the Classical r -Process “Waiting-Point” Nucleus C d 130
journal, October 2003


Collectivity in 44S
journal, March 1997


β-Decay schemes of very neutron-rich sodium isotopes and their descendants
journal, September 1984


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


A Strongly Heated Neutron star in the Transient z Source maxi J0556-332
journal, October 2014


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


Phase separation in the crust of accreting neutron stars
journal, June 2007


Thermal conductivity and phase separation of the crust of accreting neutron stars
journal, February 2009


Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars
journal, April 2008


Multi-Instrument X-Ray Observations of Thermonuclear Bursts with Short Recurrence Times
journal, June 2010


Multi-Zone Models of Superbursts from Accreting Neutron Stars
journal, December 2011


Superburst Models for Neutron Stars with Hydrogen- and Helium-Rich Atmospheres
journal, June 2012


Beta decay of Na 3 1 , 3 2 and Mg 31 : Study of the N =20 shell closure
journal, June 1993


Structure of 55Ti from relativistic one-neutron knockout
journal, May 2009


On Closed Shells in Nuclei. II
journal, June 1949


Nuclear Configurations in the Spin-Orbit Coupling Model. I. Empirical Evidence
journal, April 1950


A Survey of Chemical Separation in Accreting Neutron Stars
journal, May 2016


Compositionally Driven Convection in the Oceans of Accreting Neutron Stars
journal, March 2011


A Signature of Chemical Separation in the Cooling Light Curves of Transiently Accreting Neutron Stars
journal, February 2014


Mass Measurements Demonstrate a Strong N = 28 Shell Gap in Argon
journal, January 2015


New developments in the calculation of β-strength functions
journal, July 1990


Forecasting Neutron Star Temperatures: Predictability and Variability
journal, December 2013


Thermal conductivity and impurity scattering in the accreting neutron star crust
journal, July 2016


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


End Point of the rp Process on Accreting Neutron Stars
journal, April 2001


rp-process nucleosynthesis at extreme temperature and density conditions
journal, February 1998


Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust
journal, July 2012


Deep crustal heating in a multicomponent accreted neutron star crust
journal, May 2012


1 p 3 / 2 Proton-Hole State in Sn 132 and the Shell Structure Along N = 82
journal, April 2014


Intruder Configurations in the A = 33 Isobars: Mg 33 and Al 33
journal, October 2008


Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1
journal, January 2016


Models for Type I X‐Ray Bursts with Improved Nuclear Physics
journal, March 2004


Fusion reactions in multicomponent dense matter
journal, September 2006


Comment on “Intruder Configurations in the A = 33 Isobars: Mg 33 and Al 33
journal, March 2010


    Works referencing / citing this record:

    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


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


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


    Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750−27
    journal, September 2019


    Spallation-altered Accreted Compositions for X-Ray Bursts: Impact on Ignition Conditions and Burst Ashes
    journal, December 2019


    Crust of accreting neutron stars within simplified reaction network
    journal, October 2019


    Neutron transfer reactions in accreting neutron stars
    journal, November 2018


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


    Thermal evolution and quiescent emission of transiently accreting neutron stars
    journal, September 2019