Rapid Neutrino Cooling in the Neutron Star MXB 1659-29

Edward F. Brown; Andrew Cumming; Farrukh J. Fattoyev; C. J. Horowitz; Dany Page; Sanjay Reddy

doi:10.1103/PhysRevLett.120.182701

Rapid Neutrino Cooling in the Neutron Star MXB 1659-29

Edward F. Brown
, Andrew Cumming
, Farrukh J. Fattoyev
, C. J. Horowitz
, Dany Page
, Sanjay Reddy

Research output: Contribution to journal › Article › peer-review

69 Scopus citations

Abstract

We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e-+νe and inverse) and is consistent with the direct Urca (n→p+e-+νe and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

Original language	English
Article number	182701
Journal	Physical Review Letters
Volume	120
Issue number	18
DOIs	https://doi.org/10.1103/PhysRevLett.120.182701
State	Published - 4 May 2018
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2018 American Physical Society.

Funding

We thank C. Heinke and W. Newton for useful discussion. This work benefited from discussions at the Physics and Astrophysics of Neutron Star Crusts workshop 2016 supported by the National Science Foundation under Grant No.PHY-1430152 (JINA Center for the Evolution of the Elements). A.C. is supported by an NSERC Discovery Grant and is a member of the Centre de Recherche en Astrophysique du Quebec (CRAQ). E.F.B. is supported by the U.S. National Science Foundation Grant No.AST-1516969. F.J.F. and C.J.H. are supported in part by DOE Grants No.DE-FG02-87ER40365 and No.DE-SC0008808. D.P.'s work is partially supported by Conacyt through the Fondo Sectorial de Investigacien para la Educacien, Grant CB-2014-1, No.240512. S.R. acknowledges support from the U.S. Department of Energy Grant No.DE-FG02-00ER41132. We thank the Aspen Center for Physics, which is supported by National Science Foundation Grant No.PHY-1607611, for a stimulating venue for completing this work. We thank C. Heinke and W. Newton for useful discussion. This work benefited from discussions at the Physics and Astrophysics of Neutron Star Crusts workshop 2016 supported by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements). A. C. is supported by an NSERC Discovery Grant and is a member of the Centre de Recherche en Astrophysique du Québec (CRAQ). E. F. B. is supported by the U.S. National Science Foundation Grant No. AST-1516969. F. J. F. and C. J. H. are supported in part by DOE Grants No. DE-FG02-87ER40365 and No. DE-SC0008808. D. P.’s work is partially supported by Conacyt through the Fondo Sectorial de Investigación para la Educación, Grant CB-2014-1, No. 240512. S. R. acknowledges support from the U.S. Department of Energy Grant No. DE-FG02-00ER41132. We thank the Aspen Center for Physics, which is supported by National Science Foundation Grant No. PHY-1607611, for a stimulating venue for completing this work.

Funders	Funder number
Centre de Recherche en Astrophysique du Québec	AST-1516969
Fondo Sectorial de Investigación para la Educación	240512, CB-2014-1
National Science Foundation	1630782, PHY-1430152, 1430152, 1516969
U.S. Department of Energy	DE-SC0008808, DE-FG02-00ER41132, PHY-1607611, DE-FG02-87ER40365
Aspen Center for Physics
Natural Sciences and Engineering Research Council of Canada
Consejo Nacional de Ciencia y Tecnología
National Science Foundation

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10.1103/PhysRevLett.120.182701

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title = "Rapid Neutrino Cooling in the Neutron Star MXB 1659-29",

abstract = "We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e-+νe and inverse) and is consistent with the direct Urca (n→p+e-+νe and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.",

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AU - Reddy, Sanjay

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N2 - We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e-+νe and inverse) and is consistent with the direct Urca (n→p+e-+νe and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

AB - We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e-+νe and inverse) and is consistent with the direct Urca (n→p+e-+νe and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

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Rapid Neutrino Cooling in the Neutron Star MXB 1659-29

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