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A NICER view of PSR J0030+0451: Implications for the dense matter equation of state

A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
Both the mass and radius of the millisecond pulsar PSR J0030+0451 have been inferred via pulse-profile modeling of X-ray data obtained by NASA's Neutron Star Interior Composition Explorer (NICER) mission. In this Letter we study the implications of the mass–radius inference reported for this source by Riley et al. for the dense matter equation of state (EoS), in the context of prior information from nuclear physics at low densities. Using a Bayesian framework we infer central densities and EoS properties for two choices of high-density extensions: a piecewise-polytropic model and a model based on assumptions of the speed of sound in dense matter. Around nuclear saturation density these extensions are matched to an EoS uncertainty band obtained from calculations based on chiral effective field theory interactions, which provide a realistic description of atomic nuclei as well as empirical nuclear matter properties within uncertainties. We further constrain EoS expectations with input from the current highest measured pulsar mass; together, these constraints offer a narrow Bayesian prior informed by theory as well as laboratory and astrophysical measurements. The NICER mass–radius likelihood function derived by Riley et al. using pulse-profile modeling is consistent with the highest-density region of this prior. The present relatively large uncertainties on mass and radius for PSR J0030+0451 offer, however, only a weak posterior information gain over the prior. We explore the sensitivity to the inferred geometry of the heated regions that give rise to the pulsed emission, and find a small increase in posterior gain for an alternative (but less preferred) model. Lastly, we investigate the hypothetical scenario of increasing the NICER exposure time for PSR J0030+0451.
2041-8205
Raaijmakers, Geert
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Riley, Thomas E.
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Watts, Anna L.
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Greif, S. K.
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Morsink, Sharon
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Hebeler, Kai
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Schwenk, Achim
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Hinderer, Tanja
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Nissanke, Samaya
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Guillot, Sebastien
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Arzoumanian, Zaven
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Bogdanov, Slavko
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Chakrabarty, Deepto
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Gendreau, Keith C.
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Ho, Wynn C.G.
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Lattimer, James M.
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Ludlam, Renee M.
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Wolff, Michael T.
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Raaijmakers, Geert
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Riley, Thomas E.
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Watts, Anna L.
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Greif, S. K.
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Morsink, Sharon
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Hebeler, Kai
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Schwenk, Achim
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Hinderer, Tanja
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Nissanke, Samaya
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Guillot, Sebastien
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Arzoumanian, Zaven
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Bogdanov, Slavko
39f20582-4d71-4b1a-ae2a-b266367341ef
Chakrabarty, Deepto
322198a5-4c3a-4369-99ee-b66befa6a518
Gendreau, Keith C.
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Ho, Wynn C.G.
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Lattimer, James M.
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Ludlam, Renee M.
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Wolff, Michael T.
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Raaijmakers, Geert, Riley, Thomas E., Watts, Anna L., Greif, S. K., Morsink, Sharon, Hebeler, Kai, Schwenk, Achim, Hinderer, Tanja, Nissanke, Samaya, Guillot, Sebastien, Arzoumanian, Zaven, Bogdanov, Slavko, Chakrabarty, Deepto, Gendreau, Keith C., Ho, Wynn C.G., Lattimer, James M., Ludlam, Renee M. and Wolff, Michael T. (2019) A NICER view of PSR J0030+0451: Implications for the dense matter equation of state. Astrophysical Journal Letters, 887 (1), [L22]. (doi:10.3847/2041-8213/ab451a).

Record type: Article

Abstract

Both the mass and radius of the millisecond pulsar PSR J0030+0451 have been inferred via pulse-profile modeling of X-ray data obtained by NASA's Neutron Star Interior Composition Explorer (NICER) mission. In this Letter we study the implications of the mass–radius inference reported for this source by Riley et al. for the dense matter equation of state (EoS), in the context of prior information from nuclear physics at low densities. Using a Bayesian framework we infer central densities and EoS properties for two choices of high-density extensions: a piecewise-polytropic model and a model based on assumptions of the speed of sound in dense matter. Around nuclear saturation density these extensions are matched to an EoS uncertainty band obtained from calculations based on chiral effective field theory interactions, which provide a realistic description of atomic nuclei as well as empirical nuclear matter properties within uncertainties. We further constrain EoS expectations with input from the current highest measured pulsar mass; together, these constraints offer a narrow Bayesian prior informed by theory as well as laboratory and astrophysical measurements. The NICER mass–radius likelihood function derived by Riley et al. using pulse-profile modeling is consistent with the highest-density region of this prior. The present relatively large uncertainties on mass and radius for PSR J0030+0451 offer, however, only a weak posterior information gain over the prior. We explore the sensitivity to the inferred geometry of the heated regions that give rise to the pulsed emission, and find a small increase in posterior gain for an alternative (but less preferred) model. Lastly, we investigate the hypothetical scenario of increasing the NICER exposure time for PSR J0030+0451.

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1912.05703 - Accepted Manuscript
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Accepted/In Press date: 16 September 2019
Published date: 12 December 2019

Identifiers

Local EPrints ID: 436749
URI: http://eprints.soton.ac.uk/id/eprint/436749
ISSN: 2041-8205
PURE UUID: 69659222-dd00-4347-9098-f4d3fa97f492
ORCID for Wynn C.G. Ho: ORCID iD orcid.org/0000-0002-6089-6836

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Date deposited: 03 Jan 2020 17:30
Last modified: 27 Jan 2020 13:43

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Contributors

Author: Geert Raaijmakers
Author: Thomas E. Riley
Author: Anna L. Watts
Author: S. K. Greif
Author: Sharon Morsink
Author: Kai Hebeler
Author: Achim Schwenk
Author: Tanja Hinderer
Author: Samaya Nissanke
Author: Sebastien Guillot
Author: Zaven Arzoumanian
Author: Slavko Bogdanov
Author: Deepto Chakrabarty
Author: Keith C. Gendreau
Author: Wynn C.G. Ho ORCID iD
Author: James M. Lattimer
Author: Renee M. Ludlam
Author: Michael T. Wolff

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