A Nicer View of PSR J0030+0451: Implications for the Dense Matter Equation of State

Journal Article · Tue Dec 10 00:00:00 EST 2019 · The Astrophysical Journal. Letters (Online)

DOI:https://doi.org/10.3847/2041-8213/ab451a· OSTI ID:1800653

Raaijmakers, G. ^[1]; Riley, T. E. ^[2]; Watts, A. L. ^[2]; Greif, S. K. ^[3]; Morsink, S. M. ^[4]; Hebeler, K. ^[5]; Schwenk, A. ^[6]; Hinderer, T. ^[7]; Nissanke, S. ^[7]; Guillot, S. ^[8]; Arzoumanian, Z. ^[9]; Bogdanov, S. ^[10]; Chakrabarty, D. ^[11]; Gendreau, K. C. ^[9]; Ho, W. C. G. ^[12]; Lattimer, J. M. ^[13]; Ludlam, R. M. ^[14]; Wolff, M. T. ^[15]

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1. Univ. of Amsterdam (Netherlands). Anton Pannekoek Institute for Astronomy; University of Amsterdam, The Netherlands
2. Univ. of Amsterdam (Netherlands). Anton Pannekoek Institute for Astronomy
3. Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany)
4. Univ. of Alberta, Edmonton, AB (Canada)
5. InstitutTechnische Univ. Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany)
6. Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Max-Planck-Institut für Kernphysik, Heidelberg (Germany)
7. Univ. of Amsterdam (Netherlands). Anton Pannekoek Institute for Astronomy; Univ. of Amsterdam (Netherlands). GRAPPA Institute of High-Energy Physics
8. Centre National de la Recherche Scientifique (CNRS) (France); Univ. of Toulouse (France)
9. NASA Goddard Space Flight Center, Greenbelt, MD (United States). X-Ray Astrophysics Laboratory
10. Columbia Univ., New York, NY (United States). Columbia Astrophysics Laboratory
11. Massachusetts Institute of Technology, Cambridge, MA (United States). MIT Kavli Institute for Astrophysics and Space Research
12. Haverford College, Haverford, PA (United States). Dept. of Physics and Astronomy; University of Southampton (United Kingdom). Mathematical Sciences, Physics and Astronomy, and STAG Research Centre
13. Stony Brook Univ., Stony Brook, NY (United States). Dept. of Physics and Astronomy
14. California Institute of Technology, Pasadena, CA (United States). Cahill Center for Astronomy and Astrophysics
15. U.S. Naval Research Laboratory, Washington, DC (United States). Space Science Div.

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. Additionally, 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.

• Research Organization: Research Foundation of New York, NY (United States); State Univ. of New York (SUNY), Albany, NY (United States)
• Sponsoring Organization: Deutsche Forschungsgemeinschaft (DFG); European Research Council (ERC); National Aeronautics and Space Administration (NASA); Natural Sciences and Engineering Research Council of Canada (NSERC); Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO); USDOE Office of Science (SC); USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: FG02-87ER40317
• OSTI ID: 1800653
• Alternate ID(s): OSTI ID: 1864797; OSTI ID: 22992470
• Journal Information: The Astrophysical Journal. Letters (Online), Journal Name: The Astrophysical Journal. Letters (Online) Journal Issue: 1 Vol. 887; ISSN 2041-8213
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Bayesian statistics
Millisecond pulsars
Neutron star cores
Neutron stars
Nuclear astrophysics
Pulsars
X-ray stars