A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy

Journal Article · 07 September 2021 · The Astrophysical Journal. Letters

DOI: https://doi.org/10.3847/2041-8213/ac0a81 · OSTI ID:1864772

Riley, Thomas E.  ^[1]; Watts, Anna L.  ^[2]; Ray, Paul S.  ^[3]; Bogdanov, Slavko  ^[4]; Guillot, Sebastien  ^[5]; Morsink, Sharon M.  ^[6]; Bilous, Anna V.  ^[7]; Arzoumanian, Zaven ^[8]; Choudhury, Devarshi  ^[2]; Deneva, Julia S.  ^[9]; Gendreau, Keith C.  ^[8]; Harding, Alice K.  ^[10]; Ho, Wynn C. G.  ^[11]; Lattimer, James M.  ^[12]; Loewenstein, Michael ^[13]; Ludlam, Renee M.  ^[14]; Markwardt, Craig B.  ^[8]; Okajima, Takashi  ^[8]; Prescod-Weinstein, Chanda  ^[15]; Remillard, Ronald A.  ^[16] ; Wolff, Michael T.  ^[3]; Fonseca, Emmanuel  ^[17]; Cromartie, H. Thankful  ^[18]; Kerr, Matthew  ^[3]; Pennucci, Timothy T.  ^[19]; Parthasarathy, Aditya  ^[20]; Ransom, Scott  ^[21]; Stairs, Ingrid  ^[22]; Guillemot, Lucas  ^[23]; Cognard, Ismael  ^[23]

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1. Univ. of Amsterdam (Netherlands); Stony Brook University
2. Univ. of Amsterdam (Netherlands)
3. U.S. Naval Research Lab., Washington, DC (United States)
4. Columbia Univ., New York, NY (United States)
5. IRAP, CNRS, Toulouse (France); Univ. de Toulouse (France)
6. Univ. of Alberta, Edmonton, AB (Canada)
7. ASTRON, the Netherlands Institute for Radio Astronomy, Dwingeloo (The Netherlands)
8. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
9. George Mason Univ., Washington, DC (United States); U.S. Naval Research Lab., Washington, DC (United States)
10. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
11. Haverford College, PA (United States)
12. Stony Brook Univ., NY (United States)
13. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
14. California Institute of Technology (CalTech), Pasadena, CA (United States)
15. Univ. of New Hampshire, Durham, NH (United States)
16. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
17. McGill Univ., Montreal, QC (Canada); West Virginia Univ., Morgantown, WV (United States)
18. Cornell Univ., Ithaca, NY (United States)
19. National Radio Astronomy Observatory, Charlottesville, VA (United States); Eötvös Loránd Univ., Budapest (Hungary)
20. Max Planck Inst. for Radio Astronomy, Bonn (Germany)
21. National Radio Astronomy Observatory, Charlottesville, VA (United States)
22. Univ. of British Columbia, Vancouver, BC (Canada)
23. Univ. d'Orléans/CNRS (France); Station de radioastronomie de Nançay (France)

We report on Bayesian estimation of the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, conditional on pulse-profile modeling of Neutron Star Interior Composition Explorer X-ray Timing Instrument event data. We condition on informative pulsar mass, distance, and orbital inclination priors derived from the joint North American Nanohertz Observatory for Gravitational Waves and Canadian Hydrogen Intensity Mapping Experiment/Pulsar wideband radio timing measurements of Fonseca et al. We use XMM-Newton European Photon Imaging Camera spectroscopic event data to inform our X-ray likelihood function. The prior support of the pulsar radius is truncated at 16 km to ensure coverage of current dense matter models. We assume conservative priors on instrument calibration uncertainty. We constrain the equatorial radius and mass of PSR J0740+6620 to be $${12.39}_{-0.98}^{+1.30}$$ km and $${2.072}_{-0.066}^{+0.067}$$ M_⊙ respectively, each reported as the posterior credible interval bounded by the 16% and 84% quantiles, conditional on surface hot regions that are non-overlapping spherical caps of fully ionized hydrogen atmosphere with uniform effective temperature; a posteriori, the temperature is $${\mathrm{log}}_{10}(T\,[{\rm{K}}])={5.99}_{-0.06}^{+0.05}$$ for each hot region. All software for the X-ray modeling framework is open-source and all data, model, and sample information is publicly available, including analysis notebooks and model modules in the Python language. Furthermore, our marginal likelihood function of mass and equatorial radius is proportional to the marginal joint posterior density of those parameters (within the prior support) and can thus be computed from the posterior samples.

• Research Organization: Research Foundation of New York, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: FG02-87ER40317
• OSTI ID: 1864772
• Journal Information: The Astrophysical Journal. Letters, Journal Name: The Astrophysical Journal. Letters Journal Issue: 2 Vol. 918; ISSN 2041-8205
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English