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The Radius of PSR J0740+6620 from NICER and XMM-Newton Data

Journal Article · · The Astrophysical Journal. Letters
 [1];  [2];  [3];  [4];  [5];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [11];  [5];  [5];  [5];  [5];  [5];  [5];  [12] more »;  [13];  [14];  [12];  [15];  [16];  [17];  [18];  [19] « less
  1. Univ. of Maryland, College Park, MD (United States); Stony Brook University
  2. Univ. of Illinois at Urbana-Champaign, IL (United States)
  3. Univ. of Maryland, College Park, MD (United States)
  4. Columbia Univ., New York, NY (United States)
  5. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  6. IRAP, CNRS (France); Univ. de Toulouse (France)
  7. Haverford College, PA (United States)
  8. Stony Brook Univ., NY (United States)
  9. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  10. Univ. of Alberta, Edmonton, AB (Canada)
  11. U.S. Naval Research Lab., Washington, DC (United States)
  12. Univ. d'Orleans, Nancay (France); CNRS (France)
  13. Cornell Univ., Ithaca, NY (United States)
  14. McGill Univ., Montreal, QC (Canada); West Virginia Univ., Morgantown, WV (United States); Naval Research Lab., Washington, DC (United States)
  15. Naval Research Lab., Washington, DC (United States)
  16. Max-Planck-Inst. für Radioastronomie, Bonn (Germany)
  17. National Radio Astronomy Observatory, Charlottesville, VA (United States); Eötvös Loránd Univ., Budapest (Germany)
  18. National Radio Astronomy Observatory, Charlottesville, VA (United States)
  19. Univ. of British Columbia, Vancouver, BC (Canada)
PSR J0740+6620 has a gravitational mass of 2.08 ± 0.07 M, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740+6620 is 13.7$$^{+2.6}_{–1.5}$$ km (68%). We apply our measurement, combined with the previous NICER mass and radius measurement of PSR J0030+0451, the masses of two other ~2 M pulsars, and the tidal deformability constraints from two gravitational wave events, to three different frameworks for equation-of-state modeling, and find consistent results at ~1.5-5 times nuclear saturation density. For a given framework, when all measurements are included, the radius of a 1.4 M neutron star is known to ±4% (68% credibility) and the radius of a 2.08 M neutron star is known to ±5%. The full radius range that spans the ±1σ credible intervals of all the radius estimates in the three frameworks is 12.45 ± 0.65 km for a 1.4 M neutron star and 12.35 ± 0.75 km for a 2.08 M neutron star.
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:
1864768
Alternate ID(s):
OSTI ID: 23154407
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

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Equation-of-state-insensitive measure of neutron star stiffness journal August 2022

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