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

  • M. C. Miller
  • , F. K. Lamb
  • , A. J. Dittmann
  • , S. Bogdanov
  • , Z. Arzoumanian
  • , K. C. Gendreau
  • , S. Guillot
  • , W. C.G. Ho
  • , J. M. Lattimer
  • , M. Loewenstein
  • , S. M. Morsink
  • , P. S. Ray
  • , M. T. Wolff
  • , C. L. Baker
  • , T. Cazeau
  • , S. Manthripragada
  • , C. B. Markwardt
  • , T. Okajima
  • , S. Pollard
  • , I. Cognard
  • H. T. Cromartie, E. Fonseca, L. Guillemot, M. Kerr, A. Parthasarathy, T. T. Pennucci, S. Ransom, I. Stairs
  • University of Maryland, College Park
  • University of Illinois at Urbana-Champaign
  • Columbia University
  • NASA Goddard Space Flight Center
  • Institute de Recherche en Astrophysique et Planétologie
  • Université de Toulouse
  • Haverford College
  • University of Alberta
  • Naval Research Laboratory
  • Université d'Orléans
  • CNRS
  • Cornell University
  • McGill University
  • West Virginia University
  • Max Planck Institute for Radio Astronomy
  • National Science Foundation
  • Eötvös Loránd University
  • University of British Columbia

Research output: Contribution to journalArticlepeer-review

1152 Scopus citations

Abstract

PSR J0740+6620 has a gravitational mass of 2.08 ± 0.07 M o˙, 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 13.7-1.5+2.6 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 o˙ 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 o˙ neutron star is known to ±4% (68% credibility) and the radius of a 2.08 M o˙ 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 o˙ neutron star and 12.35 ± 0.75 km for a 2.08 M o˙ neutron star.

Original languageEnglish
Article numberL28
JournalAstrophysical Journal Letters
Volume918
Issue number2
DOIs
StatePublished - Sep 10 2021

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