{"work":{"id":"93b505ac-6397-4f9e-9cd1-e3ae8d8bbce7","openalex_id":null,"doi":null,"arxiv_id":"2105.06979","raw_key":null,"title":"The Radius of PSR J0740+6620 from NICER and XMM-Newton Data","authors":null,"authors_text":"M. C. Miller, F. K. Lamb, A. J. Dittmann, S. Bogdanov, Z. Arzoumanian, K. C. Gendreau","year":2021,"venue":"astro-ph.HE","abstract":"PSR J0740$+$6620 has a gravitational mass of $2.08\\pm 0.07~M_\\odot$, 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 $\\sim 2~M_\\odot$ 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 $\\sim 1.5-3$ times nuclear saturation density. For a given framework, when all measurements are included the radius of a $1.4~M_\\odot$ neutron star is known to $\\pm 4$% (68% credibility) and the radius of a $2.08~M_\\odot$ neutron star is known to $\\pm 5$%. The full radius range that spans the $\\pm 1\\sigma$ credible intervals of all the radius estimates in the three frameworks is $12.45\\pm 0.65$ km for a $1.4~M_\\odot$ neutron star and $12.35\\pm 0.75$ km for a $2.08~M_\\odot$ neutron star.","external_url":"https://arxiv.org/abs/2105.06979","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-05-22T18:21:55.553597+00:00","pith_arxiv_id":"2105.06979","created_at":"2026-05-09T06:35:38.415572+00:00","updated_at":"2026-05-22T18:21:55.553597+00:00","title_quality_ok":true,"display_title":"The Radius of PSR J0740+6620 from NICER and XMM-Newton Data","render_title":"The Radius of PSR J0740+6620 from NICER and XMM-Newton Data"},"hub":{"state":{"work_id":"93b505ac-6397-4f9e-9cd1-e3ae8d8bbce7","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":26,"external_cited_by_count":null,"distinct_field_count":4,"first_pith_cited_at":"2025-04-26T01:56:18+00:00","last_pith_cited_at":"2026-05-18T17:53:13+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-05-31T04:41:56.492963+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":10}],"polarity_counts":[{"context_polarity":"background","n":10}],"runs":{},"summary":{},"graph":{},"authors":[]}}