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Annala E, Gorda T, Hirvonen J, Komoltsev O, Kurkela A, Nättilä J, Vuorinen A. Strongly interacting matter exhibits deconfined behavior in massive neutron stars. Nat Commun 2023; 14:8451. [PMID: 38114461 PMCID: PMC10730725 DOI: 10.1038/s41467-023-44051-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 11/28/2023] [Indexed: 12/21/2023] Open
Abstract
Neutron-star cores contain matter at the highest densities in our Universe. This highly compressed matter may undergo a phase transition where nuclear matter melts into deconfined quark matter, liberating its constituent quarks and gluons. Quark matter exhibits an approximate conformal symmetry, predicting a specific form for its equation of state (EoS), but it is currently unknown whether the transition takes place inside at least some physical neutron stars. Here, we quantify this likelihood by combining information from astrophysical observations and theoretical calculations. Using Bayesian inference, we demonstrate that in the cores of maximally massive stars, the EoS is consistent with quark matter. We do this by establishing approximate conformal symmetry restoration with high credence at the highest densities probed and demonstrating that the number of active degrees of freedom is consistent with deconfined matter. The remaining likelihood is observed to correspond to EoSs exhibiting phase-transition-like behavior, treated as arbitrarily rapid crossovers in our framework.
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Affiliation(s)
- Eemeli Annala
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, University of Helsinki, Finland
| | - Tyler Gorda
- Technische Universität Darmstadt, Department of Physics, 64289, Darmstadt, Germany.
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany.
| | - Joonas Hirvonen
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, University of Helsinki, Finland.
| | - Oleg Komoltsev
- Faculty of Science and Technology, University of Stavanger, 4036, Stavanger, Norway.
| | - Aleksi Kurkela
- Faculty of Science and Technology, University of Stavanger, 4036, Stavanger, Norway.
| | - Joonas Nättilä
- Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY, 10010, USA.
- Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY, 10027, USA.
| | - Aleksi Vuorinen
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014, University of Helsinki, Finland.
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