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REVIEW article

Front. Astron. Space Sci.
Sec. Nuclear Physics​
Volume 11 - 2024 | doi: 10.3389/fspas.2024.1502888
This article is part of the Research Topic Strong and Weak Interactions in Compact Stars View all 3 articles

New Insights into Supradense Matter from Dissecting Scaled Stellar Structure Equations

Provisionally accepted
Bao-Jun Cai Bao-Jun Cai 1Bao-An Li Bao-An Li 2*
  • 1 Quantum Machine Learning Laboratory, Shadow Creator Inc., Shanghai 201208,China, Shanghai, China
  • 2 Texas A&M University Commerce, Commerce, United States

The final, formatted version of the article will be published soon.

    The strong-field gravity in General Relativity (GR) realized in neutron stars (NSs) renders the Equation of State (EOS) P(ε) of supradense neutron star (NS) matter to be essentially nonlinear and refines the upper bound for φ ≡ P/ε to be much smaller than the Special Relativity (SR) requirement with linear EOSs, where P and ε are respectively the pressure and energy density of the system considered. Specifically, a tight bound φ ≲ 0.374 is obtained by anatomizing perturbatively the intrinsic structures of the scaled Tolman-Oppenheimer-Volkoff (TOV) equations without using any input nuclear EOS. New insights gained from this novel analysis provide EOS-model independent constraints on properties (e.g., density profiles of the sound speed squared s 2 = dP/dε and trace anomaly ∆ = 1/3-φ) of cold supradense matter in NS cores. Using the gravity-matter duality in theories describing NSs, we investigate the impact of gravity on supradense matter EOS in NSs. In particular, we show that the NS mass M NS , radius R and its compactness ξ ≡ M NS /R scale with certain combinations of its central pressure and energy density (encapsulating its central EOS). Thus, observational data on these properties of NSs can straightforwardly constrain NS central EOSs without relying on any specific nuclear EOS-model.

    Keywords: equation of state, Supradense Matter, neutron star, Tolman-Oppenheimer-Volkoff equations, Principle of causality, special relativity, speed of sound, Generality Relativity

    Received: 27 Sep 2024; Accepted: 28 Oct 2024.

    Copyright: © 2024 Cai and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Bao-An Li, Texas A&M University Commerce, Commerce, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.