New insights into supradense matter from dissecting scaled stellar structure equations

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 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...

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Main Authors: Bao-Jun Cai, Bao-An Li
Format: Article
Language:English
Published: Frontiers Media S.A. 2024-12-01
Series:Frontiers in Astronomy and Space Sciences
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Online Access:https://www.frontiersin.org/articles/10.3389/fspas.2024.1502888/full
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author Bao-Jun Cai
Bao-An Li
author_facet Bao-Jun Cai
Bao-An Li
author_sort Bao-Jun Cai
collection DOAJ
description 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 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 perturbatively anatomizing 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 the properties (e.g., density profiles of the sound speed squared s2=dP/dε and trace anomaly Δ=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 MNS, radius R, and compactness ξ≡MNS/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.
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spelling doaj-art-e3a5f1f49dc94a19b76f245885092d8a2025-08-20T02:50:00ZengFrontiers Media S.A.Frontiers in Astronomy and Space Sciences2296-987X2024-12-011110.3389/fspas.2024.15028881502888New insights into supradense matter from dissecting scaled stellar structure equationsBao-Jun Cai0Bao-An Li1Quantum Machine Learning Laboratory, Shadow Creator Inc., Shanghai, ChinaDepartment of Physics and Astronomy, Texas A&M University-Commerce, Commerce, TX, United StatesThe strong-field gravity in general relativity (GR) realized in neutron stars (NSs) renders the equation of state (EOS) P(ε) of supradense neutron star 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 perturbatively anatomizing 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 the properties (e.g., density profiles of the sound speed squared s2=dP/dε and trace anomaly Δ=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 MNS, radius R, and compactness ξ≡MNS/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.https://www.frontiersin.org/articles/10.3389/fspas.2024.1502888/fullequation of statesupradense matterneutron starTolman–Oppenheimer–Volkoff equationsprinciple of causalityspecial relativity
spellingShingle Bao-Jun Cai
Bao-An Li
New insights into supradense matter from dissecting scaled stellar structure equations
Frontiers in Astronomy and Space Sciences
equation of state
supradense matter
neutron star
Tolman–Oppenheimer–Volkoff equations
principle of causality
special relativity
title New insights into supradense matter from dissecting scaled stellar structure equations
title_full New insights into supradense matter from dissecting scaled stellar structure equations
title_fullStr New insights into supradense matter from dissecting scaled stellar structure equations
title_full_unstemmed New insights into supradense matter from dissecting scaled stellar structure equations
title_short New insights into supradense matter from dissecting scaled stellar structure equations
title_sort new insights into supradense matter from dissecting scaled stellar structure equations
topic equation of state
supradense matter
neutron star
Tolman–Oppenheimer–Volkoff equations
principle of causality
special relativity
url https://www.frontiersin.org/articles/10.3389/fspas.2024.1502888/full
work_keys_str_mv AT baojuncai newinsightsintosupradensematterfromdissectingscaledstellarstructureequations
AT baoanli newinsightsintosupradensematterfromdissectingscaledstellarstructureequations