A General, Scale-independent Description of the Sound Speed in Neutron Stars

Ecker, Christian; Rezzolla, Luciano

doi:10.3847/2041-8213/ac8674

Cited by 35 publications

(10 citation statements)

References 49 publications

(66 reference statements)

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“…For γ and , we find good quantitative agreement with previous results, with the inner cores of maximally massive stars exhibiting conformalized behavior with high credence. For all three quantities, our results as functions of M / M TOV are moreover in good agreement with recent works 22 , 38 , 39 , 42 , 69 , 70 , with the approach towards conformal behavior as M → M TOV clearly visible. Finally, from the γ vs. panels, we observe that the majority of probability weight for M TOV stars that lies outside the gray region resides at small values of γ and .…”

Section: Resultssupporting

confidence: 92%

Strongly interacting matter exhibits deconfined behavior in massive neutron stars

Annala,

Gorda,

Hirvonen

et al. 2023

Nat Commun

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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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Section: Resultssupporting

confidence: 92%

Strongly interacting matter exhibits deconfined behavior in massive neutron stars

Annala,

Gorda,

Hirvonen

et al. 2023

Nat Commun

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show abstract

“…with n s ≈ 0.16 fm −3 . The interaction between the astrophysical and the QCD constraints has also been studied, showing that the QCD input leads to a softening of the EoS at the highest densities reached inside the cores of stable NSs [3,4,33,[45][46][47][48][49] (cf. [50]).…”

Section: Jhep06(2023)002mentioning

confidence: 99%

Bayesian uncertainty quantification of perturbative QCD input to the neutron-star equation of state

Gorda

Komoltsev

Kurkela

et al. 2023

J. High Energ. Phys.

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The equation of state of neutron-star cores can be constrained by requiring a consistent connection to the perturbative Quantum Chromodynamics (QCD) calculations at high densities. The constraining power of the QCD input depends on uncertainties from missing higher-order terms, the choice of the unphysical renormalization scale, and the reference density where QCD calculations are performed. Within a Bayesian approach, we discuss the convergence of the perturbative QCD series, quantify its uncertainties at high densities, and present a framework to systematically propagate the uncertainties down to neutron-star densities. We find that the effect of the QCD input on the neutron-star inference is insensitive to the various unphysical choices made in the uncertainty estimation.

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“…The EOS constraints from kilonova observations have also been investigated (e.g., Margalit & Metzger 2017;Radice et al 2018b;Coughlin et al 2019;Breschi et al 2021;Holmbeck et al 2022). A group of EOSs from different nuclear many-body frameworks or the parameterizations of EOS such as piecewise polytropes (De et al 2018;Most et al 2018;Ecker & Rezzolla 2022), or spectral parameterization (Lindblom 2010;Koliogiannis & Moustakidis 2019) were usually adopted, allowing the study only on the pressure-versus-density function, but not on the physical properties of nuclear matter.…”

Section: Introductionmentioning

confidence: 99%

A Bayesian Inference of a Relativistic Mean-field Model of Neutron Star Matter from Observations of NICER and GW170817/AT2017gfo

Zhu

Liu

2023

ApJ

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Observations of optical and near-infrared counterparts of binary neutron star mergers not only enrich our knowledge about the abundance of heavy elements in the universe and help reveal the remnant object just after the merger, which is generally known, but can also effectively constrain the dense properties of the nuclear matter and the equation of state (EOS) in the interior of the merging stars. Following the relativistic mean-field description of nuclear matter, we perform a Bayesian inference of the EOS and the properties of the nuclear matter using the first multi-messenger event GW170817/AT2017gfo, together with the NICER mass–radius measurements of pulsars. The kilonova is described by a radiation-transfer model with the dynamical ejecta, and light curves connect with the EOS through the quasi-universal relations between the properties of the ejecta (the ejected mass, velocity, opacity, or electron fraction) and binary parameters (the mass ratio and reduced tidal deformability). It is found that the posterior distributions of the reduced tidal deformability from the AT2017gfo analysis display a bimodal structure, with the first peak enhanced by the GW170817 data, leading to slightly softened posterior EOSs, while the second peak cannot be achieved by a nuclear EOS with saturation properties in their empirical ranges. The inclusion of NICER data results in a stiffened EOS posterior because of the massive pulsar PSR J0740+6620. We provide the results at nuclear saturation density for the nuclear incompressibility, the symmetry energy, and its slope, as well as the nucleon effective mass, from our analysis of the observational data.

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A General, Scale-independent Description of the Sound Speed in Neutron Stars

Cited by 35 publications

References 49 publications

Strongly interacting matter exhibits deconfined behavior in massive neutron stars

Strongly interacting matter exhibits deconfined behavior in massive neutron stars

Bayesian uncertainty quantification of perturbative QCD input to the neutron-star equation of state

A Bayesian Inference of a Relativistic Mean-field Model of Neutron Star Matter from Observations of NICER and GW170817/AT2017gfo

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