Astrophysical Implications on Hyperon Couplings and Hyperon Star Properties with Relativistic Equations of States

Sun, Xiangdong; Miao, Zhiqiang; Sun, Bao Yuan; Li, Ang

doi:10.3847/1538-4357/ac9d9a

“…For the preferred emission pattern and viewing geometry, the mass and radius inferred by R19 for PSR J0030+0451 was M 1.34 0.16 0.15 -+  and 12.71 1.19 1.14 -+ km, where the uncertainties, here and throughout this work, are specified at approximately the 16% and 84% quantiles in the 1D marginal posterior (for comparison, Miller et al 2019 km). The mass and radius posteriors have since been used in a variety of studies to constrain the EoS (see, for example, Raaijmakers et al 2021;Tang et al 2021;Biswas 2022;Sabatucci et al 2022;Rutherford et al 2023;Sun et al 2023). The fact that PSR J0030+0451 has an inferred radius similar to that inferred for the ∼2.1 M e pulsar PSR J0740+6620 (Fonseca et al 2021;Miller et al 2021;Riley et al 2021;Salmi et al 2022), despite the much lower inferred mass, is particularly notable (Raaijmakers et al 2021).…”

Section: Introductionmentioning

confidence: 99%

An Updated Mass–Radius Analysis of the 2017–2018 NICER Data Set of PSR J0030+0451

Vinciguerra,

Salmi,

Watts

et al. 2024

ApJ

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In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterizing dense matter. Two independent analyses found a mass of ∼1.3–1.4 M ⊙ and a radius of ∼13 km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyze, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and also jointly analyze XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multimodal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding constraints disfavors the main solutions found previously, in favor of the new and more complex models. These have inferred masses and radii of ∼[1.4 M ⊙, 11.5 km] and ∼[1.7 M ⊙, 14.5 km], depending on the assumed model. They display configurations that do not require the two hot spots generating the observed X-rays to be on the same hemisphere, nor to show very elongated features, and point instead to the presence of temperature gradients and the need to account for them.

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“…For in-stance, a comprehensive macroscopic-microscopic model was developed to evaluate the total energies of eveneven nuclei with proton numbers ranging from 8 to 110 [62]. Even with the appearance of a hyperon [63,64], larger maximum masses of neutron stars could be obtained with DD-LZ1 than with several other RMF parameter sets, providing the possibility that the secondary object observed in GW190814 is a neutron star [65−67]. Utilizing the Thomas-Fermi approximation, different microscopic structures of nonuniform nuclear matter were calculated for the crust of neutron stars, and a unified equation of state was established in a vast density range [68,69].…”

Section: Nnmentioning

confidence: 99%

Density-dependent relativistic mean field approach and its application to single-Λ hypernuclei in oxygen hyperisotopes*

Ding 丁,

Yang 杨,

Sun 孙

2023

Chinese Phys. C

1

0

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The in-medium feature of nuclear force, which includes both nucleon-nucleon ( ) and hyperon-nucleon ( ) interactions, impacts the description of single-Λ hypernuclei. With the alternated mass number or isospin of hypernuclei, such effects may be unveiled by analyzing the systematic evolution of the bulk and single-particle properties. From a density-dependent meson-nucleon/hyperon coupling perspective, a new effective interaction in the covariant density functional (CDF) theory, namely, DD-LZ1- , is obtained by fitting the experimental data of Λ separation energies for several single-Λ hypernuclei. It is then used to study the structure and transition properties of single-Λ hypernuclei in oxygen hyperisotopes, in comparison with those determined using several selected CDF Lagrangians. A discrepancy is explicitly observed in the isospin evolution of spin-orbit splitting with various effective interactions, which is attributed to the divergence of the meson-hyperon coupling strengths with increasing density. In particular, the density-dependent CDFs introduce an extra contribution to reduce the value but enhance the isospin dependence of the splitting, which originates from the rearrangement terms of Λ self-energies. In addition, the characteristics of hypernuclear radii are studied along the isotopic chain. Owing to the impurity effect of the Λ hyperon, a size shrinkage is observed in the matter radii of hypernuclei compared with the cores of normal nuclei, and its magnitude is further elucidated to correlate with the incompressibility of nuclear matter. Moreover, there is a sizable model-dependent trend in which the Λ hyperon radii evolve with neutron number, which is decided partly by the in-medium interactions and core polarization effects.

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“…Radio timing measurements of high pulsar masses (Antoniadis et al 2013;Arzoumanian et al 2018;Cromartie et al 2020;Fonseca et al 2021;Shamohammadi et al 2023) and gravitational-wave (GW) measurements of tidal deformability from neutron star binary mergers (Abbott et al 2019(Abbott et al , 2020 have now been supplemented by measurements of neutron star mass and radius for X-ray pulsars using data from the Neutron Star Interior Composition Explorer (NICER; Gendreau et al 2016). These astrophysical measurements have been used in various analyses, often in combination with constraints from nuclear theory and laboratory experiments, to place limits on the properties of neutron-rich matter, possible quark or hyperon phases in neutron star cores, and the presence of dark matter in and around neutron stars (see, e.g., Legred et al 2021;Miller et al 2021;Raaijmakers et al 2021a;Biswas 2022;Huth et al 2022;Miao et al 2022;Annala et al 2023;Giangrandi et al 2023;Rutherford et al 2023;Sun et al 2023;Takátsy et al 2023;Koehn et al 2024;Kurkela et al 2024;Pang et al 2024;Shakeri & Karkevandi 2024).…”

Section: Introductionmentioning

confidence: 99%

Constraining the Dense Matter Equation of State with New NICER Mass–Radius Measurements and New Chiral Effective Field Theory Inputs

Rutherford,

Mendes,

Svensson

et al. 2024

ApJL

8

0

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Pulse profile modeling of X-ray data from the Neutron Star Interior Composition Explorer is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory (χEFT), and masses and tidal deformabilities inferred from gravitational-wave detections of binary neutron star mergers, this has led to a steady improvement in our understanding of the dense matter equation of state (EOS). Here, we consider the impact of several new results: the radius measurement for the 1.42 M ⊙ pulsar PSR J0437−4715 presented by Choudhury et al., updates to the masses and radii of PSR J0740+6620 and PSR J0030+0451, and new χEFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions—a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS)—we find the radius of a 1.4 M ⊙ (2.0 M ⊙) neutron star to be constrained to the 95% credible ranges 12.28 − 0.76 + 0.50 km ( 12.33 − 1.34 + 0.70 km) for the PP model and 12.01 − 0.75 + 0.56 km ( 11.55 − 1.09 + 0.94 km) for the CS model. The maximum neutron star mass is predicted to be 2.15 − 0.16 + 0.14 M ⊙ and 2.08 − 0.16 + 0.28 M ⊙ for the PP and CS models, respectively. We explore the sensitivity of our results to different orders and different densities up to which χEFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference R 2.0 − R 1.4 of the radius of 2 M ⊙ and 1.4 M ⊙ neutron stars within our EOS inference.

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Astrophysical Implications on Hyperon Couplings and Hyperon Star Properties with Relativistic Equations of States

Cited by 19 publications

References 88 publications

An Updated Mass–Radius Analysis of the 2017–2018 NICER Data Set of PSR J0030+0451

An Updated Mass–Radius Analysis of the 2017–2018 NICER Data Set of PSR J0030+0451

Density-dependent relativistic mean field approach and its application to single-Λ hypernuclei in oxygen hyperisotopes*

Constraining the Dense Matter Equation of State with New NICER Mass–Radius Measurements and New Chiral Effective Field Theory Inputs

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