Hyperonic Stars and the Nuclear Symmetry Energy

Providência, Constança; Fortin, M.; Pais, Helena; Rabhi, Aziz

doi:10.3389/fspas.2019.00013

Cited by 54 publications

(59 citation statements)

References 115 publications

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“…The symmetry energy E sym (ρ) at suprasaturation densities and the possible hadronquark phase transition are among the most uncertain parts of the EOS of dense neutronrich matter [12,13,15,29]. Moreover, the appearance of new particles, such as ∆(1232) resonances and various hyperons, also depends strongly on the high-density behavior of nuclear symmetry energy [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59]. Since the nuclear symmetry energy will lose its physical meaning above the hadron-quark transition density, it is imperative to determine both the high-density E sym (ρ) and the properties of the hadron-quark phase transition simultaneously by using combined data from astrophysical observations and nuclear experiments.…”

Section: Introductionmentioning

confidence: 99%

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Cai²,

Wang

et al. 2021

Universe

137

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The density dependence of nuclear symmetry energy is among the most uncertain parts of the Equation of State (EOS) of dense neutron-rich nuclear matter. It is currently poorly known especially at suprasaturation densities partially because of our poor knowledge about isovector nuclear interactions at short distances. Because of its broad impacts on many interesting issues, pinning down the density dependence of nuclear symmetry energy has been a longstanding and shared goal of both astrophysics and nuclear physics. New observational data of neutron stars including their masses, radii, and tidal deformations since GW170817 have helped improve our knowledge about nuclear symmetry energy, especially at high densities. Based on various model analyses of these new data by many people in the nuclear astrophysics community, while our brief review might be incomplete and biased unintentionally, we learned in particular the following: (1) The slope parameter L of nuclear symmetry energy at saturation density ρ0 of nuclear matter from 24 new analyses of neutron star observables was about L≈57.7±19 MeV at a 68% confidence level, consistent with its fiducial value from surveys of over 50 earlier analyses of both terrestrial and astrophysical data within error bars. (2) The curvature Ksym of nuclear symmetry energy at ρ0 from 16 new analyses of neutron star observables was about Ksym≈−107±88 MeV at a 68% confidence level, in very good agreement with the systematics of earlier analyses. (3) The magnitude of nuclear symmetry energy at 2ρ0, i.e., Esym(2ρ0)≈51±13 MeV at a 68% confidence level, was extracted from nine new analyses of neutron star observables, consistent with the results from earlier analyses of heavy-ion reactions and the latest predictions of the state-of-the-art nuclear many-body theories. (4) While the available data from canonical neutron stars did not provide tight constraints on nuclear symmetry energy at densities above about 2ρ0, the lower radius boundary R2.01=12.2 km from NICER’s very recent observation of PSR J0740+6620 of mass 2.08±0.07M⊙ and radius R=12.2–16.3 km at a 68% confidence level set a tight lower limit for nuclear symmetry energy at densities above 2ρ0. (5) Bayesian inferences of nuclear symmetry energy using models encapsulating a first-order hadron–quark phase transition from observables of canonical neutron stars indicated that the phase transition shifted appreciably both L and Ksym to higher values, but with larger uncertainties compared to analyses assuming no such phase transition. (6) The high-density behavior of nuclear symmetry energy significantly affected the minimum frequency necessary to rotationally support GW190814’s secondary component of mass (2.50–2.67) M⊙ as the fastest and most massive pulsar discovered so far. Overall, thanks to the hard work of many people in the astrophysics and nuclear physics community, new data of neutron star observations since the discovery of GW170817 have significantly enriched our knowledge about the symmetry energy of dense neutron-rich nuclear matter.

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Section: Introductionmentioning

confidence: 99%

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Cai²,

Wang

et al. 2021

Universe

137

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“…Thus, the knowledge about the density dependence of nuclear symmetry energy is important for understanding measurements of both the masses and especially the radii of NSs. Moreover, the critical densities for forming hyperons (Sumiyoshi & Toki 1994;Lee 1996;Kubis & Kutschera 2003;Providência et al 2019), ∆(1232) resonances (Drago et al 2014;Cai et al 2015;Zhu et al 2016;Sahoo et al 2018;Ribes et al 2019), kaon condensation (Odrzywolek & Kutschera 2009) and the quark phase (Ditoro et al 2010;Wu & Shen 2019) are also known to depend sensitively on the high-density nuclear symmetry energy. Information about the latter is thus a prerequisite for exploring the evolution of NS matter phase diagram in the isospin dimension.…”

Section: Introductionmentioning

confidence: 99%

Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars

Wang

2019

ApJ

109

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The radius R 1.4 of neutron stars (NSs) with a mass of 1.4 M ⊙ has been extracted consistently in many recent studies in the literature. Using representative R 1.4 data, we infer high-density nuclear symmetry energy E sym (ρ) and the associated nucleon specific energy E 0 (ρ) in symmetric nuclear matter (SNM) within a Bayesian statistical approach using an explicitly isospin-dependent parametric Equation of State (EOS) for nucleonic matter. We found that: (1) The available astrophysical data can already improve significantly our current knowledge about the EOS in the density range of ρ 0 − 2.5ρ 0 . In particular, the symmetry energy at twice the saturation density ρ 0 of nuclear matter is determined to be E sym (2ρ 0 ) =39.2 +12.1 −8.2 MeV at 68% confidence level.(2) A precise measurement of the R 1.4 alone with a 4% 1σ statistical error but no systematic error will not improve much the constraints on the EOS of dense neutron-rich nucleonic matter compared to what we extracted from using the available radius data. (3) The R 1.4 radius data and other general conditions, such as the observed NS maximum mass and causality condition introduce strong correlations for the high-order EOS parameters. Consequently, the high-density behavior of E sym (ρ) inferred depends strongly on how the high-density SNM EOS E 0 (ρ) is parameterized, and vice versa. (4) The value of the observed maximum NS mass and whether it is used as a sharp cut-off for the minimum maximum mass or through a Gaussian distribution affect significantly the lower boundaries of both the E 0 (ρ) and E sym (ρ) only at densities higher than about 2.5ρ 0 .

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“…I would like to call the attention of the reader for the values of the symmetry energy slope (L 0 ), which has been extensively discussed in the last years. Although its true value is still a matter of debate, most studies indicate that it has non-negligible implications on the neutron star macroscopic properties [38,[60][61][62][63][64][65][66]. The slope can be controlled by the inclusion of the ω − ρ interaction, as can be seen in Table 2.…”

Section: The Tolman-oppenheimer-volkoff Equationsmentioning

confidence: 99%

A Neutron Star Is Born

Menezes

2021

Universe

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A neutron star was first detected as a pulsar in 1967. It is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. In fact, neutron stars are star remnants, a kind of stellar zombie (they die, but do not disappear). In the last decades, astronomical observations yielded various contraints for neutron star masses, and finally, in 2017, a gravitational wave was detected (GW170817). Its source was identified as the merger of two neutron stars coming from NGC 4993, a galaxy 140 million light years away from us. The very same event was detected in γ-ray, x-ray, UV, IR, radio frequency and even in the optical region of the electromagnetic spectrum, starting the new era of multi-messenger astronomy. To understand and describe neutron stars, an appropriate equation of state that satisfies bulk nuclear matter properties is necessary. GW170817 detection contributed with extra constraints to determine it. On the other hand, magnetars are the same sort of compact object, but bearing much stronger magnetic fields that can reach up to 1015 G on the surface as compared with the usual 1012 G present in ordinary pulsars. While the description of ordinary pulsars is not completely established, describing magnetars poses extra challenges. In this paper, I give an overview on the history of neutron stars and on the development of nuclear models and show how the description of the tiny world of the nuclear physics can help the understanding of the cosmos, especially of the neutron stars.

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Hyperonic Stars and the Nuclear Symmetry Energy

Cited by 54 publications

References 115 publications

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817

Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars

A Neutron Star Is Born

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