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تسجيل مستخدم جديدTowards Understanding Astrophysical Effects of Nuclear Symmetry Energy
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Determining the Equation of State (EOS) of dense neutron-rich nuclear matter is a shared goal of both nuclear physics and astrophysics. Except possible phase transitions, the density dependence of nuclear symmetry esym is the most uncertain part of the EOS of neutron-rich nucleonic matter especially at supra-saturation densities. Much progresses have been made in recent years in predicting the symmetry energy and understanding why it is still very uncertain using various microscopic nuclear many-body theories and phenomenological models. Simultaneously, significant progresses have also been made in probing the symmetry energy in both terrestrial nuclear laboratories and astrophysical observatories. In light of the GW170817 event as well as ongoing or planned nuclear experiments and astrophysical observations probing the EOS of dense neutron-rich matter, we review recent progresses and identify new challenges to the best knowledge we have on several selected topics critical for understanding astrophysical effects of the nuclear symmetry energy.
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In the framework of the relativistic mean field model with Thomas-Fermi approximation, we study the structures of low density nuclear matter in a three-dimensional geometry with reflection symmetry. The numerical accuracy and efficiency are improved
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A thorough understanding of properties of neutron stars requires both a reliable knowledge of the equation of state (EOS) of super-dense nuclear matter and the strong-field gravity theories simultaneously. To provide information that may help break t
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The density dependence of the nuclear symmetry energy is inspected using the Statistical Multifragmentation Model with Skyrme effective interactions. The model consistently considers the expansion of the fragments volumes at finite temperature at the
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New observational data of neutron stars since GW170817 have helped improve our knowledge about nuclear symmetry energy especially at high densities. We have learned particularly: (1) The slope parameter $L$ of nuclear symmetry energy at saturation de
nsity $rho_0$ of nuclear matter from 24 new analyses is about $Lapprox 57.7pm 19$ MeV at 68% confidence level consistent with its fiducial value, (2) The curvature $K_{rm{sym}}$ from 16 new analyses is about $K_{rm{sym}}approx -107pm 88$ MeV, (3) The magnitude of nuclear symmetry energy at $2rho_0$, i.e. $E_{rm{sym}}(2rho_0)approx 51pm 13$ MeV at 68% confidence level, has been extracted from 9 new analyses of neutron star observables consistent with 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 do not provide tight constraints on nuclear symmetry energy at densities above about $2rho_0$, the lower radius boundary $R_{2.01}=12.2$ km from NICERs very recent observation of PSR J0740+6620 of mass $2.08pm 0.07$ $M_{odot}$ and radius $R=12.2-16.3$ km at 68% confidence level sets a tight lower limit for nuclear symmetry energy at densities above $2rho_0$, (5) Bayesian inferences of nuclear symmetry energy using models encapsulating a first-order hadron-quark phase transition from observables of canonical neutron stars indicate that the phase transition shift appreciably both the $L$ and $K_{rm{sym}}$ to higher values but with larger uncertaintie , (6) The high-density behavior of nuclear symmetry energy affects significantly the minimum frequency necessary to rotationally support GW190814s secondary component of mass (2.50-2.67) $M_{odot}$ as the fastest and most massive pulsar discovered so far.
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