Simulating pasta phases by molecular dynamics and cold atoms --- Formation in supernovae and superfluid neutrons in neutron stars

Simulation of Transitions between "Pasta" Phases in Dense Matter

Calculations of equilibrium properties of dense matter predict that at subnuclear densities nuclei can be rodlike or slablike. To investigate whether transitions between phases with non-spherical nuclei can occur during the collapse of a star, we perform quantum molecular dynamic simulations of the compression of dense matter. We have succeeded in simulating the transitions between rodlike and slablike nuclei and between slablike nuclei and cylindrical bubbles. Our results strongly suggest that non-spherical nuclei can be formed in the inner cores of collapsing stars.

The cooling of the Cassiopeia A neutron star as a probe of the nuclear symmetry energy and nuclear pasta

X-ray observations of the neutron star in the Cas A supernova remnant over the past decade suggest the star is undergoing a rapid drop in surface temperature of $\approx$ $2-5.5\%$. One explanation suggests the rapid cooling is triggered by the onset of neutron superfluidity in the core of the star, causing enhanced neutrino emission from neutron Cooper pair breaking and formation (PBF). Using consistent neutron star crust and core equations of state (EOSs) and compositions, we explore the sensitivity of this interpretation to the density dependence of the symmetry energy $L$ of the EOS used, …

模拟具有超流涡旋的中子星壳层的新分子动力学方法

New Molecular Dynamics Methods for Simulating Neutron Star Crusts with Superfluid Vortices

本文提出新的分子动力学方法研究中子星壳层与超流涡旋的相互作用，发现当钉扎力与库仑力相当时会出现晶格夹带新现象，为理解壳层弹性演化提供依据。

自转减慢中子星中的超流河流

Superfluid Rivers in Spinning-down Neutron Stars

该研究模拟自转减慢中子星中涡旋阵列的变形，发现马格努斯力与钉扎力将其压缩成涡旋薄片或环面，形成携带角动量的超流河流。

Nuclear matter superfluidity in an effective hadronic field model with excluded volume corrections

Properties of the 1S0 superfluid phase are studied for symmetric nuclear matter at finite temperature. It is described within a covariant hadronic field model, of the sigma-omega type, with addition of density dependent correlations simulating effects due to finite extension of nucleons. The model is solved in a selfconsistent Hartree-Bogoliubov approach, assuming instantaneous interactions in the superfluid phase. A comparison with the results obtained from several hadronic field models is done. Main characteristics of our description of the superfluid gap are in qualitative agreement with so…

Dense Matter and Neutron Stars: Some Basic Notions

A number of properties of dense matter can be understood semiquantitatively in terms of simple physical arguments. We begin with the outer parts of neutron stars, and consider the density at which pressure ionization occurs, the density at which electrons become relativistic, the density at which neutrons drip out of nuclei, and the size of the equilibrium nucleus in dense matter. Subsequently, we treat the so-called "pasta" phases expected to occur at densities just below the density at which the transition from the crust to the liquid core of a neutron star occurs. We then consider aspects o…

Simulating dense QCD matter with ultracold atomic boson-fermion mixtures

We delineate, as an analog of two-flavor dense quark matter, the phase structure of a many-body mixture of atomic bosons and fermions in two internal states with a tunable boson-fermion attraction. The bosons b correspond to diquarks, and the fermions f to unpaired quarks. For weak b-f attraction, the system is a mixture of a Bose-Einstein condensate and degenerate fermions, while for strong attraction composite b-f fermions N, analogs of the nucleon, are formed, which are superfluid due to the N-N attraction in the spin-singlet channel. We determine the symmetry breaking patterns at finite te…

Constraints on the symmetry energy from observational probes of the neutron star crust

A number of observed phenomena associated with individual neutron star systems or neutron star populations find explanations in models in which the neutron star crust plays an important role. We review recent work examining the sensitivity to the slope of the symmetry energy $L$ of such models, and constraints extracted on $L$ from confronting them with observations. We focus on six sets of observations and proposed explanations: (i) The cooling rate of the neutron star in Cassiopeia A, confronting cooling models which include enhanced cooling in the nuclear pasta regions of the inner crust, (…

中子星的内壳：液滴模型中的多态性与超导性

Inner crust of neutron stars: Polymorphism and superconductivity in the liquid drop model

本文基于手征有效场理论的液滴模型，计算了中子星内壳核物质相的内能，证实了晶体多态性，并发现曲率修正显著改变基态与相变密度，同时揭示了千层面相中超导机制的交叉及磁应力特征。

中子星内壳层中涡旋钉扎能的微观计算

Microscopic calculation of the pinning energy of a vortex in the inner crust of a neutron star

本文采用轴向形变 Hartree-Fock-Bogolyubov 方法微观计算中子星内壳层涡旋结构，以核–涡旋结合能表征钉扎能，并得到与既往结果一致的介观钉扎力。