超新星核中的非奇异—奇异夸克物质相变

最近Ｇｅｎｔｉｌｅ等研究了超新星核区从核物质到夸克物质的一级相变，沿着他们的工作，本文研究从两味夸克物质到三味夸克物质的相变过程，我们发现相变时标小于１０＾－７秒，超新星的中心温度和核区的中微子总能量明显增大，这不仅会增加超新星爆发的成功机会，而且会提高复活激波的能量，同时会影响新生中子星的冷却，核区存在Ｓｃｈｗａｒｚｓｃｈｉｌｄ对流。     

超新星核中的非奇异－奇异夸克物质相变

最近Ｇｅｎｔｉｌｅ等研究了超新星核区从核物质到夸克物质的一级相变．沿着他们的工作，本文研究从两味夸克物质到三味夸克物质的相变过程．我们发现相变时标小于１０－７秒．超新星的中心温度和核区的中微子总能量明显增大，这不仅会增加超新星爆发的成功机会，而且会提高复活激波的能量，同时会影响新生中子星的冷却．核区存在Ｓｃｈｗａｒｚｓｃｈｉｌｄ对流．     

早期中子星和夸克物质

夸克禁闭的解除与夸克物质的存在一直是物理学家极感兴趣的问题。尽管理论上已指出在超高温或超高密的条件下可以有夸克物质存在,但是由于地面实验室的条件所限,目前还不能通过实验证实这一点.宇宙中被观测到的中子星(例如crab和Vela脉冲星)的中心密度大于4倍的核物质密度,其中心温度也可以达到10~8—10~9K,于是人们希     

强磁场中e^＋eˉ→3γ过程的研究

强磁场中的电磁辐射过程与自由空间的过程有着很大的差别。本工作就是对强磁场中的ｅ＾＋ｅˉ→３γ过程严格的量子电动力学处理，得到了一般情形下的截面与湮灭率的表达式。对静止湮灭作了数值计算，并与ｅ＾＋ｅˉ→γ和ｅ＾＋ｅˉ→２γ过程作了比较。比较结果表明三光子过程在弱磁场（～１０＾８Ｔ，中子星表面磁场强度）中，对低能光子（硬Ｘ射线）的发射有着不可忽略的贡献。     

强磁场中e~＋e~－→3γ过程的研究

强磁场中的电磁辐射过程与自由空间的过程有着很大的差别．本工作就是对强磁场中的ｅ~＋ｅ~─→３γ过程作严格的量子电动力学处理，得到了一般情形下的截面与湮灭率的表达式。对静止湮灭作了数值计算，并与ｅ~＋ｅ~─→γ和ｅ~＋ｅ~─→２γ过程作了比较，比较结果表明三光子过程在强磁场（～１０~８Ｔ，中子星表面磁场强度）中，对低能光子（硬Ｘ射线）的发射有着不可忽略的贡献。     

恒星演化晚期核素K壳层连续态电子俘获过程中微子能量损失

基于Weinberg-Salam理论,考虑Coulomb效应对连续态电子气体的影响,对恒星演化晚期核素12C、16O、20Ne、24Mg、28Si和56Fe在完全电离环境下的K壳层连续态自由电子俘获过程的中微子能量损失进行了讨论.根据Beaudet、Petrosian和Salpeter (BPS)的方法所得结果与我们的结果进行了比较.结果表明:相对较高温度环境(如T9=0.1和T9=1.T9是以109 K为单位的温度),两种结果符合很好;而低温环境(如T9=0.01和T9=0.001)核素16O、20Ne、24Mg和28Si的中微子能量损失,BPS的结果比我们的结果高10～70倍,对核素12C甚至高出2个数量级.我们的研究可能对恒星演化晚期尤其是白矮星核坍塌到相对低温和中等密度阶段冷却机制的研究具有重要意义.     

中子星的热演化和磁衰减

本文研究了中子星的热演化、自转演化和磁场演化的相互影响．考虑了一个自洽模型：中子星因磁偶极辐射而自转减慢，在内部产生某些加热过程，中子星磁场通过壳层的欧姆耗散来衰减．结果表明，磁场衰减提高了加热过程的重要性；相反，加热效应减慢了磁衰减．因此可以得出，中子星的热、自转和磁场也许不是独立演化的．不仅如此，这些演化与初始条件有关，因此，人们也许可以从射电和Ｘ射线观测对脉冲星年龄、初始磁场和周期给出某些限制．     

从中子星到奇异星的转变

本文利用广义相对论数值计算研究了从不同物态的中子星到不同物志的奇异星的转变过程．对于热中子星，转变可引起很大的脉冲星周期突变，其大小取决于中子物质的物态，其时标取决于奇异物质的物态．对于冷中子星，转变可产生一类γ射线爆．     

强磁场下中子星外壳的组分和状态方程

本文计算和讨论了强磁场下由冷的催化物质组成的中子星外壳的组份和状态方程。文中考虑了晶格能和强磁场下均匀电子气体的交换能的贡献.得出结论:(1)强磁场使低密度区的状态方程变软;(2)强磁场对高密度区的状态方程几乎没有影响;(3)核质量公式对外壳的组份影响较明显.     

奇异星周围的中微子主导吸积流

为统一解释伽玛射线暴(简称伽玛暴)与暴后再活动,提出了一个新的伽玛暴中心引擎模型一“奇异星-NDAF”模型(NDAF:Neutrino Dominated Accretion Flow,中微子主导吸积流),并计算了奇异星周围NDAF的结构.与其他中心致密天体不同的是,奇异星会向吸积流反馈以中微子为载体的奇异化相变能量.不考虑NDAF与奇异星的摩擦,结果表明:奇异星周围NDAF的结构对吸积率非常敏感;当吸积率大于0.18 Mo.S-1时,“奇异星-NDAF”模型能统一解释伽玛暴与暴后再活动,这个范围大于无摩擦的“中子星-NDAF”模型能统一解释的范围;在统一解释的情形下, “奇异星-NDAF”模型湮灭总能量的分布非常宽阔,当吸积率大于0.3 M0.S--1时,湮灭总能量大于1051 erg;最后,当吸积率大于0.3 M0.S-1时,“奇异星-NDAF”模型的湮灭光度超过同等吸积率下“黑洞-NDAF”模型一个多量级,有利于解释某些光度极大的伽玛暴.     

Magnetic Field of a Neutron Star With Color Superconducting Quark Matter Core

The behaviour of the magnetic field of a neutron star with a superconducting quark matter core is investigated in the framework of the Ginzburg-Landau theory. We take into account the simultaneous coupling of the diquark condensate field to the usual magnetic and to the gluomagnetic gauge fields. We solve the Ginzburg-Landau equations by properly taking into account the boundary conditions, in particular, the gluon confinement condition. We found the distribution of the magnetic field in both the quark and hadronic phases of the neutron star and show that the magnetic field penetrates into the quark core in the form of quark vortices due to the presence of Meissner currents.     

Heating and cooling of magnetars with accreted envelopes

We study the thermal structure and evolution of magnetars as cooling neutron stars with a phenomenological heat source in an internal layer. We focus on the effect of magnetized (   B ≳ 10¹⁴  G) non-accreted and accreted outermost envelopes composed of different elements, from iron to hydrogen or helium. We discuss a combined effect of thermal conduction and neutrino emission in the outer neutron star crust and calculate the cooling of magnetars with a dipole magnetic field for various locations of the heat layer, heat rates and magnetic field strengths. Combined effects of strong magnetic fields and light-element composition simplify the interpretation of magnetars in our model: these effects allow one to interpret observations assuming less extreme (therefore, more realistic) heating. Massive magnetars, with fast neutrino cooling in their cores, can have higher thermal surface luminosity.     

High-resolution calculations of merging neutron stars – II. Neutrino emission

The remnant resulting from the merger of two neutron stars produces neutrinos in copious amounts. In this paper we present the neutrino emission results obtained via Newtonian, high-resolution simulations of the coalescence event. These simulations use three-dimensional smoothed particle hydrodynamics together with a nuclear, temperature-dependent equation of state and a multiflavour neutrino leakage scheme. We present the details of our scheme, discuss the neutrino emission results from a neutron star coalescence and compare them with the core-collapse supernova case where neutrino emission has been studied for several decades. The average neutrino energies are similar to those in the supernova case, but contrary to the latter, the luminosities are dominated by electron-type antineutrinos that are produced in the hot, neutron-rich, thick disc of the merger remnant. The cooler parts of this disc contain substantial fractions of heavy nuclei, which, however, do not influence the overall neutrino emission results significantly. Our total neutrino luminosities from the merger event are considerably lower than those found in previous investigations. This imposes constraints on the ability of neutron star mergers to produce a gamma-ray burst via neutrino annihilation. The neutrinos are emitted preferentially along the initial binary rotation axis, an event seen 'pole-on' would appear much brighter in neutrinos than a similar event seen 'edge-on'.     

奇异星壳层塌缩的数值研究

当奇异星表面的电场不足以支撑整个壳层的时候,壳层就有可能全部落入奇异核中.对这一过程的研究,可以为观测上证认奇异星提供一些可能的理论线索.数值计算表明,底部密度为-8.3×1010gcm-3,亦即质量为-3 4×10-6M(?)的壳层在约5.4×10-3s时间内塌缩到奇异核中,可导致一次持续约0.15s的爆发事件.在过程中平均每个重子释放约6.3 MeV的能量,总辐射能则可高达-1046-1047ergs.这可以用来解释宇宙中一些爆发现象.     

Pycnonuclear burning of 34Ne in accreting neutron stars

We study the pycnonuclear burning of ³⁴Ne in the inner crust of an accreting neutron star. We show that the associated energy production rate can be calculated analytically for any arbitrary temporal variability of the mass accretion rate. We argue that the theoretical time-scale for ³⁴Ne burning is currently very uncertain and ranges from a fraction of a millisecond to a few years. The fastest allowable burning may change the composition of the accreted crust while the slowest burning leads to a time-independent nuclear energy generation rate for a variable accretion. The results are important for constructing self-consistent models of the accreted crust and deep crustal heating in neutron stars which enter soft X-ray transients.