绚丽的超新星遗迹

<正>宇宙中的天体,生与死总是相依相伴。比如,中小质量恒星的死,伴随着白矮星和行星状星云的生;大质量恒星的死,伴随着中子星、黑洞和超新星遗迹的生。超新星遗迹,是大质量恒星死亡前发生灾难性的爆炸后,原来恒星包层中的物质被抛射到星际空间而形成的,而爆发后在中心留下来的核心就成了中子星或黑洞。超新星遗迹的诞生超新星遗迹的诞生,伴随着星体的剧烈爆发。这种爆发主要有两大类,一类是核燃烧导致的超新星爆发,另一类是常说的引力坍缩型超新星爆发。     

星际物质对动态球对称带电黑洞非热辐射影响的研究

恒星内部依次进行的核反应促使恒星不断地演化 ,恒星演化到晚期的归宿将成为白矮星、中子星或黑洞 ,如果核能耗尽的晚期恒星经过物质抛射过程后的质量大于 3倍太阳质量 ,则简并的中子压力也将抵档不住引力的坍缩 ,星体将继续坍缩成黑洞 .自 1 974年Ｈａｗｋｉｎｇ提出任何黑洞都会产生辐射以来 ,人们为了探测黑洞进行了一系列的研究工作[1～ 4] .在理论研究方面 ,对稳态黑洞和动态黑洞的研究 ,特别是在对动态黑洞的热辐射和非热辐射研究方面取得的结果 ,促进了黑洞物理学的研究与发展 .在观测方面 ,自 2 0世纪 70年代以来 ,人们用各种可能的…     

黑洞量子理论的哲学意义

黑洞是爱因斯坦引力理论和时空结构的必然产物,是物理学中的一个奇特概念。1915年爱因斯坦提出广义相对论,为黑洞说的形成奠定了理论基础。其后德国人施瓦茨希尔计算出爱斯坦广义相对论复杂场方程的一个解:对于质量M相当于一个太阳的天体,其半径坍缩到3公里以内时,就会形成黑洞。目前,黑洞已经不仅仅是预言中的纯理论概念了;大多数天文学家和物理学家认为,宇宙中既然存在白矮星、中子星,如     

引力子质量对中子星I-Q关系的修正

近年来,研究发现中子星的转动惯量I和四极矩Q存在着一个关系式,即I-Q关系.而且,该关系式不依赖于中子星内部的物态方程,与引力理论相关.因此,对该关系式的研究可用来检验引力理论.de Rham-GabadadzeTolley(dRGT)massive gravity是一种自洽的引力子静止质量不为零的修正引力理论,是目前国际引力理论研究的热点.本论文主要基于该修正引力理论,在慢速旋转近似下,利用多方指数n=0的物态方程,计算了dRGT massive gravity中牛顿极限下的I-Q关系.我们将dRGT massive gravity与爱因斯坦引力中的I-Q关系进行比较,发现引力子质量不会影响I与Q的平方之间无量纲化后的正比关系,但会改变其比例系数.     

自引力辐射体系的熵的引力坍缩

利用李立新和刘辽导出的黑洞视界附近的辐射态方程计算了约束在一个球盒形子中的自引力辐射体系（含有中心黑洞）的熵的上限，讨论了该体系的引力坍缩的合理模式，证明了这一坍缩过程是一个熵增加过程；在坍缩过程中，整个体系的熵的上限等于具有相同质量的黑洞熵，这一结果为黑洞熵的起源提供了一个合理的解释。     

两颗恒星有可能融合吗？

<正>A:对引力波探测有所了解的读者想必知道,目前发现的引力波来自于黑洞、中子星等天体的合并。这些天体密度巨大,被形象地分类为致密天体,它们往往是普通恒星演化到核聚变反应终止、引力坍缩后的产物。那么,普通的恒星之间会不会也像这些致密天体一样发生合并现象呢?答案是肯定的。有些相距很近的双星系统之间存在物质     

核子“直接URCA”过程发生的条件和中子星的冷却机制

讨论了核子的“直接ＵＲＣＡ”过程发生的条件，发现在ＵＶ１４＋ＵＶⅡ态式描述的中子星物质中，核子的“直接ＵＲＣＡ”过程发生的条件是质子数分数必须超过０．１４；强调在中子昨丙“标准冷却”机制和“非标准冷却”机械可能同时存在；对几个没质量中子星的冷却过程的计算结果表明，引力 质量小于约１．６Ｍ的中子星核内应发生“标准冷却”过程，而在引力质量大于约１．６Ｍ的中子星核内可能存在２种冷却机制。     

宇宙中的结构形成

现代宇宙学的中心问题是宇宙中大尺度结构的形成问题.在标准等级成团结构形成理论中, 暗物质主宰着宇宙.今天所观测到的各种结构如星系、星系群和星系团,是通过引力不稳定 性形成.由于引力不稳定性,暗物质的小扰动先坍缩最终形成暗物质晕(或暗晕). 较小的 暗晕通过并合形成较大的暗晕.引力形成的结构的质量分布通常称为质量函数,由观测来确定[1-4]. Press等[5]。     

新中子星可能由恒星核演化

大质量恒星步入老年后，会产生超新星爆发，但在自身引力作用下不断坍缩的恒星核将变成什么，一直没有定论。加拿大多伦     

中子星辐射引力红移的量子真空极化修正

测量中子星表面辐射谱的引力红移被认为是探究这类致密天体基本物理特性最为直接有效的手段. 但是,脉冲星、磁星这些强磁化中子星表面的辐射红移不仅源于引力的作用, 还需要考虑星体表面的磁化等离子体以及由超强磁场所诱导的量子电动力学(quantum electrodynamics, QED) 真空极化效应对辐射的电磁作用. 运用Gordon有效度规理论研究磁化等离子体以及QED真空极化效应对星体辐射的影响. 计算结果表明, 一般情况下对辐射引力红移的修正起主要作用的是星体表面的磁化等离子体, 但在某些特定情况下, 还必须考虑QED真空极化效应的作用.     

大质量中子星可包含超子

在相对论平均场理论(RMFT)框架下考虑超子自由度, 用7个参数组计算中子星的质量, 并分析超子耦合常数对中子星最大质量的影响. 结果表明: 对应状态方程（EOS）较硬的3个参数组（NLSH,NL3,NL2）, 中子星的最大质量可达已观测到中子星PSR J0348+0432和PSR J1614-2230及双中子星合并GW170817中给出的质量, 即大质量中子星结构中可包含超子相； 随着超子耦合常数χ的增大, 状态方程变硬, 中子星最大质量增大； 当NLSH参数组的χ≥0.6时, 中子星最大质量均大于2M⊙（M⊙为太阳质量）. 因此, 合理选择状态方程较硬的参数组与较强超子耦合常数可获得大质量中子星.     

A debris disk around an isolated young neutron star

Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such 'fallback' is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation. Fallback disks could dramatically affect the early evolution of pulsars, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (> or = 10(6) years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars, suggesting the possibility of planet formation around young neutron stars.     

超子排斥势和弱吸引势对中子星性质的影响

从相对论平均场理论出发,研究了不同超子势下,超子耦合常数对中子星性质的影响．对4种不同的超子势进行了计算,计算发现,∑强排斥势和Ξ的弱吸引势都将抑制超子的产生．作者通过对不同超子势的计算得到以下结果：∑排斥势越强,状态方程越硬,其所得中子星的最大质量越大．计算得到中子星的质量为1．32～1．45M⊙（M⊙为太阳质量）,与实际观测基本符合．     

A neutron-star-driven X-ray flash associated with supernova SN 2006aj

Supernovae connected with long-duration gamma-ray bursts (GRBs) are hyper-energetic explosions resulting from the collapse of very massive stars ( approximately 40 M\circ, where M\circ is the mass of the Sun) stripped of their outer hydrogen and helium envelopes. A very massive progenitor, collapsing to a black hole, was thought to be a requirement for the launch of a GRB. Here we report the results of modelling the spectra and light curve of SN 2006aj (ref. 9), which demonstrate that the supernova had a much smaller explosion energy and ejected much less mass than the other GRB-supernovae, suggesting that it was produced by a star whose initial mass was only approximately 20 M\circ. A star of this mass is expected to form a neutron star rather than a black hole when its core collapses. The smaller explosion energy of SN 2006aj is matched by the weakness and softness of GRB 060218 (an X-ray flash), and the weakness of the radio flux of the supernova. Our results indicate that the supernova-GRB connection extends to a much broader range of stellar masses than previously thought, possibly involving different physical mechanisms: a 'collapsar' (ref. 8) for the more massive stars collapsing to a black hole, and magnetic activity of the nascent neutron star for the less massive stars.     

Soft equations of state for neutron-star matter ruled out by EXO 0748 - 676

The interiors of neutron stars contain matter at very high densities, in a state that differs greatly from those found in the early Universe or achieved in terrestrial experiments. Matter in these conditions can only be probed through astrophysical observations that measure the mass and radius of neutron stars with sufficient precision. Here I report a determination of the mass and radius of the neutron star EXO 0748 - 676 that appears to rule out all the soft equations of state of neutron-star matter. If this object is typical, then condensates and unconfined quarks do not exist in the centres of neutron stars.     

A two-solar-mass neutron star measured using Shapiro delay

Neutron stars are composed of the densest form of matter known to exist in our Universe, the composition and properties of which are still theoretically uncertain. Measurements of the masses or radii of these objects can strongly constrain the neutron star matter equation of state and rule out theoretical models of their composition. The observed range of neutron star masses, however, has hitherto been too narrow to rule out many predictions of 'exotic' non-nucleonic components. The Shapiro delay is a general-relativistic increase in light travel time through the curved space-time near a massive body. For highly inclined (nearly edge-on) binary millisecond radio pulsar systems, this effect allows us to infer the masses of both the neutron star and its binary companion to high precision. Here we present radio timing observations of the binary millisecond pulsar J1614-2230 that show a strong Shapiro delay signature. We calculate the pulsar mass to be (1.97?±?0.04)M(⊙), which rules out almost all currently proposed hyperon or boson condensate equations of state (M(⊙), solar mass). Quark matter can support a star this massive only if the quarks are strongly interacting and are therefore not 'free' quarks.     

中子星内引力能的研究

用一般静态各向同性度规研究了中子星的引力能。认为引力场对中子星质量的贡献是由于不变体积元，从而使中子星质量的定义得到澄清。     

中子星的引力质量亏损和转动质量效应

本文从Ｋｅｒｒ度规出发，推算了中子星的引力质量亏损和转动质量效应。通过和同质量的恒星的情况进行比较，进一步证明了中子星具有十分显著的狭义相对论和广义相对论效应。