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arXiv 1806.09999nucl-thastro-ph.HEgr-qc
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中子星稳定性条件对物态方程的约束

Constraints on the equation of state from the stability condition of neutron stars

P. S. Koliogiannis, Ch. C. Moustakidis

摘要:

恒星的平衡和坍缩是广义相对论效应与核物质状态方程相互作用的结果,主要包括白矮星、中子星和超大质量恒星。在本工作中,我们使用了大量的实际状态方程(EoS)的中子星物质的恒星不稳定性的Eosekhar标准。我们主要关注的是从稳定构型到不稳定构型转变的临界点。这一点对应于最大中子星质量组态。我们计算,在每种情况下,由此产生的紧凑性参数,$β=GM/c^2R$,和相应的有效绝热指数,$γ_{\rm cr}$。试验功能$ξ(r)$的作用,并详细讨论。我们发现它在$γ_{\rm cr}$和$β$之间具有模型无关的关系。这一说法得到了大量EoS的有力支持,也得到了爱因斯坦场方程的解析解的证实。此外,我们还讨论了在接近不稳定极限时,最大转动速率与绝热指数之间的关系。精确的观测测量的上限的中子星的质量和相应的半径,与目前的预测,可能有助于施加约束的高密度部分的中子星状态方程。

英文摘要:

The stellar equilibrium and collapse, including mainly white dwarfs, neutron stars and supper massive stars, is an interplay between general relativistic effects and the equation of state of nuclear matter. In the present work, we use the Chandrasekhar criterion of stellar instability by employing a large number of realistic equations of state (EoS) of neutron star matter. We mainly focus on the critical point of transition from stable to unstable configuration. This point corresponds to the maximum neutron star mass configuration. We calculate, in each case, the resulting compactness parameter, $β=GM/c^2R$, and the corresponding effective adiabatic index, $γ_{\rm cr}$. The role of the trial function $ξ(r)$ is presented and discussed in details. We found that it holds a model-independent relation between $γ_{\rm cr}$ and $β$. This statement is strongly supported by the large number of EoS and it is also corroborated by using analytical solutions of the Einstein's field equations. In addition, we present and discuss the relation between the maximum rotation rate and the adiabatic index close to the instability limit. Accurate observational measurements of the upper bound of the neutron star mass and the corresponding radius, in connection with the present predictions, may help to impose constraints on the high density part of the neutron star equation of state.

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