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arXiv 2407.09446astro-ph.HEgr-qcnucl-th
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中子-夸克星:致密星状态方程高密度部分可行替代方案的辨识

Neutron-quark stars: Discerning viable alternatives for the higher-density part of the equation of state of compact stars

Sudipta Hensh, Yong-Jia Huang, Toru Kojo, Luca Baiotti, Kentaro Takami, Shigehiro Nagataki, Hajime Sotani

AI总结:

本研究利用广义相对论数值模拟双中子星并合,探讨了向夸克物质转变的QHC与1PT场景,提出中子-夸克星概念,发现通过引力波可区分QHC与强子模型,并揭示了并合后引力波能量与主导频率的稳健线性关联。

摘要:

我们利用包含强子与混合状态方程(EOS)的广义相对论数值模拟研究了双中子星(BNS)并合,并结合了最新的观测与理论约束。我们探讨了向夸克物质转变的两种可行场景:夸克-强子交叉(QHC)或强一阶相变(1PT)。为区分不同模型,我们将中子-夸克星(NQS)定义为夸克效应在低于已观测最低中子星质量时即出现的构型。传统“混合星”或许能通过质量-半径测量与纯强子构型区分,但NQS的质量-半径关系与纯强子模型相似,强子与夸克之间没有明显边界。NQS这一名称有效体现了QHC场景中强子与夸克间相界的缺失。结果表明,若同时观测到旋近与并合后引力波(GW),QHC模型可与强子模型区分。具体而言,主导的并合后频率($f_2$)往往低于具有相同潮汐形变率($Λ$)的强子模型。我们还首次对并合前恒星已含夸克物质的BNS并合进行了广义相对论模拟。这些模拟涉及在1.8倍核饱和密度下的强一阶相变(1PT),随后是硬夸克EOS。最后,我们确定了并合后辐射的总GW能量与$f_2$频率间的稳健线性关联。值得注意的是,无论是否存在夸克,该关系均成立。

英文摘要:

We investigate binary neutron star (BNS) mergers using general-relativistic numerical simulations with hadronic and hybrid equations of state (EOSs), incorporating the latest observations and theoretical constraints. We address two viable scenarios for the transition to quark matter: a quark-hadron crossover (QHC) or a strong first-order phase transition (1PT). To distinguish between different models, we define neutron-quark stars (NQS) as configurations where quark effects emerge at masses below the lowest observed neutron-star mass. While traditional "hybrid stars" may be distinguished by purely hadronic configurations through mass-radius measurements, the mass-radius relations of NQSs resemble those of purely hadronic models, with no sharp boundary between hadrons and quarks. The name NQS effectively captures the absence of a phase boundary between hadrons and quarks in QHC scenarios. Our results indicate that QHC models can be distinguished from hadronic ones if both the inspiral and postmerger gravitational waves (GWs) are observed. In particular, the dominant postmerger frequency ($f_2$) tends to be lower than in hadronic models with the same tidal deformability ($Λ$). We also present the first general-relativistic simulations of BNS mergers where the stars already contain quark matter before merging. These involve a strong first-order phase transition (1PT) at 1.8 times nuclear saturation density, followed by a stiff quark EOS. Finally, we identify a robust linear correlation between the total GW energy emitted after the merger and the $f_2$ frequency. Remarkably, this relation holds regardless of the quark presence.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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