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arXiv 2207.13613astro-ph.HEastro-ph.IMgr-qcnucl-th
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质量大于 $0.98M_{\rm TOV}$ 的中子星中可能存在新状态

Plausible presence of new state in neutron stars with masses above $0.98M_{\rm TOV}$

Ming-Zhe Han, Yong-Jia Huang, Shao-Peng Tang, Yi-Zhong Fan

AI总结:

结合多信使数据与前沿理论,利用贝叶斯非参数神经网络模型无关地研究中子星状态方程,发现极高中子星内部声速存在非单调峰值,表明质量大于约0.98倍最大质量的中子星内部很可能存在夸克物质组成的奇异核心。

摘要:

我们通过结合 GW170817、PSR J0030+0451、PSR J0740+6620 的多信使数据以及最前沿的理论进展,包括来自手征有效场理论($χ$EFT)和微扰量子色动力学(pQCD)计算的信息,研究中子星(NS)的状态方程(EOS)。利用嵌入在贝叶斯非参数推断中的单层前馈神经网络模型对各种结构进行采样的优势,以模型无关的方式探索了中子星物质声速 $c_{\rm s}$ 的结构。研究发现,峰值结构在 $c_{\rm s}^2$ 后验分布中很常见,位于 $2.4-4.8ρ_{\rm sat}$(核饱和密度)处,且在 90% 的置信度下 $c_{\rm s}^2$ 超过了 ${c^{2}}/{3}$。这种非单调行为表明,在质量极大的中子星内部存在偏离强子物质的证据。假设新/奇异状态的特征是比典型的强子模型甚至比超子更软,我们发现对于引力质量大于约 $0.98M_{\rm TOV}$ 的中子星,可能存在一个相当大的($\geq 10^{-3}M_\odot$)奇异核心(很可能由夸克物质组成),其中 $M_{\rm TOV}$ 代表非旋转冷中子星的最大引力质量。推断出的 $M_{\rm TOV} = 2.18^{+0.27}_{-0.13}M_\odot$(90% 置信度)与假设合并后形成临时超大质量中子星残骸时,独立使用 GW170817/GRB 170817A/AT2017gfo 估算的 $2.17^{+0.15}_{-0.12}M_\odot$ 值高度一致。PSR J0740+6620 是迄今为止探测到的最大质量中子星,其拥有奇异核心的概率约为 0.36。

英文摘要:

We investigate the neutron star (NS) equation of state (EOS) by incorporating multi-messenger data of GW170817, PSR J0030+0451, PSR J0740+6620, and state-of-the-art theoretical progresses, including the information from chiral effective field theory ($χ$EFT) and perturbative quantum chromodynamics (pQCD) calculation. Taking advantage of the various structures sampling by a single-layer feed-forward neural network model embedded in the Bayesian nonparametric inference, the structure of NS matter's sound speed $c_{\rm s}$ is explored in a model-agnostic way. It is found that a peak structure is common in the $c_{\rm s}^2$ posterior, locating at $2.4-4.8ρ_{\rm sat}$ (nuclear saturation density) and $c_{\rm s}^2$ exceeds ${c^{2}}/{3}$ at 90\% credibility. The non-monotonic behavior suggests evidence of the state deviating from hadronic matter inside the very massive NSs. Assuming the new/exotic state is featured as it is softer than typical hadronic models or even with hyperons, we find that a sizable ($\geq 10^{-3}M_\odot$) exotic core, likely made of quark matter, is plausible for the NS with a gravitational mass above about $0.98M_{\rm TOV}$, where $M_{\rm TOV}$ represents the maximum gravitational mass of a non-rotating cold NS. The inferred $M_{\rm TOV} = 2.18^{+0.27}_{-0.13}M_\odot$ (90\% credibility) is well consistent with the value of $2.17^{+0.15}_{-0.12}M_\odot$ estimated independently with GW170817/GRB 170817A/AT2017gfo assuming a temporary supramassive NS remnant formed after the merger. PSR J0740+6620, the most massive NS detected so far, may host an exotic core with a probability of $\approx 0.36$.

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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