We investigate the possibility that GW170817 was not the merger of two conventional neutron stars (NS), but involved at least one if not two hybrid stars with a quark matter core that might even belong to a third family of compact stars. To this end, we develop a Bayesian analysis method for selecting the most probable equation of state (EoS) under a set of constraints from compact star physics, which now also include the tidal deformability from GW170817 and the first result for the mass and radius determination for PSR J0030+0451 by the NICER Collaboration. We apply this method for the first time to a two-parameter family of hybrid EoS based on the DD2 model with nucleonic excluded volume for hadronic matter and the color superconducting generalized nlNJL model for quark matter. The model has a variable onset density for deconfinement and can mimic the effects of pasta phases with the possibility of producing a third family of hybrid stars in the mass-radius diagram. The main findings of this study are that: (1) the presence of multiple configurations for a given mass (twins or even triples) corresponds to a set of disconnected lines in the ${\Lambda }_1$ – ${\Lambda }_2$ diagram of tidal deformabilities for binary mergers, so that merger events from the same mass range may result in a probability landscape with different peak positions; (2) the Bayesian analysis with the above observational constraints favors an early onset of the deconfinement transition, at masses of $M_{\mathrm{onset}}\le 0.8M_{\odot }$ with an M–R relationship that in the range of observed neutron star masses is almost indistinguishable from that of a soft hadronic Akmal, Pandharipande, and Ravenhall (APR) EoS ; (3) a few, yet fictitious measurements of the NICER experiment two times more accurate than the present value and a different mass and radius that would change the posterior likelihood so that hybrid EoS with a phase transition onset in the range $M_{\mathrm{onset}}$ = 1.1–1.6 $M_{\odot }$ would be favored.

中文翻译：

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GW170817是规范中子星合并吗？具有第三恒星族的贝叶斯分析

我们研究了GW170817不是两个常规中子星（NS）合并，而是涉及至少一个（如果不是两个）具有夸克物质核的混合星的可能性，夸克物质核甚至可能属于第三类紧凑恒星。为此，我们开发了一种贝叶斯分析方法，用于根据紧凑型恒星物理学的一组约束条件选择最可能的状态方程（EoS），该方法现在还包括GW170817的潮汐变形能力以及质量和半径确定的第一个结果NICER协作提供的PSR J0030 + 0451。我们将这种方法首次应用于基于DD2模型的二参数杂化EoS系列，该模型具有强子物质的核排除体积和夸克物质的彩色超导广义nlNJL模型。该模型具有可变的起始约束密度，可以模拟面食相的影响，并有可能在质量半径图中生成第三类杂星。这项研究的主要发现是：（1）对于给定的质量（双胞胎甚至三胞胎），存在多个构型，对应于一组不连续的线。 ${\Lambda }_{\mathrm{1个}}$ – ${\Lambda }_2$ 二元合并的潮汐变形性图，因此来自相同质量范围的合并事件可能会导致具有不同峰值位置的概率图；（2）具有上述观察约束的贝叶斯分析有利于解除约束过渡的早发，其质量为 ${\mathrm{中号}}_{\mathrm{发作}}\le 0。8{\mathrm{中号}}_{\odot }$ 具有M – R关系，在观测到的中子星质量范围内，与软强子阿克马尔，潘达里潘德和拉文豪尔（APR）EoS几乎没有区别；（3）NICER实验的一些虚构测量值是当前值的两倍，并且质量和半径不同，这将改变后验概率，从而使相变开始在该范围内的混合EoS ${\mathrm{中号}}_{\mathrm{发作}}$ = 1.1–1.6 ${\mathrm{中号}}_{\odot }$ 将受到青睐。