状态方程不确定性下电子俘获超新星产生的中子星质量
Neutron star masses from electron-capture supernovae under equation-of-state uncertainties
AI总结：
该研究分析了状态方程不确定性对电子俘获超新星产生的低质量中子星质量的影响，明确了其质量范围，指出最轻中子星或来自其他非标准形成通道。
AI中文摘要：
电子俘获超新星（ECSNe）是低质量中子星的一种有前景的形成通道，但其产生的中子星的最小引力质量既取决于前身星核心结构，也取决于中子星物质的状态方程（EOS）。我们计算了具有代表性成分的冷白矮星状氧-氖-镁（O--Ne--Mg）核心的电子俘获（EC）阈值引力质量（$M^\text{⋆}_\text{WD}$），并将重子数映射到由贝叶斯统一壳层-核心EOS集合构建的冷中子星构型上。尽管EC阈值密度对O--Ne--Mg混合物的浓度敏感，但O--Ne--Mg核心的阈值重子数仅微弱变化，产生狭窄的残余质量窗口。在从EC阈值质量O--Ne--Mg核心到残余中子星的转变过程中无重子质量损失的基准情形下，标准ECSNe产生的残余中子星引力质量为$1.24$--$1.265\\, M_\odot$，仅存在由EOS导致的微小分散。$0.01$--$0.02\\, M_\odot$的小重子质量损失会使该范围适度下移，但PSR J0453+1559的$1.174\\, M_\odot$伴星需要接近$0.10\\, M_\odot$的极端质量损失，这与当前ECSN模拟结果不符。我们发现，残余质量的EOS残余依赖性主要由核饱和密度附近的压强控制，而对应的潮汐形变仍对残余星的半径和致密性敏感。因此，低质量双中子星系统原则上可将ECSN类形成通道与EOS的引力波约束联系起来。我们的结果表明，ECSNe自然形成低质量中子星，但在受限质量范围内；观测到的最轻中子星可能需要低质量铁核坍缩、超剥离超新星或其他非标准通道。
英文摘要：
Electron-capture supernovae (ECSNe) are a promising formation channel for low-mass neutron stars, but the minimum gravitational mass of the neutron stars they produce depends on both the progenitor core structure and the neutron-star matter equation of state (EOS). We compute the electron-capture (EC) threshold gravitational mass ($M^\star_{WD}$) of cold white-dwarf-like O--Ne--Mg cores with representative compositions and map the baryon number onto cold neutron-star configurations constructed from a Bayesian ensemble of unified crust--core EOSs. Although the EC threshold density is sensitive to the concentrations of the O--Ne--Mg mixture, the threshold baryon number of the O--Ne--Mg core varies only weakly, producing a narrow remnant-mass window. In the baseline case with no baryonic mass loss during the transition from the EC threshold mass O--Ne--Mg core to the remnant neutron star, standard ECSNe yield remnant neutron stars with gravitational masses of $1.24$--$1.265\, M_\odot$, with only a small EOS-induced spread. Small baryonic mass losses of $0.01$--$0.02\, M_\odot$ shift this range modestly downward, but the $1.174\, M_\odot$ companion of PSR J0453+1559 would require an extreme mass loss close to $0.10\, M_\odot$, which is not favored by current ECSN simulations. We find that the residual EOS dependence of the remnant mass is controlled mainly by the pressure around nuclear saturation density, while the corresponding tidal deformability remains sensitive to the remnant radius and compactness. Thus, low-mass double neutron star systems can in principle connect ECSN-like formation channels with gravitational-wave constraints on the EOS. Our results show that ECSNe naturally form low-mass neutron stars, but within a restricted mass range; the lightest observed neutron stars likely require low-mass iron-core collapse, ultra-stripped supernovae, or other nonstandard channels.
