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arXiv 2104.07783astro-ph.HEastro-ph.SR
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Poking Holes:寻找LIGO/Virgo黑洞人口的差距

Poking Holes: Looking for Gaps in LIGO/Virgo's Black Hole Population

Bruce Edelman, Zoheyr Doctor, Ben Farr

摘要:

恒星演化模型预测,由于对不稳定超新星(PISNe),$\sim55 M_\odot - 120 M_\odot$的黑洞质谱中存在一个间隙。通过对黑洞质量的天体物理分布进行分层模拟,我们研究了第二个引力波瞬变星表(GWTC-2)中可能存在的这种“上层”质量隙。我们扩展截断和Powerlaw+峰值质量分布的家庭,让一个明确的差距的质量分布,并适用于GWTC-2的扩展模型。我们发现,与截断模型有轻微的证据有利于上质量差距与对数贝叶斯因子$\ln \mathcal{B} = 2.79$,推断的下限和上限分别在$56.12_{-4.38}^{+7.54} M_\odot$,和$103.74_{-6.32}^{+17.01} M_\odot$。当使用Powerlaw+Peak模型时,我们没有发现对间隙的偏好。当对以预期PISN间隙边界为中心的间隙边界施加更严格的先验时,有利于间隙的对数贝叶斯因子略微增加。然而,这些结果取决于最大质量的双星GW 190521的参数推断,后续分析表明,该来源可能是一个中间质量比合并,其组件质量跨越差距。使用Nitz & Capano(2021)分析的GW 190521后验样本,我们发现贝叶斯因子的增加有利于差距。然而,总体结论是不变的:当使用Powerlaw+Peak模型时,不存在对间隙的偏好。这项工作为约束对不稳定性和脉动对不稳定性超新星和高质量黑洞形成的物理学铺平了道路。

英文摘要:

Stellar evolution models predict the existence of a gap in the black hole mass spectrum from $\sim55 M_\odot - 120 M_\odot$ due to pair-instability supernovae (PISNe). We investigate the possible existence of such an "upper" mass gap in the second gravitational wave transient catalog (GWTC-2) by hierarchically modeling the astrophysical distribution of black hole masses. We extend the Truncated and Powerlaw+Peak mass distribution families to allow for an explicit gap in the mass distribution, and apply the extended models to GWTC-2. We find that with the Truncated model there is mild evidence favoring an upper mass gap with log Bayes Factor $\ln \mathcal{B} = 2.79$, inferring the lower and upper bounds at $56.12_{-4.38}^{+7.54} M_\odot$, and $103.74_{-6.32}^{+17.01} M_\odot$ respectively. When using the Powerlaw+Peak model, we find no preference for the gap. When imposing tighter priors on the gap bounds centered on the expected PISN gap bounds, the log Bayes factors in favor of a gap mildly increase. These results are however contingent on the parameter inference for the most massive binary, GW190521, for which follow up analyses showed the source may be an intermediate mass ratio merger that has component masses straddling the gap. Using the GW190521 posterior samples from the analysis in Nitz & Capano (2021), we find an increase in Bayes factors in favor of the gap. However, the overall conclusions are unchanged: There is no preference for a gap when using the Powerlaw+Peak model. This work paves the way for constraining the physics of pair-instability and pulsational pair-instability supernovae and high-mass black hole formation.

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