基于天体物理学先验的GW231123的衍射透镜解释
The diffraction-lensing interpretation of GW231123 with astrophysical priors
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中文总结 AI 辅助
研究GW231123，通过采用GWTC - 5总体分布为源参数先验，利用透镜光学深度量化透镜假设先验，探讨其是否被衍射透镜化，结果表明检测到此类透镜化事件不太可能，结论适用于孤立透镜。
中文摘要 AI 辅助
GW231123若未被透镜化，是一个罕见的双黑洞合并事件，其两个前身天体具有高质量和高自旋。我们表明，该信号能更好地由一个质量和自旋较低的合并事件拟合，该事件被一个红移质量约为1000M⊙的孤立物体衍射透镜化，该物体可建模为点质量或球对称致密晕。由于衍射透镜化事件也很罕见，假设检验应引用后验概率比而非贝叶斯因子，这需要量化我们对两个假设的先验信念。我们采用GWTC - 5总体分布作为源参数先验，并通过透镜光学深度量化透镜假设的先验。对于点质量透镜，宇宙中黑洞丰度的观测约束给出了光学深度的上限，进而给出后验概率的上限，这并不排除透镜化。然而，使用星团中形成的中等质量黑洞的预测质量函数会得到低光学深度，强烈不支持透镜化。对于暗物质晕透镜，标准的无碰撞冷暗物质不会形成足够致密的晕以给出所需的光学深度，但具有低速大截面的自相互作用暗物质可引发引力热坍缩并形成它们，在这种情况下后验概率尚无定论。无论哪种情况，从频率主义角度看，检测到具有GW231123性质的透镜化事件不太可能。这些结论适用于孤立透镜，而嵌入外部引力势中的透镜可能会改变情况。
英文摘要
GW231123, if unlensed, is a rare binary black hole merger with high masses and high spins for both progenitors. We show that the signal is better fitted by a lower-mass, lower-spin merger that is diffraction-lensed by an isolated object of redshifted mass $\sim 1000\,\rm M_\odot$, modeled either as a point mass or as a spherically symmetric compact halo. Because diffraction-lensed events are also rare, hypothesis testing should quote the posterior odds ratio rather than the Bayes factor, which requires quantifying our prior belief in the two hypotheses. We adopt the GWTC-5 population distribution as our source parameter prior, and quantify the prior on the lens hypothesis through the lensing optical depth. For a point-mass lens, observational constraints on the abundance of black holes in the Universe yield an upper bound on the optical depth, and hence on the posterior odds, which do not rule out lensing. However, using a predicted mass function of intermediate-mass black holes formed in star clusters gives a low optical depth that strongly disfavors lensing. For a dark matter halo lens, standard collisionless cold dark matter does not form halos compact enough to give the required optical depth, but self-interacting dark matter with a large cross section at low velocities can trigger gravothermal collapse and form them, in which case the posterior odds are inconclusive. In either case, from a frequentist perspective, we show that detecting a lensed event with properties like GW231123 is unlikely. These conclusions apply to isolated lenses, while a lens embedded in an external gravitational potential could change the picture.
