通过三重源平面透镜进行引力成像：重新审视 SDSSJ0946+1006 中挑战 $Λ$CDM 的暗子晕
Gravitational imaging through a triple source plane lens: revisiting the $Λ$CDM-defying dark subhalo in SDSSJ0946+1006
AI总结：
本文结合 HST 与 VLT-MUSE 多波段数据重新建模三重源平面透镜 SDSSJ0946+1006，证实其中存在约 $5.9σ$ 的暗扰动体，并发现其集中度更符合 CDM 预言，但探测显著性受源正则化影响。
摘要：
$Λ$CDM 范式成功解释了宇宙的大尺度结构，但在亚星系尺度上受到的约束仍较薄弱。引力透镜建模已被用于测量暗子结构在被透镜弧线上留下的印记，以检验 $Λ$CDM 的小尺度预言。然而，开展这些检验所需的方法受到透镜质量模型与源光轮廓之间简并性的影响。我们对独特的复合引力透镜 SDSSJ0946+1006 进行了案例研究；在该系统中已探测到一个暗的大质量子结构，而此前报告的高集中度在 $Λ$CDM 宇宙中似乎不太可能出现。我们首次同时利用 I 波段和 U 波段 HST 成像对前两个背景源进行建模，并使用 VLT-MUSE 发射线数据对最遥远的源进行建模。我们以 $5.9σ$ 置信水平恢复出一个透镜扰动体，其质量为 $\log_{10}(M_\mathrm{sub}/M_{\odot})=9.2^{+0.4}_{-0.1}$，集中度为 $\log_{10}c=2.4^{+0.5}_{-0.3}$。与此前报告相比，该集中度与 CDM 子晕更为一致；其质量也与矮卫星星系相当，而在扰动体所在位置，数据无法探测到这类星系的流量。一个质量为 $\log_{10}(M_\mathrm{BH}/M_{\odot})=8.9^{+0.2}_{-0.1}$ 的游荡黑洞则是可行的替代模型。我们系统研究了关于质量分布复杂性和源重建的不同假设；在所有情况下，子晕均以约 $\geq5σ$ 的水平被探测到。然而，源正则化方案的不同选择可能显著改变探测显著性，最高可达 $11.3σ$。
英文摘要：
The $Λ$CDM paradigm successfully explains the large-scale structure of the Universe, but is less well constrained on sub-galactic scales. Gravitational lens modelling has been used to measure the imprints of dark substructures on lensed arcs, testing the small-scale predictions of $Λ$CDM. However, the methods required for these tests are subject to degeneracies among the lens mass model and the source light profile. We present a case study of the unique compound gravitational lens SDSSJ0946+1006, wherein a dark, massive substructure has been detected, whose reported high concentration would be unlikely in a $Λ$CDM universe. For the first time, we model the first two background sources in both I- and U-band HST imaging, as well as VLT-MUSE emission line data for the most distant source. We recover a lensing perturber at a $5.9σ$ confidence level with mass $\log_{10}(M_\mathrm{sub}/M_{\odot})=9.2^{+0.4}_{-0.1}$ and concentration $\log_{10}c=2.4^{+0.5}_{-0.3}$. The concentration is more consistent with CDM subhalos than previously reported, and the mass is compatible with that of a dwarf satellite galaxy whose flux is undetectable in the data at the location of the perturber. A wandering black hole with mass $\log_{10}(M_\mathrm{BH}/M_{\odot})=8.9^{+0.2}_{-0.1}$ is a viable alternative model. We systematically investigate alternative assumptions about the complexity of the mass distribution and source reconstruction; in all cases the subhalo is detected at around the $\geq5σ$ level. However, the detection significance can be altered substantially (up to $11.3σ$) by alternative choices for the source regularisation scheme.
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