论文标题
引力透镜SDSSJ0946+1006中的深色子结构的意外高浓度
An unexpected high concentration for the dark substructure in the gravitational lens SDSSJ0946+1006
论文作者
论文摘要
先前在重力透镜Galaxy SDSSJ0946+1006中通过其镜头图像的扰动中检测到了不可见的子结构。使用柔性模型作为主光晕和subhalo扰动来适合镜头图像，我们证明了Subhalo具有极高的中央密度和陡峭的密度斜率。 subhalo的推断浓度远高于$λ$ CDM的相似质量的浓度的预期散射。 We robustly infer the subhalo's projected mass within 1 kpc to be $\sim 2$-$3.7\times 10^9$M$_\odot$ at $>$95% CL for all our lens models, while the average slope of the subhalo's projected density profile over the radial range 0.75-1.25 kpc is constrained to be steeper than isothermal ($γ_{2D} \ Lessim -1 $）。通过直接对subhalo灯进行建模，我们推断出其光度的保守上限$ l_v <1.2 \ times 10^8l_ \ odot $在95％Cl中，这表明Perturber是暗物质的主导。为了与$λ$ CDM的期望相比，我们分析了Subhalos在Illustris TNG100-1中的镜头星系中的类似物中进行了许多视线模拟，并找到了数百个Subhalos，这些Subhalos在$ \ gtrsim 2 \ gtrsim 2 \ times10^9m_ \ odot $中获得了预计的质量。但是，只有不到1％的模拟观察结果产生了足够陡峭的对数斜坡，以至于与我们的镜头模型保持一致，并且它们的所有$ $都具有超过观测值允许的恒星质量。我们得出的结论是，在$λ$ CDM宇宙中，如此黑暗，高度浓缩的Subhalo的存在是出乎意料的。最后，我们表明，如果假定Perturber是视线结构，而不是Subhalo，则与CDM的张力不会显着降低。
The presence of an invisible substructure has previously been detected in the gravitational lens galaxy SDSSJ0946+1006 through its perturbation of the lensed images. Using flexible models for the main halo and the subhalo perturbation to fit the lensed images, we demonstrate that the subhalo has an extraordinarily high central density and steep density slope. The inferred concentration for the subhalo is well above the expected scatter in concentrations for $Λ$CDM halos of similar mass. We robustly infer the subhalo's projected mass within 1 kpc to be $\sim 2$-$3.7\times 10^9$M$_\odot$ at $>$95% CL for all our lens models, while the average slope of the subhalo's projected density profile over the radial range 0.75-1.25 kpc is constrained to be steeper than isothermal ($γ_{2D} \lesssim -1$). By modeling the subhalo light directly, we infer a conservative upper bound on its luminosity $L_V < 1.2\times 10^8L_\odot$ at 95% CL, which shows that the perturber is dark matter dominated. To compare to $Λ$CDM expectations, we analyze subhalos within analogues of lensing galaxies in the Illustris TNG100-1 simulation over many lines of sight, and find hundreds of subhalos that achieve a projected mass within 1 kpc of $\gtrsim 2\times10^9M_\odot$. However, less than 1% of the mock observations yield a log-slope steep enough to be consistent with our lensing models, and they $all$ have stellar masses in excess of that allowed by observations by about an order of magnitude or more. We conclude that the presence of such a dark, highly concentrated subhalo is unexpected in a $Λ$CDM universe. Finally, we show that this tension with CDM is not significantly reduced if the perturber is assumed to be a line-of-sight structure, rather than a subhalo.
