Galaxy-galaxy strong lens perturbations: line-of-sight haloes versus lens subhaloes
Galaxy-galaxy strong lens perturbations: line-of-sight haloes versus lens subhaloes
复制标题
星系-星系强透镜扰动：视线晕与透镜亚晕
DOI：
10.1093/mnras/stac759
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发表时间：
2022
影响因子：
4.8
通讯作者：
He Q
中科院分区：
文献类型：
--
作者：
He Q
我们重新推导了在星系-星系强透镜观测中相对于透镜亚晕的干涉视距晕的数量密度，这些干扰可以产生可检测的图像波动。先前的研究通过比较小质量暗晕所引起的透镜偏转角度和透镜内亚晕所引起的偏转角度，计算出了视距内小质量暗晕的探测极限。然而，这过于简化了亚晕和视距晕在观测结果上的差异。此外，它没有考虑额外的亚晕和主透镜的不确定性质之间的简并。为了更符合对真实世界观测的分析，我们认为视距光晕只有在将其添加到平滑模型中才能在重建图像中产生统计上显着的改善。我们发现，可检测的视线扰动的数量密度已被高估了多达两个因素在以前的文献。对于典型的透镜几何形状和配置，极深成像对亚晕的视线干扰是亚晕的两倍，但中等深度成像对亚晕的视线干扰只比亚晕稍微多一点。
We rederive the number density of intervening line-of-sight haloes relative to lens subhaloes in galaxy-galaxy strong lensing observations, where these perturbers can generate detectable image fluctuations. Previous studies have calculated the detection limit of a line-of-sight small-mass dark halo by comparing the lensing deflection angles it would cause, to those caused by a subhalo within the lens. However, this overly simplifies the difference in observational consequences between a subhalo and a line-of-sight halo. Furthermore, it does not take into account degeneracies between an extra subhalo and the uncertain properties of the main lens. More in keeping with analyses of real-world observations, we regard a line-of-sight halo as detectable only if adding it to a smooth model generates a statistically significant improvement in the reconstructed image. We find that the number density of detectable line-of-sight perturbers has been overestimated by as much as a factor of two in the previous literature. For typical lensing geometries and configurations, very deep imaging is sensitive to twice as many line-of-sight perturbers as subhaloes, but moderate depth imaging is sensitive to only slightly more line-of-sight perturbers than subhaloes.