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arXiv 1809.09845astro-ph.CO
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用更新的星系尺度强引力透镜样品评价透镜质量模型在宇宙学应用中的作用

Assessing the effect of lens mass model in cosmological application with updated galaxy-scale strong gravitational lensing sample

Yun Chen, Ran Li, Yiping Shu, Xiaoyue Cao

摘要:

通过比较早型透镜星系的动力学质量和透镜质量,我们可以约束星系的宇宙学参数和密度分布。我们用161个星系尺度的强透镜系统研究了该方法对宇宙学参数的约束能力和透镜质量模型的影响,这是目前拥有高分辨率成像和恒星动力学数据的最大样本。我们假设透镜的幂律质量模型,并考虑$γ$的三种不同参数化(即,总质量密度曲线的斜率)以包括$γ$对红移和表面质量密度的依赖性的影响。当治疗$δ$(即,光度密度剖面的斜率)作为所有透镜星系的普适参数,我们发现宇宙学参数$Ω_m$的极限是相当弱的和有偏差的,并且在用三种不同形式参数化$γ$的方案中严重依赖于透镜质量模型。当把$δ$作为每个透镜的观测量时,只有在考虑了$γ$对红移和表面质量密度的依赖性的情况下,才能得到$Ω_m$的无偏估计,即在平坦的$Λ$ CDM模型框架下,在68\%置信水平下的$Ω_m = 0.381^{+0.185}_{-0.154}$。我们的结论是,显着的依赖性$γ$的红移和表面质量密度,以及固有的散射之间的透镜,$δ$,需要适当地考虑在这种方法。

英文摘要:

By comparing the dynamical and lensing masses of early-type lens galaxies, one can constrain both the cosmological parameters and the density profiles of galaxies. We explore the constraining power on cosmological parameters and the effect of the lens mass model in this method with 161 galaxy-scale strong lensing systems, which is currently the largest sample with both high resolution imaging and stellar dynamical data. We assume a power-law mass model for the lenses, and consider three different parameterizations for $γ$ (i.e., the slope of the total mass density profile) to include the effect of the dependence of $γ$ on redshift and surface mass density. When treating $δ$ (i.e., the slope of the luminosity density profile) as a universal parameter for all lens galaxies, we find the limits on the cosmological parameter $Ω_m$ are quite weak and biased, and also heavily dependent on the lens mass model in the scenarios of parameterizing $γ$ with three different forms. When treating $δ$ as an observable for each lens, the unbiased estimate of $Ω_m$ can be obtained only in the scenario of including the dependence of $γ$ on both the redshift and the surface mass density, that is $Ω_m = 0.381^{+0.185}_{-0.154}$ at 68\% confidence level in the framework of a flat $Λ$CDM model. We conclude that the significant dependencies of $γ$ on both the redshift and the surface mass density, as well as the intrinsic scatter of $δ$ among the lenses, need to be properly taken into account in this method.

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