Flux-ratio anomalies from discs and other baryonic structures in the Illustris simulation
Flux-ratio anomalies from discs and other baryonic structures in the Illustris simulation
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DOI：
10.1093/mnras/stx3320
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发表时间：
2017-07
影响因子：
4.8
通讯作者：
J. Hsueh;G. Despali;S. Vegetti;Dandan Xu;C. Fassnacht;R. C. D. Physics;U. California;Davis;
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文献类型：
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作者：
J. Hsueh;G. Despali;S. Vegetti;Dandan Xu;C. Fassnacht;R. C. D. Physics;U. California;Davis;
引力透镜类星体多幅图像中的通量比如果与透镜星系质量分布的平滑模型所预测的通量比不同，则可以提供透镜星系晕中暗物质亚结构的证据。然而，透镜星系中的重子结构，如边缘盘，也可能产生通量比异常。在这项工作中，我们首次从数值模拟的角度对重子引起的通量比反常进行了统计分析。我们在Illustris模拟中选择了不同形态类型的星系，并通过模拟的晕进行射线跟踪，其中包括主透镜星系中的重子，但不包括任何子结构，以探索纯重子效应。我们的光线追踪结果表明，重子分量可能是透镜类星体通量比反常的主要原因，而边缘盘透镜引起的反常最强。我们发现，重子分量使早期透镜中发现高通量比反常的几率增加了约8%，而在盘状透镜中发现高通量比异常的几率增加了约10%-20%。重子效应还会导致13%的模拟透镜出现天文测量异常。我们的结果表明，当考虑重子的影响时，透镜星系的形态在通量比反常的分析中变得很重要，而重子的存在也可以部分解释观测到的(高)反常频率与CDM模拟预测的由于亚晕的存在而产生的差异。
The flux ratios in the multiple images of gravitationally lensed quasars can provide evidence for dark matter substructure in the halo of the lensing galaxy if the flux ratios differ from those predicted by a smooth model of the lensing galaxy mass distribution. However, it is also possible that baryonic structures in the lensing galaxy, such as edge-on discs, can produce flux-ratio anomalies. In this work, we present the first statistical analysis of flux-ratio anomalies due to baryons from a numerical simulation perspective. We select galaxies with various morphological types in the Illustris simulation and ray-trace through the simulated halos, which include baryons in the main lensing galaxies but exclude any substructures, in order to explore the pure baryonic effects. Our ray-tracing results show that the baryonic components can be a major contribution to the flux-ratio anomalies in lensed quasars and that edge-on disc lenses induce the strongest anomalies. We find that the baryonic components increase the probability of finding high flux-ratio anomalies in the early-type lenses by about 8% and by about 10 - 20% in the disc lenses. The baryonic effects also induce astrometric anomalies in 13% of the mock lenses. Our results indicate that the morphology of the lens galaxy becomes important in the analysis of flux-ratio anomalies when considering the effect of baryons, and that the presence of baryons may also partially explain the discrepancy between the observed (high) anomaly frequency and what is expected due to the presence of subhalos as predicted by the CDM simulations.