arXiv 1706.061112017-06astro-ph.COastro-ph.IMhep-ph

通过跨维推理探测强透镜系统中的小尺度结构

Probing the small-scale structure in strongly lensed systems via transdimensional inference

Tansu Daylan, Francis-Yan Cyr-Racine, Ana Diaz Rivero, Cora Dvorkin, Douglas P. Finkbeiner

发表信息：: 2018 ApJ 854 141
DOI：: 10.3847/1538-4357/aaaa1e

摘要：

强透镜效应是研究宇宙中小尺度密度涨落的一种灵敏的方法。我们实现了一种新的方法来建模强透镜系统使用概率编目，这是一个transdimensional，分层和贝叶斯框架，从元模型（具有不同维度的模型的联盟）与观察到的光子计数图一致的样本。概率编目使我们能够稳健地表征具有不同数量的subhalos的透镜模型内和透镜模型之间的建模协方差。与传统的海底晕编目不同，它不需要模型海底晕将拟合优度提高到检测阈值以上。相反，它允许利用光子计数图中包含的所有信息，例如，当约束次晕质量函数时。我们进一步表明，不包括这些小的subhalos在镜头模型中，固定尺寸的推理方法可以显着错误的数据模型。使用模拟的哈勃太空望远镜（HST）数据集，我们表明，subhalo质量函数可以探测，即使在样本目录中的许多subhalo单独低于检测阈值，将缺席在传统的目录。随着计划中的宽视场红外空间望远镜（WFIRST），在高分辨率，深强透镜图像中的暗晕的同时概率编目有可能限制在更低的质量下的晕质量函数。

英文摘要：

Strong lensing is a sensitive probe of the small-scale density fluctuations in the Universe. We implement a novel approach to modeling strongly lensed systems using probabilistic cataloging, which is a transdimensional, hierarchical, and Bayesian framework to sample from a metamodel (union of models with different dimensionality) consistent with observed photon count maps. Probabilistic cataloging allows us to robustly characterize modeling covariances within and across lens models with different numbers of subhalos. Unlike traditional cataloging of subhalos, it does not require model subhalos to improve the goodness of fit above the detection threshold. Instead, it allows the exploitation of all information contained in the photon count maps, for instance, when constraining the subhalo mass function. We further show that, by not including these small subhalos in the lens model, fixed-dimensional inference methods can significantly mismodel the data. Using a simulated Hubble Space Telescope (HST) dataset, we show that the subhalo mass function can be probed even when many subhalos in the sample catalogs are individually below the detection threshold and would be absent in a traditional catalog. With the planned Wide Field Infrared Space Telescope (WFIRST), simultaneous probabilistic cataloging of dark subhalos in high-resolution, deep strong lens images has the potential to constrain the subhalo mass function at even lower masses.

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