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arXiv 1601.01671astro-ph.COastro-ph.GA
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SHARP - II。强透镜中的质量结构不一定是暗物质子结构:来自边缘盘的通量比异常

SHARP - II. Mass structure in strong lenses is not necessarily dark matter substructure: A flux ratio anomaly from an edge-on disc

J. - W. Hsueh, C. D. Fassnacht, S. Vegetti, J. P. McKean, C. Spingola, M. W. Auger, L. V. E. Koopmans, D. J. Lagattuta

摘要:

引力透镜通量比异常为测量遥远星系中的暗物质亚结构提供了一种强有力的技术。然而,在使用这些通量比异常来测试星系形成模型之前,必须确定给定的异常确实是由于暗物质子结构的存在,而不是由于透镜星系晕的其他成分或传播效应。在这里,我们提出的情况下,CLASS~B1555+375,它有一个很强的无线电波长通量比异常。我们的高分辨率近红外凯克~II自适应光学成像和档案哈勃太空望远镜的数据显示,在这个系统中的透镜星系有一个明确的边缘盘组件,直接跨越对图像,表现出通量比异常。我们发现,简单的模型,包括光盘可以重现厘米波长通量比异常,而不需要额外的暗物质子结构。虽然还需要进一步的研究,我们的研究结果表明,假设所有的通量比异常是由于人口的暗物质子晕可能是不正确的,分析,不占透镜宏观模型的全部复杂性可能高估的子结构质量分数在大规模透镜星系。

英文摘要:

Gravitational lens flux-ratio anomalies provide a powerful technique for measuring dark matter substructure in distant galaxies. However, before using these flux-ratio anomalies to test galaxy formation models, it is imperative to ascertain that the given anomalies are indeed due to the presence of dark matter substructure and not due to some other component of the lensing galaxy halo or to propagation effects. Here we present the case of CLASS~B1555+375, which has a strong radio-wavelength flux-ratio anomaly. Our high-resolution near-infrared Keck~II adaptive optics imaging and archival Hubble Space Telescope data reveal the lensing galaxy in this system to have a clear edge-on disc component that crosses directly over the pair of images that exhibit the flux-ratio anomaly. We find that simple models that include the disc can reproduce the cm-wavelength flux-ratio anomaly without requiring additional dark matter substructure. Although further studies are required, our results suggest the assumption that all flux-ratio anomalies are due to a population of dark matter sub-haloes may be incorrect, and analyses that do not account for the full complexity of the lens macro-model may overestimate the substructure mass fraction in massive lensing galaxies.

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