Gravitational flexion, its measurement and its application to galaxy clusters

引力弯曲、测量及其在星系团中的应用

• 批准号: 179826617
• 负责人: Professor Dr. Matthias Bartelmann
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/179826617?language=en
• 关键词: Gravitational; flexion; its; measurement; application

Gravitational lensing by cosmic structures is one of the preferred methods for mapping the spatial distribution and the total amount of dark matter. For this purpose, the gravitational tidal field is routinely being used, the so-called gravitational shear, which can be measured from the elliptical distortions of the images of distant galaxies in the background of the gravitationally lensing objects. The angular resolution of such measurements is limited to angular scales of approximately half an arc minute. It would be desirable, however, to probe the distribution of dark matter also on smaller scales in order to test the hypothesis of cold dark matter.Access to such measurements is promised by the derivatives of the tidal field which can be combined to form quantities of single or three-fold rotational symmetry. They are called the F and G flexions, both of which have two components.The present application is meant to extend and conclude a previously granted project aiming at measuring for the first time both components of the flexions in a reliable and unbiased way. The work programme originally foreseen was delayed by considerable difficulties, which were uncovered and solved in the course of the work.We are now in a position to measure the flexions of realistically simulated galaxy images. During the further (fourth) year of the project, for which we apply for funding here, the measurement method developed so far will be extended to observational data and used for calibrating the statistical distribution of intrinsic flexions in galaxy images. Finally, the flexion will be used for the first time jointly with the shear to reconstruct the matter distribution of at least one galaxy cluster.

宇宙结构引力透镜是绘制暗物质空间分布和总量的首选方法之一。为此，通常使用重力潮汐场，即所谓的引力切变，它可以通过引力透镜物体背景中遥远星系的图像的椭圆形扭曲来测量。这种测量的角度分辨率被限制在大约半角分的角度刻度。然而，为了检验冷暗物质的假说，最好也在更小的尺度上探测暗物质的分布。这样的测量是由潮汐场导数来保证的，潮汐场导数可以组合起来形成单重或三重旋转对称量。它们被称为F和G屈曲，它们都有两个分量。本申请意在扩展和结束先前批准的一个项目，该项目旨在以可靠和无偏的方式首次测量屈曲的两个分量。最初预计的工作计划由于相当大的困难而被推迟，这些困难在工作过程中被发现和解决了。我们现在能够测量真实模拟的星系图像的弯曲。在该项目的下一个(第四)年，我们在这里申请资金，到目前为止开发的测量方法将扩展到观测数据，并用于校准星系图像中固有挠曲的统计分布。最后，挠曲将首次与切变一起用于重建至少一个星系团的物质分布。