The matter environment of GAMA galaxy pairs studied with galaxy-galaxy-galaxylensing and KiDS data

利用星系-星系-星系透镜和 KiDS 数据研究 GAMA 星系对的物质环境

• 批准号: 435069740
• 负责人: Professor Dr. Peter Schneider
• 金额: --
• 依托单位: Argelander-Institut für Astronomie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/435069740?language=en
• 关键词: matter; environment; GAMA; galaxy; pairs

Galaxies of different types are found inside the high-density regions, or halos, of dark matter. The observed composition of galaxy types is not fully understood in detail but very likely depends on the local conditions in the matter density field. This explains the strong correlation between the number density of galaxies and the matter density which can be studied with the well-established effect of gravitational lensing: tidal distortions caused by density inhomogeneities shear the images of background galaxies and thus probe the matter field. Correlations between the observed shapes of background galaxies and positions of foreground galaxies therefore encode statistical information on galaxy physics, more interestingly so if we consider the correlation signal for different galaxy types.As application of such a correlation analysis, we propose to measure the mean gravitational shear from galaxy images in the Kilo-Degree Survey (KiDS) around galaxy pairs in the Galaxy-and-Mass Assembly (GAMA) survey. This three-point statistic, dubbed galaxy-galaxy-galaxy lensing (G3L), quantifies the mean projected matter density around galaxy pairs in excess of that for uncorrelated galaxies; the pairs can either be of the same type (unmixed pairs) or different type (mixed pairs). In contrast to traditional galaxy-galaxy lensing, which focuses on the mean shear around single galaxies, G3L is also sensitive to the correlation of positions of galaxies inside the same halo or the correlation of the type-dependent numbers of galaxies that occupy the halo. In addition, G3L is principally sensitive to the statistical alignment of galaxy pairs with respect to the halo matter distribution, whereas two-point statistics are only sensitive to the radial density profiles of stacked halos. Thus, a significantly measured G3L signal and its interpretation will refine our current understanding of the galaxy halo occupation.The details and applicability of this new tool for galaxy research still have to be established as we will do in this project. A special focus will be given to G3L of mixed pairs. To this end, we have already done a few steps in direction of a new theoretical model for the mixed-pair G3L. We also have demonstrated the feasibility of G3L measurements with certain unmixed pairs in GAMA and KiDS. To now move beyond this early project phase, we ask for DFG funding to investigate and improve the available G3L estimator by utilising the precise GAMA galaxy redshifts, to mature our (unpublished) G3L model for mixed galaxy pairs, and to perform systematic G3L measurements for unmixed and, for the first time, mixed GAMA galaxy pairs. These measurements will then be used to test G3L predictions of existing galaxy models and to refine the halo occupation statistics of galaxies. All in all, this project is a great opportunity for a couple of doctoral theses to work on exciting science in cosmology and galaxy physics with readily availablestate-of-the-art data.

在暗物质的高密度区域或晕圈内发现了不同类型的星系。观测到的星系类型的组成并没有完全了解细节，但很可能取决于物质密度场的局部条件。这解释了星系数量密度和物质密度之间的强相关性，可以用公认的引力透镜效应来研究：密度不均匀性引起的潮汐扭曲会剪切背景星系的图像，从而探测物质场。因此，观察到的背景星系形状和前景星系位置之间的相关性编码了星系物理学的统计信息，更有趣的是，如果我们考虑不同星系类型的相关性信号，那么就更有趣了。作为这种相关性分析的应用，我们建议从星系与质量大会（GAMA）中星系对周围的千度巡天（KiDS）星系图像中测量平均引力切变调查.这种三点统计量被称为星系-星系-星系透镜（G3 L），它量化了星系对周围的平均投影物质密度超过不相关星系的平均投影物质密度;这些对可以是同一类型（非混合对）或不同类型（混合对）。与传统的星系-星系透镜效应主要关注单个星系周围的平均切变相反，G3 L对同一晕内星系位置的相关性或占据晕的星系类型相关数量的相关性也很敏感。此外，G3 L主要是敏感的统计排列的星系对相对于晕物质分布，而两点统计只敏感的径向密度分布的堆叠晕。因此，显着测量的G3 L信号及其解释将完善我们目前对星系晕占据的理解。这个用于星系研究的新工具的细节和适用性仍有待确定，就像我们在本项目中所做的那样。一个特别的重点将给予G3 L的混合对。为此，我们已经在混合对G3 L的新理论模型的方向上做了一些步骤。我们还证明了在GAMA和KiDS中使用某些未混合对进行G3 L测量的可行性。现在超越这个早期的项目阶段，我们要求DFG资助，通过利用精确的GAMA星系红移来调查和改进可用的G3 L估计器，以成熟我们的（未发表的）混合星系对的G3 L模型，并首次对未混合和混合GAMA星系对进行系统的G3 L测量。这些测量将用于测试现有星系模型的G3 L预测，并改进星系的晕占据统计。总而言之，这个项目是一个很好的机会，为一对夫妇的博士论文工作，在宇宙学和星系物理学激动人心的科学与现成的最先进的数据。