Investigations in Galaxy Intrinsic Alignment 3-Point Correlations (GGI, GII, III)

弱引力透镜效应——由于干涉质量导致光线弯曲而导致的背景星系图像的细微扭曲——是暗能量最有潜力的强大探测之一。但是，透镜信号的测量和解释由于星系图像排列之间的内在相关性而变得复杂。当物理上接近的星系被周围物质的引力场排列时，或者当物质结构将靠近它的星系的方向与远处星系的透镜图像联系起来时，内在相关性就会产生。先前的研究表明，如果忽略本征排列，暗能量状态方程的透镜约束将产生高达50%的偏差。该项目将研究对准的三点内在相关性，以及如何从透镜信号中去除它们的影响。该项目的首席研究员、合作者和研究生将进行分析计算和数值积分，以开发“自校准”方法，该方法使用可以从同一透镜调查中提取的额外相关性来计算固有对准污染并消除它。他们将得出3点相关性的统计估计，并研究它们对红移、光度、颜色和形态的依赖关系，以了解它们的缩放特性。这项工作将对宇宙学产生广泛的影响，对透镜调查进行必要的修正。它还将为研究生教育和首席研究员所在机构的发展研究项目做出贡献。首席研究员还将参与与当地业余天文团体的联系，并参与公开演讲和教师专业发展计划。

Weak gravitational lensing - the subtle distortion of the images of background galaxies caused by the bending of light by intervening mass - is one of the most potentially powerful probes of dark energy. But measurement and interpretation of the lensing signal is complicated by intrinsic correlations between the alignments of galaxy images. Intrinsic correlations can arise when physically close galaxies are aligned by the gravitational field of the matter surrounding them, or when a matter structure links the orientation of a galaxy close to it to the lensed image of a galaxy far behind. Previous studies have shown that if intrinsic alignments are ignored, the lensing constraints on the dark energy equation of state are biased by up to 50%. This project will study the 3-point intrinsic correlations of alignments and how their effects can be removed from the lensing signal. The Principal Investigator, collaborator, and graduate student supported by the project will carry out analytical calculations and numerical integrations to develop the method of "self-calibration," which uses additional correlations that can all be extracted from the same lensing survey to calculate the intrinsic alignment contamination and remove it. They will derive statistical estimators of the 3-point correlations and study their dependencies on redshift, luminosity, color, and morphology in order to understand their scaling properties. The work will have broad impact in cosmology, in developing an essential correction to lensing surveys. It will also contribute to graduate education and to the development research program at the Principal Investigator's institution. The Principal Investigator will also be involved in outreach to local amateur astronomy groups and through participation in public presentations and professional development programs for teachers.