Discovering Poor Groups with Strong Lenses

ast -0206084安。“穷群”是星系的常见环境，在这些环境中，被认为驱动星系演化的机制（主要是星系-星系相互作用）比在更热、更密集的星系团中要少。因此，任何成功的星系演化模型至少必须在大范围的红移范围内再现穷星系群的星系特性。这项工作将利用引力透镜的特性作为探索星系演化的工具。它将构成对已知的56个强透镜场的星系的第一次全面的光谱观测，从那些即使是目前的、约束很差的透镜模型也需要在透镜红移处或附近有额外质量贡献的星系开始。仔细的建模表明，以这种方式确定的任何群体的质量、浓度和红移都代表了动态进化群体的更大群体。这项调查将极大地改进透镜分析，不仅通过在透镜环境和视线中表征星系，而且通过限制单个群的速度色散和质心以及不同红移的复合群的速度色散剖面。因此，哈勃常数和暗能量的新极限将与更经典的方法得出的结果相辅相成。＊＊＊

AST-0206084Zabludoff, Ann I."Poor groups" are common environments for galaxies in which the mechanisms thought to drive galaxy evolution (primarily galaxy-galaxy interactions) are fewer than in hotter, denser galaxy clusters. Therefore, any successful galaxy evolution model must, at the very least, reproduce the properties of galaxies in poor groups over a wide range of redshifts. This work will use the properties of gravitational lenses as a tool to explore galaxy evolution. It will constitute the first comprehensive spectroscopic observations of galaxies in the fields of the 56 known strong lenses, starting with those for which even the current, poorly-constrained lensing models require a contribution from additional mass at or near the lens redshift. Careful modeling suggests that the masses, concentrations, and redshifts of any groups identified in this manner are representative of the larger population of dynamically evolved groups. This survey will greatly improve lensing analyses not only by characterizing galaxies in the lens environment and along the line-of-sight, but also by constraining the velocity dispersion and centroid of individual groups and the velocity dispersion profiles of composite groups at different redshifts. As a result, new limits will be placed on the Hubble constant and dark energy that are complementary to those derived from more classical methods. ***