普查研究宇宙恒星形成活动最剧烈的z～2-3时期不同环境中星系的各方面性质，是理解大质量星系如何形成、环境对星系早期形成影响的关键。本申请项目计划搜寻证认2个z=2.25处极端大质量的高密度区域BOSS1244和BOSS1542，利用多个观测计划获得的数据，研究其成员星系的性质。计划开展的研究内容有：1）利用Hα和Lyα发射线星系示踪这两个高密度区域的结构、形态和成团性，探究大质量原初星系团演化增长模式；2）测定其中的Hα光度函数，给出z～2-3时期致密环境中星系恒星形成率函数；3）基于MMT近红外光谱观测，测定给出中心区域大质量星系的消光、电离参数、AGN活动、化学丰度和运动学特征；4）测定中心区域的动力学结构和性质，检验是否已经位力化；5）研究原初星系团内IGM吸收云、星系、类星体的演化关联。

Studying the properties of galaxies in different environment at z～2-3, the peak of cosmic star formation density, is essential to understanding how massive galaxies formed and how environment effected on galaxy formation. This program aims to identify two extremely massive overdensities BOSS124 and BOSS1542 at z=2.25, and investigate the properties of their member galaxies using a set of observed data. The content of this research program includes: 1) map the structures and morphologies of the two massive overdensities using Hα and Lyα emitters and shed insights into the growth of proto-clusters of galaxies; 2) determine Hαluminosity function, and present star formation rate function of overdensities at z～2-3; 3) measure extinction, ionization, AGN activity, metallicity and kinematics from near-infrared spectroscopic data obtained with MMT; 4) explore the dynamics of the central regions of the two proto-cluster of galaxies and the evolutionary stage of relaxing; 5) address connections between Lyα absorption systems, galaxies, quasars within the extremely oversense structures at z=2.25.