报告题目：MApping the Most Massive Overdensity Through Hydrogen (MAMMOTH)

　　报 告 人：Dr Zheng Cai （University of Arizona）

　　摘    要：We have undertaken a survey of the most massive galaxy structures in the early universe at z=2-4, traced by regions of the highest optical depth from IGM Lyα absorption over large scale of 10-30 Mpc. Our cosmological simulations show a strong correlation between the optical depth of intergalactic Ly-alpha absorption and mass overdensities at scales of 10- 40 Mpc. Based on our simulations and MMT observations, we have developed technique to search for the largest IGM Lyα absorption systems. By examining the absorption spectra of ～60,000 quasar sight-lines in the SDSS-III at z = 2.32 ± 0.04 we have identified the first field that traced by group of IGM Lyα absorbers, which then can be probed in Ly-alpha emission with our custom narrowband filter. The overdense nature of this field is further suggested by a high concentration of quasars at the same redshift. Our KPNO-4m/MOSAIC narrowband imaging and follow-up LBT/MODS spectroscopy have successfully revealed the large-scale galaxy overdensities in this field. Both our simulation and early observational results suggest the largest IGM Ly-alpha absorption systems could be used as a powerful way of tracing most massive galaxy structures in the early universe. In this talk, I will also highlight the great potential of using future ambitious survey like SDSS-IV, DESI, etc., to conduct the studies of the IGM and most massive large-scale structures.

　　时    间：2015年04月29日（星期三）14:00

　　地    点：（北京西路2号）紫台大楼619教室

　　联 系 人：赵奥（83332112）

欢迎大家积极参加！

　　                                        紫金山天文台学术委员会