|Speaker:||Kazuaki Ota (RIKEN)|
|Title:||Deep Surveys of z=7 Ly-alpha Emitting Galaxies with Subaru Telescope:Implications for Galaxy Evolution and Reionization|
|Date:||Wed, Aug 05, 2009, 11:00 - 12:00|
|Place:||Seminar Room at IPMU Prefab. B|
We conducted a deep narrowband NB973 filter (FWHM=200A centered at 9755A) survey of z=7 Ly-alpha emitting galaxies (LAEs) in the Subaru/XMM-Newton Deep Field, using the fully depleted CCDs newly installed on the Subaru Telescope Suprime-Cam, which has the highest sensitivity at ~1um. Reaching the depth ~0.5 mag deeper than the previous survey that discovered a z=6.96 LAE, we detected at least two probable z=7 LAE candidates in addition to a few less robust but possible candidates. Even if we assume that all the candidates are real, the LAE number density at z=7 is significantly lower than those at the later epochs z=5.7 and 6.6 to the limit of L(Ly-alpha) ~ 6 x 1042 erg/s.
This number deficit might reflect the larger neutral hydrogen fraction at z=7, supporting the late reionization suggested by the previous surveys of z=5.7-7 LAEs, z~6 quasars and z>6 gamma-ray bursts.
I will also present the constraint on the stellar population of a z=6.96 LAE (IOK-1) using the Spitzer mid-infrared imaging of the Subaru Deep Field and its implication for galaxy evolution and reionization.