Observational Studies of Galaxy Formation and Cosmic Reionization: Progresses and Problems（銀河形成と宇宙再電離：現状と課題）

大内 正己
東京大学 宇宙線研究所

I review the recent progresses in observational studies about galaxy formation and cosmic reionization, focusing on results from our group. Nowadays, deep optical and near-infrared observations with Hubble Space Telescope and 10m-class ground-based telescopes photometrically identify and spectroscopically confirm galaxies up to z~10. Evolution of major galaxy quantities (incl. abundance and morphology) is revealed at this redshift range. Although there exist large uncertainties in physical parameters, most of observational results suggest that star-forming galaxies at z>6 are major sources of cosmic reionization. Interestingly, the four independent observational measurements of the cosmic star-formation rate density, stellar mass density, metal abundance, and CMB Thomson scattering optical depth are consistently explained with simple physical equations, indicating that a rough observational picture of galaxy formation and cosmic reionization may be established. I finally discuss open questions about galaxy formation and our planned observations with next generation telescopes, especially with James Webb Space Telescope.

Place: 2F Conf. room / 研究管理棟２階会議場（1236号室）