Early Stage of Galaxy Formation
  We discuss on the early stage of galaxy formation based on recent deep surveys for very high-redshift galaxies, mostly beyond redshift of 6. These galaxies are observed to be strong Lyman$\alpha$ emitters, indicating bursts of massive star formation in them. The fraction of such star-forming system appears to increase with increasing redshift. On the other hand, the star formation rate density derived from Lyman$\alpha$ emitters tends to decrease with increasing redshift. It is thus suggested that the major epoch of initial starbursts may occur around $z \sim$ 6 -- 7. In order to understand the early stage of galaxy formation, new surveys for galaxies beyond redshift of 7 will be important in near future. 
Y. Taniguchi, T. Nagao, M. Ajiki, Y. Shioya, S. S. Sasaki, and T.   Murayama