Probing the Era of Galaxy Formation with Subaru Telescope

Abstract

Following rather lengthy introductory sections about big bang cosmology and high-redshift galaxies, we report the recent results for Lyman break galaxies and Lyman a emitters obtained with Subaru telescope. Based on the data of about 2600 Lyman break galaxies (LBGs) at z ∼ 4 and z ∼ 5, we find that the number density of LBGs, especially that of bright LBGs, (1) increases from z = 0 toward z = 3, and (2) remains nearly constant over z = 3 - 4, and then (3) decreases from z = 4 toward z = 5. Our new analysis based on newly obtained data of about 4500 LBGs at z ∼ 4 and about 800 LBGs at z ∼ 5 revealed that (4) faint LBGs (M > -19) at z ∼5 are as numerous as those at z ∼ 4 - 3. Large-scale structure was already present in the distribution of Lyman a emitters at z ∼ 6, and that of Lyman α emitters at z ∼ 5 shows large cosmic variance. We found two clumps of Lyman a emitters at z ∼ 6, which would be clusters in a formation phase involving a burst of galaxy formation.