LBG ｓ at z~5 K. Ohta (Kyoto Univ.) with I. Iwata (NAOJ, Okayama) M. Ando (Kyoto Univ.) M. Akiyama (NAOJ, Subaru) N. Tamura (Durham, UK) K. Aoki (NAOJ, Subaru)

LBG search at GOODS-N and J fields V, I_c, z’ ; z~5 with S-Cam/Subaru Highest redshift achieved with two-color diagram using standard filter system Age of 1Gyr and 1Gyr earlier from z~3

Two-color diagram

Resulting UV LF at z~5

Number density of luminous LBGs does not change so much from z=5 to 3 Fainter LBGs increase at the later epoch Luminosity-dependent evolution? However…. Disagreement among UVLFs at z~4, 5 in a luminous part

Example of UV spectra of z~5 LBGs Ando et al. 2004

Composite spectrum of z~5 LBGs (vs z~3 LBG)

Ly alpha EW vs UV luminosity at z~5 Dusty environment in luminous LBGs?

Lack of blue luminous LBGs?

Downsizing of LBGs? Number density of luminous LBGs does not change so much from z=5 to 3 Fainter LBGs at z~3 are late comers? Luminous z~5 LBGs in dusty environment? chemically evolved to some degree? => lack of blue luminous ones? Luminous z~5 LBGs show larger clustering amp. luminous LBGs reside in massive DHs? => SF started eariler?

Large sample of luminous LBGs will be obtained from COSMOS