Galaxy-Dark Matter Halo Connection at z=0-7 Revealed by the Subaru/Hyper Suprime-Cam and Hubble Surveys

Yuichi Harikane

We present clustering analysis results from 342,395 Lyman break galaxies (LBGs) at z~4-7 identified in the Subaru/Hyper Suprime-Cam SSP and Hubble legacy surveys. This sample is ~10 times larger than previous studies, and we measure the angular correlation functions (ACFs) of these LBGs at z~4, 5, 6, and 7. The measured ACFs show clear dependence on the UV magnitude (MUV) in a wide MUV range (-22 < MUV < -18) at all redshifts with significant 1 halo terms. We fit the ACFs using halo occupation distribution (HOD) models that provide an estimate of halo masses, M_h~(1-40)x10^11 Msun. We calculate stellar-to-halo mass ratios (SHMRs) of LBGs, and investigate their dependence on the halo mass and redshift. The z~4 SHMR tentatively has a peak at Mh~10^12 Msun, implying inefficient gas cooling and/or AGN feedback at the high mass (Mh > 10^12 Msun) halos. By comparison with the z~0 SHMR, we identify evolution of the SHMR from z~0 to 4, and z~4 to 7 at the >98% confidence levels. The SHMR decreases by a factor of ~2 from z~0 to 4, and increases by a factor of ~4 from z~4 to 7 at M_h~10^11 Msun. We compare our SHMRs with results of a hydrodynamic simulation and a semi-analytic model, and find that these theoretical studies do not predict the SHMR increase from z~4 to 7. This discrepancy indicates that star formation could be more efficient at the high redshift than expected in the theoretical studies.