EVOLUTION OF STELLAR-TO-HALO MASS RATIO AT z = 0–7 IDENTIFIED BY CLUSTERING ANALYSIS WITH THE HUBBLE LEGACY IMAGING AND EARLY SUBARU/HYPER SUPRIME-CAM SURVEY DATA

Abstract

ABSTRACT We present clustering analysis results from 10,381 Lyman break galaxies (LBGs) at z ∼ 4–7, identified in the Hubble legacy deep imaging and new complimentary large-area Subaru/Hyper Suprime-Cam data. We measure the angular correlation functions of these LBGs at z ∼ 4, 5, 6, and 7 and fit these measurements using halo occupation distribution (HOD) models that provide an estimate of halo masses, M h ∼ ( 1 − 20 ) × 10 11 M ⊙ . Our M h estimates agree with those obtained by previous clustering studies in a UV-magnitude versus M h plane and allow us to calculate stellar-to-halo mass ratios (SHMRs) of LBGs. By comparison with the z ∼ 0 SHMR, we identify evolution of the SHMR from z ∼ 0 to z ∼ 4 and from z ∼ 4 to z ∼ 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 the dark matter halo mass of M h ∼ 10 11 M ⊙ . We compare our SHMRs with results of a hydrodynamic simulation and a semianalytic model and find that these theoretical studies do not predict the SHMR increase from z ∼ 4 to 7. We obtain the baryon conversion efficiency (BCE) of LBGs at z ∼ 4 and find that the BCE increases with increasing dark matter halo mass. Finally, we compare our clustering+HOD estimates with results from abundance matching techniques and conclude that the M h estimates of the clustering+HOD analyses agree with those of the simple abundance matching within a factor of 3, and that the agreement improves when using more sophisticated abundance matching techniques that include subhalos, incompleteness, and/or evolution in the star formation and stellar mass functions.