GOLDRUSH. II. Clustering of galaxies at z ∼ 4-6 revealed with the half-million dropouts over the 100 deg2 area corresponding to 1 Gpc3
Abstract
We present clustering properties from 579492 Lyman-break galaxies (LBGs) at z ∼ 4-6 over the 100 deg2 sky (corresponding to a 1.4 Gpc3 volume) identified in early data of the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. We derive angular correlation functions (ACFs) for the HSC LBGs with unprecedentedly high statistical accuracies at z ∼ 4-6, and compare them with the halo occupation distribution (HOD) models. We clearly identify significant ACF excesses in 10″ < θ < 90″, the transition scale between one- and two-halo terms, suggestive of the existence of the non-linear halo bias effect. Combining the HOD models and previous clustering measurements of faint LBGs at z ∼ 4-7, we investigate the dark matter halo mass (Mh) of the z ∼ 4-7 LBGs and its correlation with various physical properties including the star formation rate (SFR), the stellar-to-halo mass ratio (SHMR), and the dark matter accretion rate (\dot{M}_{ h}) over a wide mass range of Mh/M⊙ = 4 × 1010-4 × 1012. We find that the SHMR increases from z ∼ 4 to 7 by a factor of ∼4 at Mh ≃ 1 × 1011 M⊙ , while the SHMR shows no strong evolution in the similar redshift range at Mh ≃ 1 × 1012 M⊙ . Interestingly, we identify a tight relation of SFR/\dot{M}_{ h}-Mh showing no significant evolution beyond 0.15 dex in this wide mass range over z ∼ 4-7. This weak evolution suggests that the SFR/\dot{M}_{ h}-Mh relation is a fundamental relation in high-redshift galaxy formation whose star formation activities are regulated by the dark matter mass assembly. Assuming this fundamental relation, we calculate the cosmic star formation rate densities (SFRDs) over z = 0-10 (a.k.a. the Madau-Lilly plot). The cosmic SFRD evolution based on the fundamental relation agrees with the one obtained by observations, suggesting that the cosmic SFRD increase from z ∼ 10 to 4 - 2 (decrease from z ∼ 4-2 to 0) is mainly driven by the increase of the halo abundance (the decrease of the accretion rate).
- Publication:
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Publications of the Astronomical Society of Japan
- Pub Date:
- January 2018
- DOI:
- 10.1093/pasj/psx097
- arXiv:
- arXiv:1704.06535
- Bibcode:
- 2018PASJ...70S..11H
- Keywords:
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- galaxies: evolution;
- galaxies: formation;
- galaxies: high-redshift;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 34 pages, 27 figures, PASJ in press