Measurement of galaxy clustering at z ∼ 7.2 and the evolution of galaxy bias from 3.8 < z < 8 in the XDF, GOODS-S, and GOODS-N
- School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia)
- Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Cambridge (United Kingdom)
- Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands)
- UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
- Institute for Astronomy, ETH Zurich, 8092 Zurich (Switzerland)
- Department of Radiology, Mayo Clinic, Rochester, MN 55905 (United States)
- Space Telescope Science Institute, Baltimore, MD 21218 (United States)
- Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
Lyman-break galaxy (LBG) samples observed during reionization (z ≳ 6) with the Hubble Space Telescope's Wide Field Camera 3 are reaching sizes sufficient to characterize their clustering properties. Using a combined catalog from the Hubble eXtreme Deep Field and CANDELS surveys, containing N = 743 LBG candidates at z ≥ 6.5 at a mean redshift of z-bar =7.2, we detect a clear clustering signal in the angular correlation function (ACF) at ≳ 4σ, corresponding to a real-space correlation length r{sub 0}=6.7{sub −1.0}{sup +0.9}h{sup −1}cMpc. The derived galaxy bias b=8.6{sub −1.0}{sup +0.9} is that of dark matter halos of M=10{sup 11.1{sub −}{sub 0}{sub .}{sub 3}{sup +{sup 0{sup .{sup 2}}}}} M{sub ⊙} at z = 7.2, and highlights that galaxies below the current detection limit (M{sub AB} ∼ –17.7) are expected in lower-mass halos (M ∼ 10{sup 8}-10{sup 10.5} M{sub ⊙} ). We compute the ACF of LBGs at z ∼ 3.8 – z ∼ 5.9 in the same surveys. A trend of increasing bias is found from z-bar =3.8 (b ∼ 3.0) to z-bar =7.2 (b ∼ 8.6), broadly consistent with galaxies at fixed luminosity being hosted in dark matter halos of similar mass at 4 ≲ z ≲ 6, followed by a slight rise in halo masses at z ≳ 7 (∼2σ confidence). Separating the data at the median luminosity of the z-bar =7.2 sample (M {sub UV} = –19.4) shows higher clustering at z-bar =5.9 for bright galaxies (r{sub 0}=5.5{sub −1.6}{sup +1.4}h{sup −1}cMpc, b=6.2{sub −1.5}{sup +1.2}) compared to faint galaxies (r{sub 0}=1.9{sub −1.0}{sup +1.1}h{sup −1}cMpc, b=2.7{sub −1.2}{sup +1.2}) implying a constant mass-to-light ratio (dlogM/dlogL)∼1.2{sub −0.8}{sup +1.8}. A similar trend is present in the z-bar =7.2 sample with larger uncertainty. Finally, our bias measurements allow us to investigate the fraction of dark matter halos hosting UV-bright galaxies (the duty cycle, ε{sub DC}). At z-bar =7.2 values near unity are preferred, which may be explained by the shortened halo assembly time at high redshift.
- OSTI ID:
- 22365041
- Journal Information:
- Astrophysical Journal, Vol. 793, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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