Lyman-break Galaxies at z ∼ 3 in the Subaru Deep Field: Luminosity Function, Clustering, and [O iii] Emission

Abstract

We combined deep U -band imaging from the KPNO-4m/MOSAIC camera with very deep multiwaveband imaging data from optical to near-infrared wavelengths, to select Lyman Break Galaxies (LBGs) at z ∼ 3 using U − V and V − R c colors in the Subaru Deep Field. With the resulting sample of 5161 LBGs, we construct the UV luminosity function down to M UV = −18 and find a steep faint-end slope of α = −1.78 ± 0.05. We analyze rest-frame UV-to-NIR spectral energy distributions (SEDs) generated from the median optical photometry and photometry on median-composite IR images (formed from stacks around the optical positions of LBGs). In the stacks of faint LBGs, we find a systematic background depression centered on the position of the galaxy. A series of experiments confirmed our view that this deficit results from the systematic difficulty of SExtractor (or any other object-finding routine) in finding faint galaxies in regions with higher-than-average surface densities of foreground galaxies. We corrected our stacked magnitudes for this effect and suggest that other stacking studies should also make such corrections. Best-fit stellar population templates for the stacked LBG SEDs indicate stellar masses and star-formation rates (SFRs) of log 10 (M * /M ⊙ ) ≃ 10 and ≃ 50 M ⊙ yr 1500Å (rest-frame) in the faintest bin. Such strong [OIII] emission is seen only in a miniscule fraction of the most extreme local emission-line galaxies, but it probably universal in the faint galaxies that reionized the universe. This finding has strong implications for finding and studying the most common galaxies at high redshifts with upcoming surveys. Finally, we analyze clustering by computing the angular correlation function and performing halo occupation distribution (HOD) analysis. We find a mean dark halo mass of log 10 ( M h /h −1 M ⊙ ) = 11.29 ± 0.12 for the full sample of LBGs, and log 10 ( M h /h −1 M ⊙ ) = 11.49±0.1 for the brightest half of the sample. The results support the notion that more massive dark matter halos host more luminous LBGs.

Synergies between radio, optical and microwave observations at high redshift

“…u-band dropouts for z ∼ 3, g-band dropouts for z ∼ 4 and r-band dropouts for z ∼ 5 [20,65]. Magnitude limited dropout samples naturally produce bands in redshift of about ∆z ∼ 0.5 with clustering properties that are similar to normal galaxies at z = 0 [20,21,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]. Spectroscopic follow-up of such samples is challenging, but possible for the brighter objects with existing or planned facilities (see later).…”

“…Taking the UV-luminosity functions from Refs. [71], [78] and [80] for z 2, 3 and 4, we assume galaxies above a given apparent magnitude M U V populate the centers of halos with a soft mass cut from below given by an error function centered at some M min (M U V ) (see Section 6.2 of Ref. [78] for relevant formulae).…”

The dominant origin of diffuse Lyα halos around Lyα emitters explored by spectral energy distribution fitting and clustering analysis

“…We use 810 LAEs (∼ 91% of the entire sample, 891) that have data in all ten broadband filters (B, V, R, i, z, J, H, K, ch1, and ch2). To obtain secure IRAC photometry, some prescriptions are adopted in previous studies (e.g., Vargas et al 2014;Kusakabe et al 2018;Malkan et al 2017). In this paper, we follow Kusakabe et al (2018) and only use LAEs that are not contaminated by other objects in the ch1 and ch2 images.…”

Cosmology with dropout selection: straw-man surveys & CMB lensing

“…Triangles indicate the raw counts at the quoted magnitude limits from refs. [79,103,135]. From the contamination corrected counts (squares), it is clear that the fractional contamination largely occurs at the bright end.…”