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Abstract We conduct a systematic search for high-redshift galaxy overdensities at 4.9 OIII λ 5008 around the best-fit photometric redshift. The rest-ultraviolet magnitudes and continuum slopes of these galaxies were inferred from the photometry: the brightest and reddest objects appear in more dense environments and thus are surrounded by more galaxy neighbors than their fainter and bluer counterparts, suggesting accelerated galaxy evolution within overdense environments. We find 17 significant ( δ gal ≥ 3.04, N gal ≥ 4) galaxy overdensities across both fields (seven in GOODS-N and 10 in GOODS-S), including the two highest redshift spectroscopically confirmed galaxy overdensities to date at z spec = 7.954 and z spec = 8.222 (representing densities around ∼6 and ∼12 times that of a random volume). We estimate the total halo mass of these large-scale structures to be 11.5 ≤ log 10 M halo / M ⊙ ≤ 13.4 using an empirical stellar mass-to-halo mass relation, which are likely underestimates as a result of incompleteness. These protocluster candidates are expected to evolve into massive galaxy clusters with log 10 M halo / M ⊙ ≳ 14 by z = 0.
Helton et al. (Tue,) studied this question.