2018/02/19 by Keven Ren, Michele Trenti, Simon J. Mutch
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Cosmology and Gravitation Theories #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Halo #Halo mass function #Luminosity #Luminosity function #Physics #Redshift #Reionization #Sigma #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aab094
12 pages, 7 figures, 1 table; accepted for publication in ApJ
arxiv created 2018/02/19 · openalex publication_date 2018/03/20 · arxiv updated 2018/04/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The most luminous galaxies at high redshift are generally considered to be hosted in massive dark-matter halos of comparable number density, hence residing at the center of over-densities/protoclusters. We assess the validity of this assumption by investigating the clustering around the brightest galaxies populating the cosmic web at redshift z ∼ 8–9 through a combination of semi-analytic modeling and Monte Carlo simulations of mock Hubble Space Telescope WFC3 observations. The innovative aspect of our approach is the inclusion of a log-normal scatter parameter Σ in the galaxy luminosity versus halo mass relation, extending the conditional luminosity function framework extensively used at low redshift to high z . Our analysis shows that the larger the value of Σ, the less likely it is that the brightest source in a given volume is hosted in the most massive halo, and hence the weaker the overdensity of neighbors. We derive a minimum value of Σ as a function of redshift by considering stochasticity in the halo assembly times, which affects galaxy ages and star formation rates in our modeling. We show that Σ min ( z ) ∼ 0.15–0.3, with Σ min increasing with redshift as a consequence of shorter halo assembly periods at higher redshifts. Current observations ( m AB ∼ 27) of the environment of spectroscopically confirmed bright sources at z > 7.5 do not show strong evidence of clustering and are consistent with our modeling predictions for Σ ≥ Σ min . Deeper future observations reaching m AB ∼ 28.2–29 would have the opportunity to clearly quantify the clustering strength and hence to constrain Σ, investigating the physical processes that drive star formation in the early universe.