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Title: THE GENTLE GROWTH OF GALAXIES AT HIGH REDSHIFTS IN OVERDENSE ENVIRONMENTS

We have explored prevailing modes of galaxy growth for redshifts z ∼ 6-14, comparing substantially overdense and normal regions of the universe, using high-resolution zoom-in cosmological simulations. Such rare overdense regions have been projected to host high-z quasars. We demonstrate that galaxies in such environments grow predominantly by a smooth accretion from cosmological filaments which dominates the mass input from major, intermediate, and minor mergers. We find that by z ∼ 6, the accumulated galaxy mass fraction from mergers falls short by a factor of 10 of the cumulative accretion mass for galaxies in the overdense regions, and by a factor of 5 in the normal environments. Moreover, the rate of the stellar mass input from mergers also lies below that of an in situ star formation (SF) rate. The fraction of stellar masses in galaxies contributed by mergers in overdense regions is ∼12%, and ∼33% in the normal regions, at these redshifts. Our median SF rates for ∼few × 10{sup 9} M {sub ☉} galaxies agrees well with the recently estimated rates for z ∼ 7 galaxies from Spitzer's SURF-UP survey. Finally, we find that the main difference between the normal and overdense regions lies in the amplified growthmore » of massive galaxies in massive dark matter halos. This leads to the formation of ≳ 10{sup 10} M {sub ☉} galaxies due to the ∼100 fold increase in mass during the above time period. Such galaxies are basically absent in the normal regions at these redshifts.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Argelander Institut fuer Astronomie, University of Bonn, Auf dem Haegel 71, D-53121 Bonn (Germany)
  2. Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)
  3. Department of Astronomy, University of Texas, Austin, TX 78712-1205 (United States)
  4. Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112-0830 (United States)
Publication Date:
OSTI Identifier:
22365437
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 790; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMOLOGY; FILAMENTS; GALACTIC EVOLUTION; GALAXIES; MASS; NONLUMINOUS MATTER; RED SHIFT; RESOLUTION; STARS; UNIVERSE