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Title: Dense cores in galaxies out to z = 2.5 in SDSS, UltraVISTA, and the five 3D-HST/Candels fields

The dense interiors of massive galaxies are among the most intriguing environments in the universe. In this paper,we ask when these dense cores were formed and determine how galaxies gradually assembled around them. We select galaxies that have a stellar mass >3 × 10{sup 10} M{sub ☉} inside r = 1 kpc out to z = 2.5, using the 3D-HST survey and data at low redshift. Remarkably, the number density of galaxies with dense cores appears to have decreased from z = 2.5 to the present. This decrease is probably mostly due to stellar mass loss and the resulting adiabatic expansion, with some contribution from merging. We infer that dense cores were mostly formed at z > 2.5, consistent with their largely quiescent stellar populations. While the cores appear to form early, the galaxies in which they reside show strong evolution: their total masses increase by a factor of 2-3 from z = 2.5 to z = 0 and their effective radii increase by a factor of 5-6. As a result, the contribution of dense cores to the total mass of the galaxies in which they reside decreases from ∼50% at z = 2.5 to ∼15% at z = 0.more » Because of their early formation, the contribution of dense cores to the total stellar mass budget of the universe is a strong function of redshift. The stars in cores with M{sub 1{sub kpc}} > 3 × 10{sup 10} M{sub ☉} make up ∼0.1% of the stellar mass density of the universe today but 10%-20% at z ∼ 2, depending on their initial mass function. The formation of these cores required the conversion of ∼10{sup 11} M{sub ☉} of gas into stars within ∼1 kpc, while preventing significant star formation at larger radii.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ;  [9] ;  [10] ;  [11]
  1. Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
  2. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  3. Max Planck Institute for Astronomy (MPIA), Königstuhl 17, D-69117 Heidelberg (Germany)
  4. Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
  5. Astrophysics Science Division, Goddard Space Center, Greenbelt, MD 20771 (United States)
  6. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  7. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
  8. Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany)
  9. Leiden Observatory, Leiden University, 2300-RA Leiden (Netherlands)
  10. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
  11. Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
Publication Date:
OSTI Identifier:
22365392
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONVERSION; COSMOLOGY; DENSITY; EVOLUTION; EXPANSION; GALAXIES; MASS TRANSFER; RED SHIFT; STARS; STELLAR WINDS; UNIVERSE