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Title: GEOMETRY OF STAR-FORMING GALAXIES FROM SDSS, 3D-HST, AND CANDELS

We determine the intrinsic, three-dimensional shape distribution of star-forming galaxies at 0 < z < 2.5, as inferred from their observed projected axis ratios. In the present-day universe, star-forming galaxies of all masses 10{sup 9}-10{sup 11} M {sub ☉} are predominantly thin, nearly oblate disks, in line with previous studies. We now extend this to higher redshifts, and find that among massive galaxies (M {sub *} > 10{sup 10} M {sub ☉}) disks are the most common geometric shape at all z ≲ 2. Lower-mass galaxies at z > 1 possess a broad range of geometric shapes: the fraction of elongated (prolate) galaxies increases toward higher redshifts and lower masses. Galaxies with stellar mass 10{sup 9} M {sub ☉} (10{sup 10} M {sub ☉}) are a mix of roughly equal numbers of elongated and disk galaxies at z ∼ 1 (z ∼ 2). This suggests that galaxies in this mass range do not yet have disks that are sustained over many orbital periods, implying that galaxies with present-day stellar mass comparable to that of the Milky Way typically first formed such sustained stellar disks at redshift z ∼ 1.5-2. Combined with constraints on the evolution of the star formation ratemore » density and the distribution of star formation over galaxies with different masses, our findings imply that, averaged over cosmic time, the majority of stars formed in disks.« less
Authors:
; ; ;  [1] ;  [2] ; ; ; ;  [3] ; ; ;  [4] ;  [5] ;  [6] ;  [7] ; ;  [8] ;  [9] ;  [10] ;  [11] more »; « less
  1. Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany)
  2. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  3. UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
  4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  5. Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States)
  6. South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa)
  7. Astrophysics Science Division, Goddard Space Center, Greenbelt, MD 20771 (United States)
  8. Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
  9. Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)
  10. Department of Theoretical Physics, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)
  11. Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 AA Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22365222
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 792; 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; COMPARATIVE EVALUATIONS; LIMITING VALUES; MASS; MILKY WAY; RED SHIFT; STAR EVOLUTION; STARS; THREE-DIMENSIONAL CALCULATIONS; UNIVERSE