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Title: Early-type galaxies at intermediate redshift observed with Hubble space telescope WFC3: perspectives on recent star formation

We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 ≲ z ≲ 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one- and two-component synthetic stellar models to the ETGs UV-optical-near-IR spectral energy distributions and find that a large fraction (∼40%) are likely to have experienced a minor (f{sub YC} ≲ 10% of stellar mass) burst of recent (t{sub YC} ≲ 1 Gyr) star formation. The measured age and mass fraction of the young stellar populations do not strongly trend with measurements of galaxy morphology. We note that massive (M > 10{sup 10.5} M {sub ☉}) recent star-forming ETGs appear to have larger sizes. Furthermore, high-mass, quiescent ETGs identified with likely companions populate a distinct region in the size-mass parameter space, in comparison with the distribution of massive ETGs with evidence of recent star formation (RSF). We conclude that both mechanisms of quenching star formation in disk-like ETGs and (gas-rich, minor) merger activity contribute to the formation of young stars and the size-mass evolution of intermediate redshift ETGs. The number of ETGs for which wemore » have both HST WFC3 panchromatic (especially UV) imaging and spectroscopically confirmed redshifts is relatively small, therefore, a conclusion about the relative roles of both of these mechanisms remains an open question.« less
Authors:
 [1] ; ;  [2] ; ;  [3] ;  [4] ; ;  [5] ;  [6] ;  [7]
  1. Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)
  2. Department of Astronomy, Yonsei University 134, Shinchon-dong, Sudaemun-gu, Seoul 120-179 (Korea, Republic of)
  3. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States)
  4. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom)
  5. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  6. Aix Marseille Université, CNRS, LAM, UMR 7326, F-13388, Marseille (France)
  7. Research School of Physics and Astronomy, The Australian National University, Canberra, ACT 2611 (Australia)
Publication Date:
OSTI Identifier:
22370144
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 796; 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; COMPARATIVE EVALUATIONS; DISTRIBUTION; ENERGY SPECTRA; GALAXIES; MASS; RED SHIFT; SPACE; STAR EVOLUTION; STARS; TELESCOPES; ULTRAVIOLET RADIATION