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Title: The physical conditions, metallicity and metal abundance ratios in a highly magnified galaxy at z = 3.6252

We present optical and near-IR imaging and spectroscopy of SGAS J105039.6+001730, a strongly lensed galaxy at z = 3.6252 magnified by >30×, and derive its physical properties. We measure a stellar mass of log(M{sub *}/M{sub ☉}) = 9.5 ± 0.35, star formation rates from [O II] λλ3727 and Hβ of 55 ± 25 and 84 ± 24 M{sub ☉} yr{sup –1}, respectively, an electron density of n{sub e} ≤ 10{sup 3} cm{sup –2}, an electron temperature of T{sub e} ≤ 14,000 K, and a metallicity of 12 + log(O/H) = 8.3 ± 0.1. The strong C III] λλ1907,1909 emission and abundance ratios of C, N, O, and Si are consistent with well-studied starbursts at z ∼ 0 with similar metallicities. Strong P Cygni lines and He II λ1640 emission indicate a significant population of Wolf-Rayet stars, but synthetic spectra of individual populations of young, hot stars do not reproduce the observed integrated P Cygni absorption features. The rest-frame UV spectral features are indicative of a young starburst with high ionization, implying either (1) an ionization parameter significantly higher than suggested by rest-frame optical nebular lines, or (2) differences in one or both of the initial mass function and the propertiesmore » of ionizing spectra of massive stars. We argue that the observed features are likely the result of a superposition of star forming regions with different physical properties. These results demonstrate the complexity of star formation on scales smaller than individual galaxies, and highlight the importance of systematic effects that result from smearing together the signatures of individual star forming regions within galaxies.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ; ;  [5] ;  [6]
  1. Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States)
  2. Observational Cosmology Lab, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  3. Department of Astronomy, The University of Michigan, 500 Church Street Ann Arbor, MI 48109 (United States)
  4. Max Plank Institute for Extraterrestrial Physics, Gießenbachstrae, D-85741 Garching bei München (Germany)
  5. Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  6. Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan)
Publication Date:
OSTI Identifier:
22365461
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; 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; ABSORPTION; ABUNDANCE; ELECTRON DENSITY; ELECTRON TEMPERATURE; EMISSION; GALAXIES; GRAVITATIONAL LENSES; MASS; METALLICITY; METALS; NEAR INFRARED RADIATION; RED SHIFT; SPECTRA; SPECTROSCOPY; VISIBLE RADIATION; WOLF-RAYET STARS