skip to main content

Title: Atomic data for S II—toward better diagnostics of chemical evolution in high-redshift galaxies

Absorption-line spectroscopy is a powerful tool used to estimate element abundances in both the nearby and distant universe. The accuracy of the abundances thus derived is naturally limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state of the art quantal calculations. Here, we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and sub-DLA absorber galaxies detected in the spectra of quasars and gamma-ray bursts. We report new extensive calculations of a large number of energy levels of S II, and the line strengths of the resulting radiative transitions. Our calculations are based on the configuration interaction approach within a numerical Hartree-Fock framework, and utilize both non-relativistic and quasirelativistic one-electron radial orbitals. The results of these new atomic calculations are then incorporated into Cloudy and applied to a lab plasma, and a typical DLA, for illustrative purposes. The new results imply relatively modest changes (≈0.04 dex) to the metallicities estimated from S IImore » in past studies. These results will be readily applicable to other studies of S II in the Milky Way and other galaxies.« less
Authors:
;  [1] ;  [2] ; ;  [3]
  1. Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, LT-01108 (Lithuania)
  2. Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 (United States)
  3. Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)
Publication Date:
OSTI Identifier:
22348291
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; 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; ABSORPTION; ACCURACY; CONFIGURATION INTERACTION; COSMIC GAMMA BURSTS; ELECTRONS; ELEMENT ABUNDANCE; EVOLUTION; HARTREE-FOCK METHOD; METALLICITY; MILKY WAY; QUASARS; RED SHIFT; RELATIVISTIC RANGE; SIMULATION; SPECTRA; SPECTROSCOPY; UNIVERSE