NOAO >   Observing Info >   Approved Programs >   2012A-0127

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Proposal Information for 2012A-0127


PI: Bethan James, Space Telescope Science Institute, bjames@stsci.edu
Address: 3700 San Martin Drive, Baltimore, MD 21218, USA

CoI: Mike Barlow, University College London
CoI: Alessandra Aloisi, Space Telescope Science Institute
CoI: Mark Westmoquette, European Southern Observatory, Garching
CoI: Tracy Beck, Space Telescope Science Institute
CoI: Oskar Karczewski, University College London

Title: The True Abundances of Star-Forming Galaxies: Ionized Gas with GMOS-IFU vs Neutral Gas with HST-COS

Abstract: Galaxy metallicity and its evolution with redshift is of paramount importance for understanding galaxy formation. ISM abundances are typically determined from HII regions that may not be typical for the whole galaxy. This is especially true for star-forming galaxies (SFGs), where the ionized-gas is more rapidly affected by chemical evolution than the more abundant neutral-gas. Quantifying the metals in both the neutral- and ionized-gas is thus important to assess how reliably HII regions trace abundances of a galaxy at any redshift. Our team has obtained HST/COS spectroscopy of the neutral-gas along the sight lines of bright UV sources in 9 nearby SFGs. Here we propose to obtain GMOS-IFU spectroscopy of 7 of these SFGs to complement our COS observations. These new GMOS-N data will allow us to spatially resolve the distribution of emission-line ratios, extinction, Te, Ne and abundances along the same sight lines of the HII regions targeted by COS. Our COS/GMOS project will be the first detailed and spatially-accurate comparison between neutral- and ionized-gas abundances in local SFGs. The results will provide new insights into the metallicity range within galaxies, with possible implications for our understanding of the observed offset between LBGs and DLA systems at higher redshift.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2012A-0127

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