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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 710133.0, MPI für Astronomie / Publikationen_mpia
The nature of Extreme Emission Line Galaxies at z = 1-2: kinematics and metallicities from near-infrared spectroscopy
Authors:Maseda, M. V.; van der Wel, A.; Rix, H.-W.; da Cunha, E.; Pacifici, C.; Momcheva, I.; Brammer, G. B.; Meidt, S. E.; Franx, M.; van Dokkum, P.; Fumagalli, M.; Bell, E. F.; Ferguson, H. C.; Förster-Schreiber, N. M.; Koekemoer, A. M.; Koo, D. C.; Lundgren, B. F.; Marchesini, D.; Nelson, E. J.; Patel, S. G.; Skelton, R. E.; Straughn, A. N.; Trump, J. R.; Whitaker, K. E.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:The Astrophysical Journal
Issue / Number:1
Start Page:id. 17 (17 pp)
Audience:Not Specified
Abstract / Description:We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M sstarf = 108-109 M &sun;) galaxies undergoing intense starburst episodes (M sstarf/SFR ~ 10-100 Myr). The sample is selected by [O III] or Halpha emission line flux and equivalent width using near-infrared grism spectroscopy from the 3D-HST survey. High-resolution NIR spectroscopy is obtained with LBT/LUCI and VLT/X-SHOOTER. The [O III]/Hbeta line ratio is high (gsim 5) and [N II]/Halpha is always significantly below unity, which suggests a low gas-phase metallicity. We are able to determine gas-phase metallicities for seven of our objects using various strong-line methods, with values in the range 0.05-0.30 Z &sun; and with a median of 0.15 Z &sun; for three of these objects we detect [O III] lambda4363, which allows for a direct constraint on the metallicity. The velocity dispersion, as measured from the nebular emission lines, is typically ~50 km s-1. Combined with the observed star-forming activity, the Jeans and Toomre stability criteria imply that the gas fraction must be large (f gas >~ 2/3), consistent with the difference between our dynamical and stellar mass estimates. The implied gas depletion timescale (several hundred Myr) is substantially longer than the inferred mass-weighted ages (~50 Myr), which further supports the emerging picture that most stars in low-mass galaxies form in short, intense bursts of star formation. This work is based on observations taken by the 3D-HST Treasury Program and the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. X-Shooter observations were performed at the European Southern Observatory, Chile, Program 089.B-0236(A).
Free Keywords:galaxies: dwarf; galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: starburst
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.1088/0004-637X/791/1/17
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