The nature of extreme emission line galaxies at z = 1-2: kinematics and metallicities from near-infrared spectroscopy

Journal Article · Sun Aug 10 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/791/1/17· OSTI ID:22365425

Maseda, Michael V.; Van der Wel, Arjen; Rix, Hans-Walter; Da Cunha, Elisabete; Meidt, Sharon E. ^[1]; Pacifici, Camilla ^[2]; Momcheva, Ivelina; Van Dokkum, Pieter; Nelson, Erica J. ^[3]; Brammer, Gabriel B.; Ferguson, Henry C.; Koekemoer, Anton M. ^[4]; Franx, Marijn; Fumagalli, Mattia ^[5]; Bell, Eric F. ^[6]; Förster-Schreiber, Natascha M. ^[7]; Koo, David C. ^[8]; Lundgren, Britt F. ^[9]; Marchesini, Danilo ^[10]; others, and

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1. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
2. Yonsei University Observatory, Yonsei University, Seoul 120-749 (Korea, Republic of)
3. Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
5. Leiden Observatory, Leiden University, Leiden (Netherlands)
6. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
7. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)
8. UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)
9. Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)
10. Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States)

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{sub *} = 10{sup 8}-10{sup 9} M{sub ☉}) galaxies undergoing intense starburst episodes (M{sub *}/SFR ∼ 10-100 Myr). The sample is selected by [O III] or Hα 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]/Hβ line ratio is high (≳ 5) and [N II]/Hα 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{sub ☉} and with a median of 0.15 Z{sub ☉}; for three of these objects we detect [O III] λ4363, which allows for a direct constraint on the metallicity. The velocity dispersion, as measured from the nebular emission lines, is typically ∼50 km s{sup –1}. Combined with the observed star-forming activity, the Jeans and Toomre stability criteria imply that the gas fraction must be large (f{sub 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.

• OSTI ID: 22365425
• Journal Information: Astrophysical Journal, Vol. 791, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION SPECTROSCOPY
DATA
DISPERSIONS
EMISSION
GALAXIES
INFRARED SPECTRA
LIMITING VALUES
MASS
METALLICITY
NEAR INFRARED RADIATION
RED SHIFT
RESOLUTION
STABILITY
STARS
THREE-DIMENSIONAL CALCULATIONS
VELOCITY