3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847

Journal Article · Wed Oct 10 00:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/758/1/L17· OSTI ID:22078505

Brammer, Gabriel B; Sanchez-Janssen, Ruben ^[1]; Labbe, Ivo; Franx, Marijn; Fumagalli, Mattia; Patel, Shannon ^[2]; Da Cunha, Elisabete; Rix, Hans-Walter; Schmidt, Kasper B; Van der Wel, Arjen ^[3]; Erb, Dawn K ^[4]; Lundgren, Britt; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E; Van Dokkum, Pieter G; Wake, David A; Whitaker, Katherine E ^[5]; Marchesini, Danilo ^[6]; Quadri, Ryan ^[7]

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1. European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile)
2. Leiden Observatory, Leiden University, 2300-RA Leiden (Netherlands)
3. Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany)
4. Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)
5. Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
6. Physics and Astronomy Department, Tufts University, Robinson Hall, Room 257, Medford, MA 02155 (United States)
7. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] {lambda}5007 and H{beta} emission lines with rest-frame equivalent widths of 2000 {+-} 100 and 520 {+-} 40 A, respectively. The source has a stellar mass {approx}10{sup 8} M{sub Sun }, sSFR {approx} 100 Gyr{sup -1}, and detection of [O III] {lambda}4363 yields a metallicity of 12 + log (O/H) = 7.5 {+-} 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size r{sub e} {approx}300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.

• OSTI ID: 22078505
• Journal Information: Astrophysical Journal Letters, Vol. 758, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COLOR
COSMIC DUST
DWARF STARS
ENERGY SPECTRA
GALAXIES
GALAXY NUCLEI
GRAVITATIONAL LENSES
INFRARED SPECTRA
MORPHOLOGY
RED SHIFT
SKY
SPATIAL RESOLUTION
TELESCOPES
WAVELENGTHS