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3D-HST grism spectroscopy of a gravitationally lensed, low-metallicity starburst galaxy at ɀ = 1.847

Brammer, Gabriel B.; Sánchez-Janssen, Rubén; Labbé, Ivo; da Cunha, Elisabete; Erb, Dawn K.; Franx, Marijn; Fumagalli, Mattia; Lundgren, Britt; Marchesini, Danilo; Momcheva, Ivelina; Nelson, Erica; Patel, Shannon; Quadri, Ryan; Rix, Hans-Walter; Skelton, Rosalind E.; Schmidt, Kasper B.; van der Wel, Arjen; van Dokkum, Pieter G.; Wake, David A. and Whitaker, Katherine E. (2012). 3D-HST grism spectroscopy of a gravitationally lensed, low-metallicity starburst galaxy at ɀ = 1.847. Astrophysical Journal Letters, 758(1), article no. L17.

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We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at ɀ = 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] λ5007 and Hβ emission lines with rest-frame equivalent widths of 2000 ± 100 and 520 ± 40 Å, respectively. The source has a stellar mass ~108 M , sSFR ~ 100 Gyr–1, and detection of [O III] λ4363 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 re ~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.

Item Type: Journal Item
Copyright Holders: 2012 The American Astronomical Society
ISSN: 2041-8213
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetFP7-COFUNDMarie Curie Actions of the European Commission
Not SetHIGHZ No. 227749ERC
Keywords: dwarf galaxies; galactic formation; high-redshift galaxies; starburst galaxies
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 38273
Depositing User: Astrid Peterkin
Date Deposited: 12 Sep 2013 11:30
Last Modified: 07 Dec 2018 10:18
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