EXTINCTION AND NEBULAR LINE PROPERTIES OF A HERSCHEL-SELECTED LENSED DUSTY STARBURST AT z=1.027

Nicholas Timmons*, Asantha Cooray, Hooshang Nayyeri, Caitlin Casey, Jae Calanog, Brian Ma, Hugo Messias, Maarten Baes, R. Shane Bussmann, Loretta Dunne, Simon Dye, Steve Eales, Hai Fu, R. J. Ivison, Steve Maddox, Michal J. Michalowski, I. Oteo, Dominik A. Riechers, Elisabetta Valiante, Julie Wardlow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We present Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging and grism spectroscopy observations of the Herschel-selected gravitationally lensed starburst galaxy HATLASJ1429-0028. The lensing system consists of an edge-on foreground disk galaxy at z = 0.218 with a nearly complete Einstein ring of the infrared luminous galaxy at z = 1.027. The WFC3 spectroscopy with G102 and G141 grisms, covering the wavelength range of 0.8-1.7 mu m, resulted in detections of H alpha + [NII], H beta, [SII], and [OIII] for the background galaxy from which we measure line fluxes and ratios. The Balmer line ratio H alpha/H beta of 7.5 +/- 4.4, when corrected for [NII], results in an extinction for the starburst galaxy of E(B-V)= 0.8 +/- 0.5. The H alpha-based star formation rate (SFR), when corrected for extinction, is 60 +/- 50 M-circle dot yr-1, lower than the instantaneous SFR of 390 +/- 90 M-circle dot yr-1 from the total IR luminosity. We also compare the nebular line ratios of HATLASJ1429-0028 with other star-forming and submillimeter bright galaxies. The nebular line ratios are consistent with an intrinsic ultra-luminous infrared galaxy with no evidence for excitation by an active galactic nucleus (AGN). We estimate the metallicity, 12 + log(O/H), of HATLASJ1429-0028 to be 8.49 +/- 0.16. Such a low value is below the average relation for stellar mass versus metallicity of galaxies at z similar to 1 for a galaxy with a stellar mass of similar to 2x10(11) M-circle dot. The combination of high stellar mass, the lack of AGN indicators, low metallicity, and the high SFR of HATLASJ1429-0028 suggest that this galaxy is currently undergoing a rapid formation.

Original languageEnglish
Article number140
Number of pages6
JournalAstrophysical Journal
Volume805
Issue number2
Early online date28 May 2015
DOIs
Publication statusPublished - 1 Jun 2015

Keywords

  • cosmology: observations
  • galaxies: evolution
  • infrared: galaxies
  • submillimeter: galaxies
  • STAR-FORMING GALAXIES
  • SUBMILLIMETER GALAXIES
  • HIGH-REDSHIFT
  • THAN 1.5
  • SPECTRA
  • MASS
  • SPECTROSCOPY
  • METALLICITY
  • EXTRACTION
  • SOFTWARE

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