Spatially resolved HST grism spectroscopy of a lensed emission line galaxy at z ∼ 1

Brenda L. Frye, Mairead Hurley, David V. Bowen, Gerhardt Meurer, Keren Sharon, Amber Straughn, Dan Coe, Tom Broadhurst, Puragra Guhathakurta

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16 Scopus citations


We take advantage of gravitational lensing amplification by A1689 (z = 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i 775 = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of ≈4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M* ≈ 2 × 109 M ) with a high specific star formation rate (≈20Gyr -1). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 ± 0.2). We break the continuous line-emitting region of this giant arc into seven ∼1kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by ∼1kpc have a placement on the blue H II region excitation diagram with f ([O III])/f(Hβ) and f ([Ne III])/f(Hβ) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction.

Original languageEnglish (US)
Article number17
JournalAstrophysical Journal
Issue number1
StatePublished - Jul 20 2012

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • cosmology: observations
  • galaxies: clusters: general
  • galaxies: clusters: individual (A1689)
  • galaxies: distances and redshifts
  • galaxies: fundamental parameters


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