NOAO >   Observing Info >   Approved Programs >   2018A-0403

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Program Information for 2018A-0403


PI: Swara Ravindranath, STScI, swara@stsci.edu
Address: 3700 SAN MARTIN DRIVE, BALTIMORE, MD 21218 USA

CoI: Michael Maseda, Leiden Observatory
CoI: Mark Dickinson, NOAO
CoI: Henry Ferguson, STScI
CoI: Jason Tumlinson, STScI
CoI: Arjen van der Wel, Max Planck Institut fur Astrophysik

Title: Semi-forbidden CIII]1909 Emission in the Rest-frame UV Spectra of Extreme Emission Line Galaxies

Abstract: We propose to use the GMOS instrument on Gemini-South to obtain the rest-frame UV spectra of Extreme Emission Line Galaxies (EELGs) at 1.4<2.4, which are actively star-forming and have extreme optical emission line ratios indicative of low metallicities. EELGs have physical conditions similar to the z>6 lensed star-forming galaxies, and are good candidates to calibrate the rest-UV diagnostics that can be applied to sources in the reionization era. We plan to observe 33 EELGs in the CANDELS COSMOS field, with the B600 grating and total integration of 8 hours on a single mask. We will use the GMOS spectra to confirm the ubiquity of the semi-forbidden CIII](190.9nm) emission line in low-mass, low-metallicity galaxies, to establish its utility as an alternative redshift indicator when Lyman-alpha emission becomes inaccessible at z>7 due to IGM absorption. We will use the data to (1) obtain empirical relations between equivalent widths of CIII] and gas phase metallicity, (2) Compare the diagnostics using CIII] and optical emission lines to the predictions from photoionization models, (3) Construct composite rest-frame UV spectra of EELGs which will serve as a useful template for studies of z>7 galaxies. We were awarded time in 2017A, but only got barely 50% of the data in non-optimal sky conditions, and the field was available only for short duration after March. The delay was mainly due to time spent on finalizing the mask, but is now already available to be re-used in early 2018A semester.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2018A):  GEM-SQ/GMOSS -- 8.8hrs band 1 (GS-2018A-Q-108 )


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NOAO >   Observing Info >   Approved Programs >   2018A-0403

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