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Discovery of a z = 7.452 High Equivalent Width Lyman-α Emitter from the Hubble Space Telescope Faint Infrared Grism Survey

Larson, RL; Finkelstein, SL; Pirzkal, N; Ryan, R; Tilvi, V; Malhotra, S; Rhoads, J; ... Team, TFIGS; + view all (2018) Discovery of a z = 7.452 High Equivalent Width Lyman-α Emitter from the Hubble Space Telescope Faint Infrared Grism Survey. The Astrophysical Journal , 858 (2) 10.3847/1538-4357/aab893. Green open access

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Abstract

We present the results of an unbiased search for Lyα emission from continuum-selected 5.6 < z < 8.7 galaxies. Our data set consists of 160 orbits of G102 slitless grism spectroscopy obtained with the Hubble Space Telescope(HST)/WFC3 as part of the Faint Infrared Grism Survey (FIGS; PI: Malhotra), which obtains deep slitless spectra of all sources in four fields, and was designed to minimize contamination in observations of previously identified high-redshift galaxy candidates. The FIGS data can potentially spectroscopically confirm the redshifts of galaxies, and as Lyα emission is resonantly scattered by neutral gas, FIGS can also constrain the ionization state of the intergalactic medium during the epoch of reionization. These data have sufficient depth to detect Lyα emission in this epoch, as Tilvi et al. have published the FIGS detection of previously known Lyα emission at z = 7.51. The FIGS data use five separate roll angles of HST to mitigate the contamination by nearby galaxies. We created a method that accounts for and removes the contamination from surrounding galaxies and also removes any dispersed continuum light from each individual spectrum. We searched for significant (>4σ) emission lines using two different automated detection methods, free of any visual inspection biases. Applying these methods on photometrically selected high-redshift candidates between 5.6 < z < 8.7, we find two emission lines, one previously published by Tilvi et al., (2016) and a new line at 1.028 μm, which we identify as Lyα at z = 7.452 ± 0.003. This newly spectroscopically confirmed galaxy has the highest Lyα rest-frame equivalent width (EWLyα ) yet published at z > 7 (140.3 ± 19.0 Å).

Type: Article
Title: Discovery of a z = 7.452 High Equivalent Width Lyman-α Emitter from the Hubble Space Telescope Faint Infrared Grism Survey
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/aab893
Publisher version: http://dx.doi.org/10.3847/1538-4357/aab893
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: galaxies: distances and redshifts, galaxies: high-redshift, line: identification
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10055373
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