Mainali, R;
Stark, DP;
Jones, T;
Ellis, RS;
Hezaveh, YD;
Rigby, JR;
(2023)
Spectroscopy of CASSOWARY gravitationally lensed galaxies in SDSS: characterization of an extremely bright reionization-era analogue at z = 1.42.
Monthly Notices of the Royal Astronomical Society
, 520
(3)
pp. 4037-4056.
10.1093/mnras/stad387.
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Abstract
We present new observations of 16 bright (r = 19–21) gravitationally lensed galaxies at z 1–3 selected from the CASSOWARY survey. Included in our sample is the z = 1.42 galaxy CSWA-141, one of the brightest known reionization-era analogues at high redshift (g = 20.5), with a large specific star formation rate (31.2 Gyr−1) and an [O III]+H β equivalent width (EW[O III] + H β = 730 Å) that is nearly identical to the average value expected at z 7–8. In this paper, we investigate the rest-frame UV nebular line emission in our sample with the goal of understanding the factors that regulate strong C III] emission. Although most of the sources in our sample show weak UV line emission, we find elevated C III] in the spectrum of CSWA-141 (EWC III] = 4.6 ± 1.9 Å) together with detections of other prominent emission lines (O III], Si III], Fe II, Mg II). We compare the rest-optical line properties of high-redshift galaxies with strong and weak C III] emission, and find that systems with the strongest UV line emission tend to have young stellar populations and nebular gas that is moderately metal-poor and highly ionized, consistent with trends seen at low and high redshift. The brightness of CSWA-141 enables detailed investigation of the extreme emission line galaxies which become common at z > 6. We find that gas traced by the C III] doublet likely probes higher densities than that traced by [O II] and [S II]. Characterization of the spectrally resolved Mg II emission line and several low-ionization absorption lines suggests neutral gas around the young stars is likely optically thin, potentially facilitating the escape of ionizing radiation.
| Type: | Article |
|---|---|
| Title: | Spectroscopy of CASSOWARY gravitationally lensed galaxies in SDSS: characterization of an extremely bright reionization-era analogue at z = 1.42 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad387 |
| Publisher version: | https://doi.org/10.1093/mnras/stad387 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Galaxies: evolution, galaxies: formation, galaxies: high-redshift |
| 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-pp.ucl.ac.uk/id/eprint/10171176 |
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