TY - JOUR
T1 - Spectroscopy of CASSOWARY gravitationally lensed galaxies in SDSS
T2 - characterization of an extremely bright reionization-era analogue at z = 1.42
AU - Mainali, Ramesh
AU - Stark, Daniel P.
AU - Jones, Tucker
AU - Ellis, Richard S.
AU - Hezaveh, Yashar D.
AU - Rigby, Jane R.
N1 - Publisher Copyright: © 2023 Oxford University Press. All rights reserved.
PY - 2023/4/1
Y1 - 2023/4/1
N2 - 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.
AB - 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.
KW - galaxies: evolution
KW - galaxies: formation
KW - galaxies: high-redshift
UR - http://www.scopus.com/inward/record.url?scp=85159166169&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85159166169&partnerID=8YFLogxK
U2 - 10.1093/mnras/stad387
DO - 10.1093/mnras/stad387
M3 - Article
SN - 0035-8711
VL - 520
SP - 4037
EP - 4056
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -