Cunningham, MH;
Saxena, A;
Ellis, RS;
Pentericci, L;
(2024)
C III] λ1909 emission as an alternative to Ly α in the reionization era: the dependence of C III] and Ly α at 3 < z < 4 from the VANDELS survey.
Monthly Notices of the Royal Astronomical Society
, 530
(2)
pp. 1592-1602.
10.1093/mnras/stae939.
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Abstract
The velocity offset of Ly α emission from a galaxy’s systemic redshift is an excellent tracer of conditions that enable the escape of Ly α photons from the galaxy, and potentially the all-important hydrogen ionizing Lyman continuum photons. However at z ≥ 6, Ly α is often heavily attenuated by the neutral intergalactic medium. Here we investigate the utility of C III] λλ1907, 1909 emission, usually the brightest ultraviolet (UV) line after Ly α, as a proxy estimating the Ly α velocity offset (ΔvLy α). To do so, we use analogues of reionization era galaxies based upon 52 star-forming galaxies with robust C III] detections drawn from the VANDELS survey. Our sample spans a broad UV magnitude range of −18.5 < MUV < −22.0, with a sample average value of EW(C III]) = 5.3 Å. We find a slight increase of EW(C III]) with increasing EW(Ly α), but find a large range of EW(C III]) ∼ 1–13 Å particularly at EW(Ly α) < 10 Å. Using the C III] line peak as the systemic redshift, we calculate ΔvLy α and recover the previously reported trend of decreasing ΔvLy α with increasing EW(Ly α). Interestingly, we find an anticorrelation between ΔvLy α and EW(C III]), which also displays a dependence on the UV absolute magnitude. We derive a multivariate fit to obtain ΔvLy α using both EW(C III]) and MUV, finding that ΔvLy α is more strongly dependent on EW(C III]), with a weaker but non-negligible dependence on MUV. We find that for a fixed EW(C III]), UV-bright Ly α emitting galaxies show smaller values of ΔvLy α,which suggests that such galaxies may be undergoing more bursty star-formation compared to the UV-fainter ones, akin to a population of extremely UV-bright galaxies identified at z > 10.
| Type: | Article |
|---|---|
| Title: | C III] λ1909 emission as an alternative to Ly α in the reionization era: the dependence of C III] and Ly α at 3 < z < 4 from the VANDELS survey |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stae939 |
| Publisher version: | https://doi.org/10.1093/mnras/stae939 |
| Language: | English |
| Additional information: | Copyright © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | galaxies: evolution; 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.ucl.ac.uk/id/eprint/10191261 |
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