Lyman-α at cosmic noon I: Lyα spectral type selection of z ∼ 2 - 3 Lyman break galaxies with broadband imaging
Abstract
High-redshift Lyman break galaxies (LBGs) are efficiently selected in deep images using as few as three broadband filters, and have been shown to have multiple intrinsic and small- to large-scale environmental properties related to Lyman- α . In this paper we demonstrate a statistical relationship between net Lyman- α equivalent width (net Ly α EW) and the optical broadband photometric properties of LBGs at z∼2 . We show that LBGs with the strongest net Ly α EW in absorption (aLBGs) and strongest net Ly α EW in emission (eLBGs) separate into overlapping but discrete distributions in (U_n-R) colour and R -band magnitude space, and use this segregation behaviour to determine photometric selection criteria by which sub-samples with a desired Ly α spectral type can be selected using data from as few as three broadband optical filters. We propose application of our result to current and future large-area and all-sky photometric surveys that will select hundreds of millions of LBGs across many hundreds to thousands of Mpc, and for which spectroscopic follow-up to obtain Ly α spectral information is prohibitive. To this end, we use spectrophotometry of composite spectra derived from a sample of 798 LBGs divided into quartiles on the basis of net Ly α EW to calculate selection criteria for the isolation of Ly α -absorbing and Ly α -emitting populations of z∼3 LBGs using ugri broadband photometric data from the Vera Rubin Observatory Legacy Survey of Space and Time (LSST).
- Publication:
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Publications of the Astronomical Society of Australia
- Pub Date:
- November 2023
- DOI:
- 10.1017/pasa.2023.48
- arXiv:
- arXiv:2311.10985
- Bibcode:
- 2023PASA...40...52F
- Keywords:
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- Galaxies: fundamental parameters;
- galaxies: photometry;
- galaxies: high-redshift;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Published in Publications of the Astronomical Society of Australia 16 pages, 6 figures, 8 tables