The HETDEX Survey Emission-line Exploration and Source Classification*

Davis, Dustin; Gebhardt, Karl; Cooper, Erin Mentuch; Ciardullo, Robin; Fabricius, Maximilian; Farrow, Daniel J.; Feldmeier, John J.; Finkelstein, Steven L.; Gawiser, Eric; Gronwall, Caryl; Hill, Gary J.; Hopp, Ulrich; House, Lindsay R.; Jeong, Donghui; Kollatschny, Wolfram; Komatsu, Eiichiro; Landriau, Martin; Liu, Chenxu; Saito, Shun; Tuttle, Sarah; Wold, Isak G. B.; Zeimann, Gregory R.; Zhang, Yechi

Abstract

The Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) is an untargeted spectroscopic survey that aims to measure the expansion rate of the universe at z ∼ 2.4 to 1% precision for both H(z) and DA(z). HETDEX is in the process of mapping in excess of one million Lyα emitting (LAE) galaxies and a similar number of lower-z galaxies as a tracer of the large-scale structure. The success of the measurement is predicated on the post-observation separation of galaxies with Lyα emission from the lower-z interloping galaxies, primarily [O ii], with low contamination and high recovery rates. The Emission Line eXplorer (ELiXer) is the principal classification tool for HETDEX, providing a tunable balance between contamination and completeness as dictated by science needs. By combining multiple selection criteria, ELiXer improves upon the 20 Å rest-frame equivalent width cut commonly used to distinguish LAEs from lower-z [O ii] emitting galaxies. Despite a spectral resolving power, R ∼ 800, that cannot resolve the [O ii] doublet, we demonstrate the ability to distinguish LAEs from foreground galaxies with 98.1% accuracy. We estimate a contamination rate of Lyα by [O ii] of 1.2% and a Lyα recovery rate of 99.1% using the default ELiXer configuration. These rates meet the HETDEX science requirements.

Citation

Davis, D., Gebhardt, K., Cooper, E. M., Ciardullo, R., Fabricius, M., Farrow, D. J., …Zhang, Y. (2023). The HETDEX Survey Emission-line Exploration and Source Classification*. The Astrophysical journal, 946(2), Article 86. https://doi.org/10.3847/1538-4357/acb0ca

• Journal Article Type: Article
• Acceptance Date: Jan 4, 2023
• Online Publication Date: Apr 3, 2023
• Publication Date: Apr 1, 2023
• Deposit Date: Apr 18, 2024
• Publicly Available Date: Apr 23, 2024
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 946
• Issue: 2
• Article Number: 86
• DOI: https://doi.org/10.3847/1538-4357/acb0ca
• Keywords: Dark energy; Emission line galaxies; Lyman-alpha galaxies; Redshift surveys
• Public URL: https://hull-repository.worktribe.com/output/4627021