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A search for H i absorption in distant star-forming galaxies with ASKAP-FLASH -I. Selection and analysis of the radio sample

Eden, Sophie L; Sadler, Elaine M; Pimbblet, Kevin A; Mahony, Elizabeth K; Yoon, Hyein

Authors

Sophie L Eden

Elaine M Sadler

Elizabeth K Mahony

Hyein Yoon



Abstract

We present and discuss two catalogues of UV-selected (NUV < 22.8 mag) galaxies that lie within a 200 deg 2 area of sky covered by the ASKAP FLASH survey and have an impact parameter of less than 20 arcsec to a FLASH radio continuum source. These catalogues are designed to enable a future search for 21 cm H i absorption in and around star-forming galaxies at redshift 0.4 < z < 1. We outline the production of this UV-bright dataset, which has optical spectroscopy from the WiggleZ and SDSS surveys and a median redshift of ∼ 0.6. Analysis of the optical spectra, using multiple diagnostic diagrams, shows that galaxies with an impact parameter of less than 5 arcsec are likely to be physically associated with the radio source and are five times more likely to be an AGN than objects without a radio match. Conversely, objects with impact factors between 5 and 20 arcsec are largely (> 80 percent) star-forming and resemble the overall WiggleZ population. The (g-i) colour evolution with redshift is consistent with a history of active star-formation, but the radio-associated objects are typically redder and have colours similar to high-excitation radio galaxies. The redshift distribution of the two catalogues matches the overall distribution for WiggleZ galaxies, despite their otherwise rare radio properties. These catalogues can be expanded in future as new radio data become available, and a forthcoming paper will present the H i absorption results.

Citation

Eden, S. L., Sadler, E. M., Pimbblet, K. A., Mahony, E. K., & Yoon, H. (2025). A search for H i absorption in distant star-forming galaxies with ASKAP-FLASH -I. Selection and analysis of the radio sample. Monthly notices of the Royal Astronomical Society, 536(1), 387-407. https://doi.org/10.1093/mnras/stae2581

Journal Article Type Article
Acceptance Date Nov 13, 2024
Online Publication Date Nov 15, 2024
Publication Date Jan 1, 2025
Deposit Date Nov 15, 2024
Publicly Available Date Dec 9, 2024
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 536
Issue 1
Pages 387-407
DOI https://doi.org/10.1093/mnras/stae2581
Keywords Catalogues; Galaxies: evolution; Galaxies: nuclei; Radio continuum: galaxies; Radio lines: galaxies; Ultraviolet: galaxies
Public URL https://hull-repository.worktribe.com/output/4919069

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0

Copyright Statement
© 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.





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