WALLABY pilot survey: Properties of H <scp>i</scp>-selected dark sources and low surface brightness galaxies

Abstract We examine the optical counterparts of the 1 829 neutral hydrogen (H i ) detections in three pilot fields in the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) using data from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys DR10. We find that 17% (315) of the detections are optically low surface brightness galaxies (LSBGs; mean g -band surface brightness within 1 $ R_e$ of $\gt 23$ mag arcsec $^{-2}$ ) and 3% (55) are optically ‘dark’. We find that the gas-rich WALLABY LSBGs have low star formation efficiencies, and have stellar masses spanning five orders of magnitude, which highlights the diversity of properties across our sample. 75% of the LSBGs and all of the dark H i sources had not been catalogued prior to WALLABY. We examine the optically dark sample of the WALLABY pilot survey to verify the fidelity of the catalogue and investigate the implications for the full survey for identifying dark H i sources. We assess the H i detections without optical counterparts and identify 38 which pass further reliability tests. Of these, we find that 13 show signatures of tidal interactions. The remaining 25 detections have no obvious tidal origin, so are candidates for isolated galaxies with high H i masses, but low stellar masses and star-formation rates. Deeper H i and optical follow-up observations are required to verify the true nature of these dark sources.

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Publication Details

Journal
Publications of the Astronomical Society of Australia
Published
2025-01-01
DOI
https://doi.org/10.1017/pasa.2025.10047
Citations
4
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
4.77
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article

WALLABY pilot survey: Properties of H i-selected dark sources and low surface brightness galaxies

Nathan Deg, T. Westmeier, Edward N. Taylor, J. Rhee et al.
4 citations
Publications of the Astronomical Society of Australia
Astronomy and Astrophysical Research
4.77
article

WALLABY pilot survey: Properties of H i-selected dark sources and low surface brightness galaxies

Nathan Deg, T. Westmeier, Edward N. Taylor, J. Rhee, V. A. Kilborn, Bi‐Qing For, T. O’Beirne, L. Staveley‐Smith, M. E. Cluver, C. Murugeshan, Kenji Bekki, K. Lee-Waddell, Kyle A. Oman, Helga Dénes, O. Ivy Wong, Austin Shen
article en
4 citations

Abstract

Abstract We examine the optical counterparts of the 1 829 neutral hydrogen (H i ) detections in three pilot fields in the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) using data from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys DR10. We find that 17% (315) of the detections are optically low surface brightness galaxies (LSBGs; mean g -band surface brightness within 1 $ R_e$ of $\gt 23$ mag arcsec $^{-2}$ ) and 3% (55) are optically ‘dark’. We find that the gas-rich WALLABY LSBGs have low star formation efficiencies, and have stellar masses spanning five orders of magnitude, which highlights the diversity of properties across our sample. 75% of the LSBGs and all of the dark H i sources had not been catalogued prior to WALLABY. We examine the optically dark sample of the WALLABY pilot survey to verify the fidelity of the catalogue and investigate the implications for the full survey for identifying dark H i sources. We assess the H i detections without optical counterparts and identify 38 which pass further reliability tests. Of these, we find that 13 show signatures of tidal interactions. The remaining 25 detections have no obvious tidal origin, so are candidates for isolated galaxies with high H i masses, but low stellar masses and star-formation rates. Deeper H i and optical follow-up observations are required to verify the true nature of these dark sources.

Publications of the Astronomical Society of AustraliaVol. 42
Commonwealth Scientific and Industrial Research Organisation (AU), The University of Western Australia (AU), Durham University (GB), Queen's University (CA), Curtin University (AU), Universidad Yachay Tech (EC), ASTRO-3D (AU), Astronomy and Space (AU), ARC Centre of Excellence for All-sky Astrophysics (AU), International Centre for Radio Astronomy Research (AU), Abiola Ajimobi Technical University Ibadan (NG), Swinburne University of Technology (AU)
Openalex Percentile: Top 5%
Astronomy and Astrophysical Research
4.77
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