WALLABY Pilot Survey: Characterizing Low-rotation Kinematically Modeled Galaxies

Abstract Many of the tensions in cosmological models of the Universe lie in the low-mass, low-velocity regime. Probing this regime requires a statistically significant sample of galaxies with well-measured kinematics and robustly measured uncertainties. The Widefield ASKAP L -band Legacy All-sky Blind surveY (WALLABY), as a wide-area, untargeted H i survey, is well positioned to construct this sample. As a first step toward this goal, we develop a framework for testing kinematic modeling codes in the low-resolution, low signal-to-noise ratio, low rotation velocity regime. We find that the WALLABY Kinematic Analysis Proto-Pipeline is remarkably successful at modeling these galaxies when compared to other algorithms, but, even in idealized tests, there is a significant fraction of false positives found below inclinations of ≈40°. We further examine the 11 detections with rotation velocities below 50 km s −1 in the WALLABY pilot data releases. We find that those galaxies with inclinations above 40° lie within 1 σ –2 σ of structural scaling relations that require reliable rotation velocity measurements, such as the baryonic Tully–Fisher relation. Moreover, the subset that has consistent kinematic and photometric inclinations tends to lie nearer to the relations than those that have inconsistent inclination measures. This work both demonstrates the challenges faced in low-velocity kinematic modeling and provides a framework for testing modeling codes as well as constructing a large sample of well-measured low-rotation models from untargeted surveys.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-11-27
DOI
https://doi.org/10.3847/1538-4357/ae1003
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
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article

WALLABY Pilot Survey: Characterizing Low-rotation Kinematically Modeled Galaxies

Nathan Deg, T. Westmeier, Nikhil Arora, Jonghwan Rhee et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

WALLABY Pilot Survey: Characterizing Low-rotation Kinematically Modeled Galaxies

Nathan Deg, T. Westmeier, Nikhil Arora, Jonghwan Rhee, V. A. Kilborn, L. Cortese, Barbara Catinella, Bi‐Qing For, H. Peter White, T. O’Beirne, Lister Staveley‐Smith, Kristine Spekkens, Ao Shen, Mark L. A. Richardson, K. Lee-Waddell, Adrien Hélias, Helga Dénes, Li Shao, Gilles Ferrand, O. Ivy Wong, Ahmed Elagali, Jayanne English, R. M. Dudley
article en

Abstract

Abstract Many of the tensions in cosmological models of the Universe lie in the low-mass, low-velocity regime. Probing this regime requires a statistically significant sample of galaxies with well-measured kinematics and robustly measured uncertainties. The Widefield ASKAP L -band Legacy All-sky Blind surveY (WALLABY), as a wide-area, untargeted H i survey, is well positioned to construct this sample. As a first step toward this goal, we develop a framework for testing kinematic modeling codes in the low-resolution, low signal-to-noise ratio, low rotation velocity regime. We find that the WALLABY Kinematic Analysis Proto-Pipeline is remarkably successful at modeling these galaxies when compared to other algorithms, but, even in idealized tests, there is a significant fraction of false positives found below inclinations of ≈40°. We further examine the 11 detections with rotation velocities below 50 km s −1 in the WALLABY pilot data releases. We find that those galaxies with inclinations above 40° lie within 1 σ –2 σ of structural scaling relations that require reliable rotation velocity measurements, such as the baryonic Tully–Fisher relation. Moreover, the subset that has consistent kinematic and photometric inclinations tends to lie nearer to the relations than those that have inconsistent inclination measures. This work both demonstrates the challenges faced in low-velocity kinematic modeling and provides a framework for testing modeling codes as well as constructing a large sample of well-measured low-rotation models from untargeted surveys.

The Astrophysical JournalVol. 994(2)
Western University (CA), Commonwealth Scientific and Industrial Research Organisation (AU), The University of Western Australia (AU), University of Toronto (CA), Chinese Academy of Sciences (CN), Queen's University (CA), Universidad Yachay Tech (EC), ASTRO-3D (AU), Arthur B. McDonald-Canadian Astroparticle Physics Research Institute (CA), RIKEN (JP), Astronomy and Space (AU), ARC Centre of Excellence for All-sky Astrophysics (AU), International Centre for Radio Astronomy Research (AU), National Astronomical Observatories (CN), University of Manitoba (CA), Swinburne University of Technology (AU)
Openalex Percentile: Top 75%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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