WALLABY Pilot Survey: KNN identification of perturbed galaxies through H i morphometrics
Journal article, 2025
Galaxy morphology in stellar light can be described by a series of "non-parametric"or "morphometric"parameters, such as concentrationasymmetry-smoothness, Gini, M20, and Sersic fit. These parameters can be applied to column density maps of atomic hydrogen (Hi). The Hi distribution is susceptible to perturbations by environmental effects, e.g. inter-galactic medium pressure and tidal interactions. Therefore, Hi morphology can potentially identify galaxies undergoing ram-pressure stripping or tidal interactions. We explore three fields in theWALLABY Pilot Hi survey and identify perturbed galaxies based on a k-nearest Neighbor (kNN) algorithm using an Hi morphometric feature space. For training, we used labeled galaxies in the combined NGC 4808 and NGC 4636 fields with six Hi morphometrics to train and test a kNN classifier. The kNN classification is proficient in classifying perturbed galaxies with all metrics -accuracy, precision and recall- at 70-80%. By using the kNN method to identify perturbed galaxies in the deployment field, the NGC 5044 mosaic, we find that in most regards, the scaling relations of perturbed and unperturbed galaxies have similar distribution in the scaling relations of stellar mass vs star formation rate and the Baryonic Tully-Fisher relation, but the Hi and stellar mass relation flatter than of the unperturbed galaxies. Our results for NGC 5044 provide a prediction for future studies on the fraction of galaxies undergoing interaction in this catalogue and to build a training sample to classify such galaxies in the fullWALLABY survey.
Galaxies galaxies: structure
galaxies: evolution
Galaxies galaxies: ISM
Galaxies
Galaxies galaxies: interactions
Author
B. W. Holwerda
University of Louisville
H. Dénes
Yachay Tech University
Jonghwan Rhee
University of Western Australia
Denis Leahy
University of Calgary
B. Koribalski
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Western Sydney University
Niankun Yu
Chinese Academy of Sciences
Nathan Deg
Queen's University
T. Westmeier
University of Western Australia
Karen Lee-Wadde
Universidad Autonoma de Madrid (UAM)
Australian SKA Regional Centre (AusSRC)
Yago Ascasibar
Universidad Autonoma de Madrid (UAM)
Manasvee Saraf
ARC Centre of Excellence for All-sky Astrophysics
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
University of Western Australia
Xuchen Lin
Beijing University of Technology
B. Catinella
University of Western Australia
ARC Centre of Excellence for All-sky Astrophysics
Kelley Michelle Hess
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Publications Astronomical Society of Australia
1323-3580 (ISSN) 1448-6083 (eISSN)
Vol. 42 e028Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1017/pasa.2025.5