The GMRT archive atomic gas survey – IV. Consistency of the dark matter halo perturbation parameter from morphological and kinematic lopsidedness of galaxies

Abstract

The lopsidedness of galaxies is a commonly observed phenomenon, and through different studies, it has been observed that nearly 30 % of galaxies show this phenomenon. In this work, we study morphological lopsidedness in both stellar and gas discs in the inner and outer regions using Fourier analysis techniques and compare the results for a sample of nearby galaxies with different morphologies and environments. Although lopsidedness can result from diverse factors like tidal interactions, gas accretion, and internal instability, recent studies suggest it is a common feature that is not solely reliant on rare events, and moderate lopsidedness most likely results from the disc’s response to a lopsided dark matter halo potential. Assuming lopsidedness originates due to a lopsided halo, we find the morphological and kinematic halo perturbation parameters in the same radial range. Unlike previous studies, we use 3D kinematic modelled rotation curves for finding kinematic lopsidedness and, hence, the kinematic halo perturbation parameter. Although the detected linear correlation between them is not statistically significant for our small sample of 11 galaxies, this approach provides a more uniform and physically consistent framework to test the theoretically expected similarity between morphological and kinematic halo perturbation parameters. Further, within this framework, the discrepancy between them does not appear to depend on the nature of the rotation curve asymmetry of the two sides of the galaxy, in contrast to trends seen in earlier studies. In future work, we plan to extend this analysis to a substantially larger sample in order to robustly assess these findings. © The Author(s) 2026. 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.