HI asymmetries of galaxies in the Ursa Major and Perseus-Pisces environments

TL;DR

This study compares atomic Hydrogen (HI) asymmetries in galaxies within the Ursa Major group and Perseus-Pisces filament, revealing environmental influences on galaxy morphology and kinematics through HI observations.

Contribution

It provides a comparative analysis of HI asymmetries in different cosmic environments using homogenized radio data and introduces criteria for measuring asymmetries in galaxy HI profiles.

Findings

Higher fraction of asymmetric HI profiles in Perseus-Pisces (33%) than Ursa Major (9%)

More morphological HI asymmetries detected in Perseus-Pisces (46%) versus Ursa Major (13%)

Uncorrelated stellar and HI morphological asymmetries in both environments

Abstract

The morphology and kinematics of atomic Hydrogen (HI) gas in galaxies are influenced by both local and large scale cosmic environments. Differences in galaxy environment and interactions can leave distinct signatures in HI asymmetry, offering insight into environmental effects on galaxy evolution. We investigate the role of environment on HI asymmetries in galaxies located in two contrasting structures: the Ursa Major (UMa) group and the Perseus Pisces (PP) filament. We analyze HI 21cm imaging from the WSRT and the VLA, homogenized in resolution for fair comparison. Asymmetries in global profiles and column density maps are measured using criteria established in arXiv:2205.00675 and compared to those of mock galaxies presented in the same study. The PP volume hosts a higher fraction of galaxies with asymmetric global HI profiles (33%) compared to UMa (9%). Likewise, 46% of PP galaxies have morphological HI asymmetries above 0.5 at a threshold of 15 x 10^19 cm^-2, compared to 13% in UMa. The greater column density sensitivity of the UMa data enables detection of lopsided features and asymmetry measurement down to 5 x 10^19 cm^-2. We also identify simulated galaxies with unphysical asymmetries likely caused by unrealistic feedback. In both volumes, stellar and HI morphological asymmetries are uncorrelated. Global profile and morphological asymmetries are also found to be uncorrelated, consistent with previous results.