Two types of distribution of the gas velocity dispersion of MaNGA galaxies

Abstract

The distribution of the gas velocity dispersion sigma across the images of 1146 MaNGA galaxies is analyzed. We find that there are two types of distribution of the gas velocity dispersion across the images of galaxies: (i) the distributions of 909 galaxies show a radial symmetry with or without the sigma enhancement at the center ("R distribution", radial symmetry in the sigma distribution) and (ii) distributions with a band of enhanced sigma along the minor axis in the images of 159 galaxies with or without the sigma enhancement at the center ("B distribution", band in the sigma distribution). The sigma distribution across the images of 78 galaxies cannot be reliable classified. We select 806 galaxies with the best defined characteristics (this sample includes 687 galaxies with R distribution and 119 galaxies with B distribution) and compare the properties of galaxies with R and B distributions. We find that the median value of the gas velocity dispersion sigma (m) in galaxies with B distribution is higher by around 5 km s(-1), on average, than that of galaxies with R distribution. The optical radius R-25 of galaxies with B distribution is lower by around 0.1 dex, on average, than that of galaxies with similar masses with R distribution. Thus the properties of a galaxy are related to the type of distribution of the gas velocity dispersion sigma across its image. This suggests that the presence of the band of the enhanced gas velocity dispersion can be an indicator of a specific evolution (or a specific stage in the evolution) of a galaxy. © ESO 2021.