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

TL;DR

This study analyzes the distribution patterns of gas velocity dispersion in 1146 MaNGA galaxies, identifying two main types and linking these patterns to galaxy properties and evolutionary stages.

Contribution

It classifies the gas velocity dispersion distributions into two types and correlates these with galaxy properties, offering insights into galaxy evolution stages.

Findings

B distribution galaxies have higher median gas velocity dispersion.

R distribution galaxies have larger optical radii.

Distribution type correlates with galaxy evolutionary stage.

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) 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) 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, 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 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.