The Velocity Map Asymmetry of Ionized Gas in MaNGA. I. The Catalog and General Properties

TL;DR

This study presents a catalog of ionized gas velocity asymmetries in 5353 MaNGA galaxies, revealing correlations with galaxy type, stellar mass, and observational factors, enhancing understanding of galaxy kinematics.

Contribution

It provides the first large-scale catalog of kinematic asymmetries in ionized gas for MaNGA galaxies and analyzes their correlations with galaxy properties and observational effects.

Findings

Special galaxies have more high asymmetry cases.

High asymmetry is common even in regular galaxies.

Asymmetry anti-correlates with stellar mass below 10^9.7 M_sun.

Abstract

The SDSS-IV MaNGA survey has measured two-dimensional maps of emission line velocities for a statistically powerful sample of nearby galaxies. The asymmetric features of these kinematics maps reflect the non-rotational component of a galaxy's internal motion of ionized gas. In this study, we present a catalog of kinematic asymmetry measurement of $H\alpha$ velocity map of a sample of 5353 MaNGA galaxies. Based on this catalog, we find that `special' galaxies (e.g. merging galaxies, barred galaxies, and AGN host galaxies) contain more galaxies with highly asymmetric velocity maps. However, we notice that more than half of galaxies with high kinematic asymmetry in our sample are quite `regular'. For those `regular' galaxies, kinematic asymmetry shows a significant anti-correlation with stellar mass at $\log M_\star < 9.7$, while such a trend becomes very weak at $\log M_\star>9.7$. Moreover, at a given stellar mass, the kinematic asymmetry shows weak correlations with photometric morphology, star formation rate, and environment, while it is independent of HI gas content. We also have quantified the observational effects in the kinematic asymmetry measurement. We find that both the signal-to-noise ratio of $H\alpha$ flux and disk inclination angle contribute to the measures of kinematic asymmetry, while the physical spatial resolution is an irrelevant factor inside the MaNGA redshift coverage.