Internal Kinematics of UM 461 and CTS 1020

TL;DR

This study uses integral field spectroscopy to analyze the internal kinematics of two H II galaxies, revealing different motion patterns, the influence of stellar feedback, and possible star formation scenarios.

Contribution

It provides detailed kinematic maps and analysis of UM 461 and CTS 1020, highlighting their distinct dynamical behaviors and feedback effects, which were not previously characterized in such detail.

Findings

UM 461 shows weak kinematic connection between knots

CTS 1020 exhibits ordered rotation with a disturbed velocity field

UM 461's outer regions are dominated by diffuse gas

Abstract

We have used integral field spectroscopy to study the internal kinematics of the H\,{\sc ii} galaxies CTS 1020 and UM 461. We based our analysis on the velocity and velocity dispersion maps, and intensity-velocity dispersion ($I-\sigma$) and velocity-velocity dispersion ($V_r-\sigma$) diagrams. We found that the motion in both star-forming knots of UM 461 has different patterns, suggesting a weak kinematical connection between the knots. The overall kinematics of the galaxy is probably affected by stellar feedback. CTS 1020 has an ordered motion with a gradient compatible with a disc rotating at $\sim50$ km s$^{-1}$, though the velocity field is disturbed. In both galaxies the highest and lowest $\sigma$ values are distributed in the outer parts and are associated with the diffuse gas that permeates the galaxies. UM 461 has a ring-like structure with small regions of increasing $\sigma$ in the eastern knot, which resemble what we could expect in a collect and collapse scenario of star formation. We found that UM 461 seems to be more susceptible to stellar feedback, whereas in CTS 1020 the gravitational potential dominates.