Stellar feedback impact on the ionized gas kinematics in the dwarf galaxy Sextans A

TL;DR

This study investigates how stellar feedback influences the ionized gas kinematics in the low-metallicity dwarf galaxy Sextans A, revealing multiple superbubbles and outflows driven by massive stars, contrasting with atomic hydrogen rotation.

Contribution

It provides the first detailed analysis of ionized gas kinematics and feedback effects in Sextans A, highlighting the role of supernova remnants and stellar outflows in shaping the ISM.

Findings

Identified 10 expanding superbubbles aged 1-3 Myr.

Detected outflows in star-forming regions via gas kinematics.

Ionized gas kinematics are dominated by stellar feedback, not rotation.

Abstract

Feedback from massive stars shapes the ISM and affects the evolution of galaxies, but its mechanisms acting at the small scales ($\sim 10$ pc) are still not well constrained observationally, especially in the low-metallicity environments. We present the analysis of the ionized gas (focusing on its kinematics, which were never studied before), and its connection to the massive stars in the nearby ($D \sim 1.4$ Mpc) star-forming very metal-poor ($Z\sim 0.07 Z_\odot$) galaxy Sextans A. The analysis is based on the observations with a scanning Fabry-Perot interferometer, long-slit spectroscopy and imaging in emission lines with narrow-band tunable filters. We found 10 expanding superbubbles of ionized gas with ages of 1-3 Myr. We argue that 3 of them are probable supernovae remnants, while the pre-supernovae feedback is an important source of energy for blowing-out the remaining superbubbles. The two brightest sites of star formation exhibit signs of outflowing ionized gas, which is traced by its ionized and atomic gas kinematics and (in one case) by its emission line flux ratios. Overall, the ionized gas kinematics in Sextans A is highly affected by the feedback from several generations of massive stars and inconsistent with the mere solid-body rotation observed in atomic hydrogen.