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

Feedback from massive stars shapes the interstellar medium (ISM) and affects the evolution of galaxies, but its mechanisms acting at the small scales (similar to 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 similar to 1.4 Mpc) star-forming very metal poor (Z similar to 0.07 Z(circle dot)) 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 three of them are probable supernova remnants, while the pre-supernova 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.

Automated summary

Feedback from massive stars has significant impacts on the interstellar medium and galaxy evolution. However, the mechanisms of feedback at small scales, especially in low-metallicity environments, remain poorly understood observationally. This study analyzes the ionized gas in the nearby star-forming galaxy Sextans A and its connection to massive stars. The results reveal expanding superbubbles of ionized gas and provide evidence of feedback from supernovae and the pre-supernova phase.