Determining the Timescale over Which Stellar Feedback Drives Turbulence in the Interstellar Medium: A Study of Four Nearby Dwarf Irregular Galaxies
Abstract
Stellar feedback is fundamental to the modeling of galaxy evolution, as it drives turbulence and outflows in galaxies. Understanding the timescales involved are critical for constraining the impact of stellar feedback on the interstellar medium. We analyzed the resolved star formation histories along with the spatial distribution and kinematics of the atomic and ionized gas of four nearby star-forming dwarf galaxies (NGC 4068, NGC 4163, NGC 6789, and UGC 9128) to determine the timescales over which stellar feedback drives turbulence. The four galaxies are within 5 Mpc and have a range of properties inlcuding current star formation rates of 0.0005-0.01 $M_\odot$ yr$^{-1}$, $\log(M_\ast/M_\odot)$ between 7.2 and 8.2, and $\log(M_{\mathrm{HI}}/M_\odot)$ between 7.2 and 8.3. Their color-magnitude diagram derived star formation histories over the past 500 Myr were compared to their atomic and ionized gas velocity dispersion and HI energy surface densities as indicators of turbulence. The Spearmans rank correlation coefficient was used to identify any correlations between their current turbulence and their past star formation activity on local scales (~400 pc). The strongest correlation was found between the HI turbulence measures and the star formation rate 100-200 Myr ago. This suggests a coupling between the star formation activity and atomic gas on this timescale. No strong correlation between the ionized gas velocity dispersion and the star formation activity between 5 and 500 Myr ago was found. The sample and analysis are the foundation of a larger program aimed as understanding the timescales over which stellar feedback drives turbulence.
Ray Garner
TAMU Astronomy Postdoctoral Researcher
I’m a scientist, Star Wars fan, and amateur photographer raised in Georgia. My research interests include galaxy evolution, star formation, satellite galaxies, and nebular diagnostics.