Quantifying the energy balance between massive stars and ISM with MUSE and HST

Massive stars in star-forming regions inject huge amounts of energy and momentum into the ISM producing ubiquitous superbubbles, turbulent gas motions and outflows. The coupling efficiency of mechanical stellar feedback and its dependence on metallicity remains uncertain in simulations. The high angular and sufficient spectral resolution of MUSE allow one to characterize the small-scale (50-500 pc) ionized gas kinematics and quantify the energetics of the ISM. From the MUSE data, we identified about 1500 expanding superbubbles and regions with significant turbulent gas motions in 19 nearby star-forming galaxies from the PHANGS survey. Using the HST multi-wavelength observations, we linked these regions with the massive star clusters and measured the coupling efficiency of mechanical stellar feedback, directly from the observations. We found that the small-scale dynamics in the identified regions are mostly regulated by massive stars, with significant contribution of pre-SN feedback. The measured kinetic energy of the small-scale gas motions declines in the low-metallicity environment. Overall, our results demonstrate a synergy between the MUSE and space-based observatories like HST in quantifying the energy balance between the stars and gas in the nearby galaxies.