Direct Evidence for Outflow Driven by Wolf-Rayet Stars in the Nearby Galaxy PGC44685

Abstract

Wolf--Rayet (WR) stars are evolved massive stars which can drive strong stellar winds, injecting energy and momentum into the interstellar medium (ISM). However, the geometry and kinematics of WR-dominated outflows, specially in low-metallicity environments, is still poorly constrained by observations. We present a spatially resolved spectroscopic study of a WR region in a nearby dwarf galaxy, PGC\,44685, using high-resolution MEGARA IFU data from the Gran Telescopio Canarias (GTC). After decomposing the [\textsc{O iii}]~$\lambda5007$ emission line with narrow and broad components, we verify a WR-driven outflow with a velocity reaching up to $20\,\mathrm{km\,s^{-1}}$ relative to the systemic velocity. By use of the velocity and flux of the [\textsc{O iii}] broad component, we estimate an outflow mass of $(8.25 \pm 3.03)\times10^{3}\,M_\odot$ and a mass-loss rate of $(9.47 \pm 3.48)\times10^{-4}\,M_\odot\,\mathrm{yr}^{-1}$. The corresponding kinetic power and momentum injection rate are $(4.77 \pm 1.77)\times10^{41}\,\mathrm{erg\,s^{-1}}$ and $(8.20 \pm 3.02)\times10^{28}\,\mathrm{g\,cm\,s^{-2}}$, respectively. The inferred low energy-loading efficiency ($\sim0.35\%$), together with the low metallicity of the WR region ($\sim0.1\,Z_\odot$), suggests that the system is observed in an early feedback phase in which stellar winds have not yet efficiently coupled their energy into the ISM. These results support the ability of WR feedback to shape the ISM on sub-kiloparsec scales, while these winds fail to launch galactic-scale outflows.