VALES VIII: Weak ionized gas outflows in star-forming galaxies at $z \sim 0.15$ traced with VLT/MUSE

Abstract

We characterize the ionized gas outflows in 15 low-redshift star-forming galaxies, a Valpara\'iso ALMA Line Emission Survey (VALES) subsample, using MUSE integral field spectroscopy and GAMA photometric broadband data. We measure the emission-line spectra by fitting a double-component profile, with the second and broader component being related to the outflowing gas. This interpretation is in agreement with the correlation between the observed star-formation rate surface density ($\Sigma_{\mathrm{SFR}}$) and the second-component velocity dispersion ($\sigma_{\mathrm{2nd}}$), expected when tracing the feedback component. By modelling the broadband spectra with spectra energy distribution (SED) fitting and obtaining the star-formation histories of the sample, we observe a small decrease in SFR between 100 and 10 Myr in galaxies when the outflow H$\alpha$ luminosity contribution is increased, indicating that the feedback somewhat inhibits the star formation within these timescales. The observed emission-line ratios are best reproduced by photoionization models when compared to shock-ionization, indicating that radiation from young stellar population is dominant, and seems to be a consequence of a continuous star-formation activity instead of a bursty event. The outflow properties such as mass outflow rate ($\sim 0.1\,$M$_\odot$ yr$^{-1}$), outflow kinetic power ($\sim 5.2 \times 10^{-4}\% L_{\mathrm{bol}}$) and mass loading factor ($\sim 0.12$) point towards a scenario where the measured feedback is not strong and has a low impact on the evolution of galaxies in general.