EMPRESS. VI. Outflows Investigated in Low-mass Galaxies with M _∗ = 10⁴–10⁷ M _⊙: Weak Feedback in Low-mass Galaxies?

We study emission line profiles of 21 nearby low-mass ($M_*=10^4-10^7~M_\odot$) galaxies in deep medium-high resolution spectra taken with Magellan/MagE. These are actively star-forming systems high specific star-formation rates $\mathrm{sSFR}\sim100-1000~\mathrm{Gyr}^{-1}$ that well above the main sequence and its extrapolation. identify broad-line components H$\alpha$ [OIII]$\lambda 5007$ 14 out cannot be explained by MagE instrumental profile or natural broadening emission. conduct double Gaussian fitting to galaxies, find have widths significantly larger than those narrow-line components, indicative galactic outflows. The board-line moderately large $\sim 100$ km s$^{-1}$. estimate maximum outflow velocities $v_\mathrm{max}$ obtain values $\simeq 60-200$ s$^{-1}$, which found comparable slightly escape velocities. Positive correlations rates, stellar masses, circular velocities, extend down into this regime. Broad- flux ratios BNRs generally smaller massive galaxies. small suggest mass loading factors $\eta$ can as 0.1 - 1 below, contrast energy-driven outflows predicted numerical simulations.