AGN-Driven Outflows in Dwarf Galaxies

We present spatially resolved kinematic measurements of active galactic nucleus (AGN)-driven outflows in dwarf galaxies in the stellar mass range ∼6 × 10⁸-9 × 10⁹ M _⊙, selected from SDSS DR7 and DR8 and followed-up with Keck/LRIS spectroscopy. We find spatially extended (∼1 half-light radius), high-velocity ionized gas outflows (W ₈₀ up to ∼2000 km s^-1) in 13/50 dwarf galaxies with and without an AGN. Outflow velocities in all 13 galaxies exceed the escape velocities of their halos. Nine of these 13 galaxies are classified as AGNs according to their narrow line flux ratios. Of these, six have outflow components with emission-line ratios consistent with AGN ionization. Although black holes (BHs) have been known to populate the centers of at least a few dwarf galaxies and indirect evidence of AGN quenching of star formation in dwarfs has begun to surface, our measurements constitute the first direct detection and measurement of AGN impact on the large-scale kinematics and gas content in dwarf galaxies. Furthermore, we find evidence suggestive of ongoing star formation suppression, possibly regulated by the AGN. Galaxy formation models must therefore be able to account not only for the formation and growth of BHs at the centers of dwarf galaxies, but should also be revised to include AGNs as important—and perhaps dominant—sources of feedback in low-mass galaxies.