An escaping outflow in a galaxy with an intermediate-mass black hole

Abstract

While in massive galaxies active galactic nucleus (AGN) feedback plays an important role, the role of AGN feedback is still under debate in dwarf galaxies. With well spatially resolved data obtained from the Multi-Unit Spectroscopic Explorer, we identify a spatially extended (∼3 kpc) and fast (V80 ∼471 km s-1) AGN-driven outflow in a dwarf galaxy: Sloan Digital Sky Survey J022849.51-090153.8 with M∗∼109.6 M⊙ that host an intermediate-mass black hole of M BH ∼105 M⊙ and LAGN/LEdd ∼0.15. Through the measurement of the rotation curve, we estimate the escape velocity of the halo and the ratio of the outflow velocity to the halo escape velocity to be 1.09 ± 0.04, indicating that the outflow is capable of escaping not only the galaxy disc but the halo. The outflow size of our AGN is found to be larger than AGN in massive galaxies at the given AGN [O iii] luminosity, while the size of the photoionized narrow-line region is comparable. These results suggest the important role of AGN feedback through outflows in dwarf galaxies when their central intermediate-mass black holes accrete at high-Eddington ratios.