Radiative Driving of the AGN Outflows in the Narrow-Line Seyfert 1\n Galaxy NGC 4051

Abstract

We explore the properties of ionized gas in the nuclear and circumnuclear\nenvironment of the narrow-line Seyfert 1 galaxy NGC 4051 using spectroscopic\nand imaging observations from the Hubble Space Telescope (HST) and Apache Point\nObservatory (APO)'s ARC 3.5m Telescope. We identify an unresolved\nmoderate-density intermediate width component and a high-density broad\ncomponent in the optical emission lines from the active nucleus, as well as\nspatially-resolved emission extending up to $\\sim$1 kpc in the AGN ionized\nnarrow-line region (NLR) and $\\sim$8 kpc in the stellar ionized host galaxy.\nThe HST narrow-band image reveals a distinct conical structure in [O III]\nemission towards the NE, and the ionized gas kinematics shows up to two\nblueshifted velocity components, indicating outflows along the edges of a cone.\nWe introduce an improved model of biconical outflow, with our line of sight\npassing through the wall of the cone, which suggests that the large number of\noutflowing UV absorbers seen in NGC 4051 are NLR clouds in absorption. Using\nthe de-projection factors from the biconical geometry, we measure true outflow\nvelocities up to 680 km s$^{-1}$ at a distance of $\\sim$350 pc, however, we do\nnot find any rotational signature inside a projected distance $\\leq$ 10''\n($\\sim$800 pc) from the nucleus. We compare the gas kinematics with analytical\nmodels based on a radiation-gravity formalism, which show that most of the\nobserved NLR outflows are launched within $\\sim$0.5 pc of the nucleus and can\ntravel up to $\\sim$1 kpc from this low-luminosity AGN.\n