Warm absorbers and outflows in the Seyfert-1 galaxy NGC 4051

Abstract

We present both phenomenological and more physical photoionization models of the Chandra/HETG spectra of the Seyfert-1 active galactic nucleus NGC4051. We detect 40 absorption and emission lines, encompassing highly ionized charge states from O, Ne, Mg, Si, S, and the Fe L-shell and K-shell. Two independent photoionization packages, XSTAR and Cloudy, were both used to self-consistently model the continuum and line spectra. These fits detected three absorbing regions in this system with densities ranging from 1010 to 10 11cm-3. In particular, our XSTAR models require three components that have ionization parameters of log (ξ) = 4.5, 3.3, and 1.0, and are located within the broad-line region at 70, 300, and 13000Rg , respectively, assuming a constant wind density. Larger radii are inferred for density profiles which decline with radius. The Cloudy models give a similar set of parameters with ionization parameters of log (ξ) = 5.0, 3.6, and 2.2 located at 40, 200, and 3300Rg . We demonstrate that these regions are outflowing from the system, and carry a small fraction of material out of the system relative to the implied mass accretion rate. The data suggest that magnetic fields may be an important driving mechanism. © 2012. The American Astronomical Society. All rights reserved..