The Compact, Conical, Accretion‐Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and Its Implications for IGM‐Galaxy Feedback Processes

Abstract

Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains all the main physical and geometrical properties of an AGN ''warm absorber'' wind. The absorber consists of two different ionization components, with a difference of %100 in ionization parameter and %5 in column density. By tracking the response in the opacity of the gas to changes in the ionizing continuum, we were able to constrain the electron density of the system. We find n e ¼ (5:8Y21:0) ; 10 6 cm À3 for the high-ionization absorber and n e > 8:1 ; 10 7 cm À3 for the low-ionization absorber. These densities require that the high-and low-ionization absorbing components of NGC 4051 must be compact, at distances 0.5Y1.0 lt-days (2200R S Y4400R S ) and <3.5 lt-days (<15;800R S ) from the continuum source, respectively. This rules out an origin in the dusty obscuring torus, as the dust sublimation radius is at least an order of magnitude larger ($12 lt-days). An accretion-disk origin for the warm absorber wind is strongly suggested, and an association with the high-ionization, He ii emitting, broad emission line region (radius <2 lt-days) is possible. The two detected phases are consistent with pressure equilibrium, which suggests that the absorber consists of a two-phase medium. A radial flow in a spherical geometry is unlikely, and a conical wind geometry is preferred. The implied mass outflow rate from this wind can be well constrained and is 2%Y5% of the mass accretion rate. If the mass outflow rate scaling with accretion rate is representative of all quasars, our results imply that warm absorbers in powerful quasars are unlikely to produce important evolutionary effects on their larger environment, unless we are observing the winds before they get fully accelerated. Only in such a scenario can AGN winds be important for cosmic feedback.

The XMM deep survey in the CDF-S

“…In the following calculations, we adopt the "prescriptions" of Tombesi et al (2012a) and Crenshaw & Kraemer (2012); see also Krongold et al (2007) and Pounds & Reeves (2009) for additional discussion of outflows and related geometry.…”

X-ray evidence for a mildly relativistic and variable outflow in the luminous Seyfert 1 galaxy Mrk 509

“…Variability studies could, in principle, allow us to estimate the location and geometry of the absorber (Nicastro et al 1999;Krongold et al 2007;Risaliti et al 2005;Reeves et al 2008), thereby placing more stringent limits on the remaining large (order of magnitude) uncertainties in the total mass, energy and momentum that is driven by these outflows (Elvis 2006).…”

Hubble Space Telescope observations of BALQSO Ton 34 reveal a connection between the broad-line region and the BAL outflow

“…Such wind would be ubiquitous in AGN but only visible when the gas crosses our line of sight (Goodrich & Miller 1995;Hines & Wills 1995;Murray et al 1995;Elvis 2000;. It has also been suggested that the same gas may be responsible for absorption and emission (e.g., Mathur et al 1995;Elvis 2000;Fields et al 2005;Krongold et al 2007;Andrade-Velazquez et al 2010;Longinotti et al 2013;Miniutti et al 2014;Sanfrutos et al 2016), or that BALs may be associated to the obscuring dusty torus (Leighly et al 2015). However, other scenarios suggest that the incidence of BALs may be related to evolutionary phases (Hazard et al 1984;Becker et al 2000) and that mini-BALs and BALs may represent the same outflow but at different evolutionary stages (Hamann & Sabra 2004).…”