Numerical Simulation of X-Ray--heated Winds in Seyfert Galaxies. I. The Case of Zero Angular Momentum
Abstract
We numerically simulate the structure of the X-ray heated winds believed to form the "mirrors" which reflect light from obscured Seyfert galaxy nuclei into our line of sight. The order of magnitude estimates made by Krolik & Begelman are largely confirmed. For a central luminosity of 10^44^ ergs s^-1^ and an inner toroidal radius of 1 pc, the characteristic temperature in the wind is ~1 X 10^6^ K, and the flow speed is several hundred km s^-1^. When L/L_E_ <~ 0.08, most of the mass evaporated off the torus's inner edge is captured; when L/L_E_ > 0.08, a substantial wind is driven off, with a maximum mass-loss rate that scales roughly in proportion to the injection pressure. Even when L/L_E_ > 0.08, if mass is injected more rapidly than the maximum rate, it is captured. Subsonic, or at most weakly supersonic, injection is necessary in order for most of the mass injected to be expelled. We present predictions of: the reflected fraction, the polarization of reflected light, the mean frequency shift and broadening of reflected line features, the equivalent width of X-ray lines from Fe^+20^ and Fe^+25^, and the soft X-ray luminosity of the wind. All these quantities vary significantly with viewing angle. The reflected fraction and the soft X-ray luminosity vary particularly strongly, rising quasi-exponentially as our view changes from equatorial to just barely obscured. Comparison with data from NGC 1068 (Miller, Goodrich, & Mathews) suggests that we may be viewing this object close to the plane of the torus, and the scale of the mirror may be as large as ~ 50(h/0.5)^-2^ pc. Subject headings cooling flows - galaxies: Seyfert - X-rays: galaxies
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1993
- DOI:
- 10.1086/172116
- Bibcode:
- 1993ApJ...402..109B
- Keywords:
-
- Angular Momentum;
- Cooling Flows (Astrophysics);
- Digital Simulation;
- Hydrodynamic Equations;
- Seyfert Galaxies;
- X Ray Astronomy;
- Active Galactic Nuclei;
- Boundary Conditions;
- Line Spectra;
- Stellar Winds;
- Astrophysics;
- GALAXIES: COOLING FLOWS;
- GALAXIES: SEYFERT;
- X-RAYS: GALAXIES