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Mass Outflows from AGN in Emission and Absorption. Mike Crenshaw (Georgia State University) Steve Kraemer (Catholic University of America). NGC 4151. Six HST /STIS echelle observations (0.2'' x 0.2''): 1999 July - 2002 May Simultaneous HST, FUSE , and CXO observations in 2002 May.
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Mass Outflows from AGN in Emission and Absorption Mike Crenshaw (Georgia State University) Steve Kraemer (Catholic University of America) NGC 4151
Six HST/STIS echelle observations (0.2'' x 0.2''): 1999 July - 2002 May • Simultaneous HST, FUSE, and CXO observations in 2002 May NGC 4151: UV Light Curve IUE: black pluses HUT: red diamonds FOS: green triangles STIS: blue x’s
Absorption Components in STIS and FUSE Spectra • A, C, D+E, E are intrinsic; B is Galactic; F, F are host galaxy. • D+E (vr = -500 km s-1) responsible for bulk of UV and X-ray absorption.
So what are the intrinsic absorbers? • What is their origin? • Accretion-disk winds, evaporation from torus? • What are their dynamics? • Radiatively-driven, thermal wind, hydromagnetic flows? (see Crenshaw, Kraemer, & George, 2003, ARA&A, 41, 117 ) • What observational constraints are needed? • Physical conditions: U (ionization parameter), NH (column density), nH (number density), abundances, etc. • Kinematics: radial velocity (vr), FWHM, transverse velocity (vT) • Geometry: Global covering factor (Cg), LOS covering factor (Clos), distribution with respect to accretion disk axis (polar angle )? • Radial location (r), mass outflow rate • Are the absorbers seen in emission? Yes: Emission lines from the high-column absorber in NGC 4151 provide tight constraints on dynamical models of the mass outflow.
Absorption Variability in C IV Region (Kraemer et al. 2006, ApJ, in press, astro-ph/0608383) • D+E varies strongly in response to ionizing continuum changes. • D+E in 2002: a large amount of gas moved out of the LOS.
Absorption Variability in X-rays (Kraemer et al. 2005, ApJ, 633, 693) • X-ray absorption primarily due to D+E • D+E decreased in NH between 2000 and 2002 • Evidence for a more highly ionized component: X-high
Photoionization Models of High-Column Absorbers • Density (nH) from metastable C III radial distance of D+E is ~0.1 pc • D+Ed change in los covering factor vT ≈ 2100 km s-1 • Other constraints? Yes! D+Ea is seen in emission.
He II profile has two components (broad component not detected): narrow: 250 km s-1 FWHM, intermediate: 1170 km s-1 FWHM • Evidence for an intermediate line region (ILR) Emission-Line Profiles at Low Flux Levels
Emission-Line Profiles at Low Flux Levels C IV blue - narrow red - intermediate green - broad • D+E absorbs ILR and has same velocity extent self absorption? • Are we seeing the absorption in emission? D+Ea should dominate • D+Ea absorber models should match the observed ILR line ratios
Intermediate Components in Other Lines blue - narrow red - intermediate green - broad (Crenshaw & Kraemer, 2006, ApJ, submitted)
Reasonably good match, considering no fine-tuning of absorber models - N V underpredicted (similar to most of our NLR models) • Which value of NH is more appropriate globally? - look at the variability of C IV ILR Line Ratios and D+Ea Photoionization Models
Variability of C IV Emission Components • Both BLR and ILR respond positively to continuum changes • Size of ILR ≤ 140 light days (0.12 pc)
ILR C IV vs. Continuum Flux + Observed --- High-N Model … Low-N Model • High-N model is a better match globally • Scale factor for High-N model gives Cg = 0.4 (global covering factor)
Can we constrain the geometry of the ILR? • Kinematic studies show the NLR of NGC 4151 is roughly biconical with a half-opening angle of ~33 and an inclination of ~45(Das et al. 2005). • Previous photoionization studies showed the NLR is shielded by an absorber with U, NH similar to D+Ea/ILR (Alexander et al. 1999, Kraemer et al. 2000). • Thus, the ILR is concentrated in the polar direction and extends to ≥ 45 ( = 53 gives Cg = 0.4) NLR and host galaxy
Simple Geometric Model • r = 0.1 pc, = 45, vr = vlos = - 490 km s-1 • Assume v = 0, then v = vT = 2100 km s-1(vT = 10,000 km s-1 also shown) • Emission-line vr ≤ 1550 km s-1, close to observed HWZI (1400 km s-1)
Dynamical Considerations • Consider the high-column absorbers D+E and X-high: • Radiation pressure: • To be efficient FM > (Lbol/Ledd)-1 = 70 for NGC 4151 • From Cloudy models: FM (X-high) < 2, FM (D+Ea) < 40 • X-high is not radiatively driven and D+E is marginally susceptible • Thermal wind: • Radial distance at which gas can escape: • resc ≥ 7 pc (X-high), resc ≥ 400 pc (D+Ea) • Neither are thermally driven. • Magnetocentrifugal acceleration: • Likely important, at least by comparison to other alternatives. • Gives large transverse velocities and large line widths (Bottorff et al. 2000)
Conclusions • There is an intermediate-line region (ILR) in NGC 4151, characterized by FWHM = 1170 km s-1. • The ILR is the same component of outflowing gas responsible for the high-column UV and X-ray absorption (D+Ea) at ~0.1 pc from the nucleus. • The ILR has Cg 0.4 and it shields the NLR, indicating outflow over a large solid angle centered on the accretion-disk axis. • The kinematics at this distance are likely dominated by rotation, but there is a significant outflow component (vT 2100 km s-1 and vr = - 490 km s-1). • A simple geometric model yields maximum emission-line velocities close to the observed HWZI of the ILR (1400 km s-1) and significantly less than vT. • The mass outflow rate is ~ 0.16 M yr-1, about 10x the accretion rate. • Dynamical considerations indicate that magnetocentrifugal acceleration is favored over pure radiation driving or thermal expansion. • Future work: compare these constraints with predictions from dynamical models (e.g., Proga 2003; Chelouche & Netzer 2005; Everett 2005).