Mike Crenshaw (Georgia State University)

Steve Kraemer(Catholic University of America)

Mass Outflows from AGN in Emission and Absorption

NGC 4151

IUE: black plusesHUT: red diamondsFOS: green trianglesSTIS: blue x’s

• 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

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.

(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 C IV Region

Absorption Variability in X-rays

• 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

(Kraemer et al. 2005, ApJ, 633, 693)

• 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?

Photoionization Models of High-Column Absorbers

Yes! D+Ea is seen in emission.

Emission-Line Profiles at Low Flux Levels

• 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

• 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

C IV blue - narrowred - intermediategreen - broad

blue - narrowred - intermediategreen - broad

Intermediate Components in Other Lines

(Crenshaw & Kraemer, 2006, ApJ, submitted)

ILR Line Ratios and D+Ea Photoionization Models

• 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

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

• High-N model is a better match globally• Scale factor for High-N model gives Cg = 0.4

(global covering factor)

+ Observed--- High-N Model… Low-N Model

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)

• 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)

Dynamical Considerations

resc GMmH Tgk

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).

THE END