Mike Crenshaw (Georgia State University) Steve Kraemer (Catholic University of America)

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