AGN Outflows: Part II Outflow Generation Mechanisms: Models and Observations Leah Simon May 4, 2006

Review: Unified Model

Review: Outflows exist BALs (Broad Absorption Lines)  Large velocity widths: V(FWHM) > 3000 km/s  Within ~60,000km/s of quasar redshift (v ~ 0.2c) Variability: timescales of ~year(s)  Caused by continuum source variability affecting photoionized clouds  Or caused by cloud (outflow) motion across LOS Partial coverage  Continuum source is small!  Cloud must be nearby if some continuum source can pass around cloud to our eye

Review: Acceleration Mechanisms Radiation Pressure (Photoionization)  Line Driving – momentum from radiation field through line opacity  Expect v transverse = small  Require very high L/L Edd Thermal Pressure (Parker Wind)  Not strong enough  Requires Isothermal wind... Magnetic Pressure (Magnetocentrifugal Driving)  'Beads on a string'  See John Everett (CITA)

MHD vs LD MagnetoHydroDynam ics  Does not necessitate shielding (over- ionization unimportant)  Expected from collimated radio jets  Predicts high velocity flows, and can move high-density gas Line Driving  Requires shield to protect wind from inner x-ray radiation  UV flux and wind velocities correlate  Radiative momentum lost from continuum found in BALs  Can explain relative X-ray and UV flux well  Predicts high velocity outflows, but maybe densities too low

Probably a combination of the the two methods (Everett 2005, Proga, 2003). Need to constrain models to distinguish between them!

Proga 2003 simulates MHD+LD using both poloidal and toroidal B-fields Similar to LD, but with faster (slow) dense wind at outer disk Fluid angular- momentum- conservation Not magneto- centrifugal wind Mass loss through LD at inner disk (fast stream) through MHD at outer disk (slow stream)

Observational Evidence: General Results CIV width relates to L xray Proga 2005, Proga + Kallman 2004  Are UV and and X-ray radiatively coupled? X-ray absorption Gallagher et al  Hardest X-ray spectra are also weakest – intrinsic absorption? Shielding and/or Over-ionization Proga, Everett, Murray et al  Line driving requires shielding to protect from over- ionization  Hot corona? What's all the buzz?

Using Gravitational Lensing Use multiple LOS to compare structural models for BLR  Virialized clouds (Kaspi & Netzer 1999)  Continuously outflowing wind ( Murray et al. 1995) How it works  observe lensed BALQSOs  compare 2 observations  Infer geometry based on variation among LOS D. Chelouche, ApJ 2003

Gravitational Lensing Results Chelouche finds lensed troughs are similar to within S/N for all but 2 quasars Single Cloud Model:  lateral size of clouds must be smaller than R S - expected based on partial coverage  For non-varying clouds, must have lateral to radial aspect ratio ~ Would be destroyed on dynamical timescale – no coherent acceleration --NO  Tube model - many (n) identical clouds with aspect ratio also << 1 - alignment of tube over numerous LOS unlikely --NO Clumpy Wind Model:  Cloudlets imply statistical isotropy: different LOS views same distribution – variation should follow Poissonian distribution  similarities imply n v >>1 and n tot >>100  changes imply change in cloud distribution function –YES  implies isotropy on ~few arcsec scale – BAL Outflow probably one or many sheets or cones with large lateral size – not time- dependent dynamical wind

Evidence for Multiphase Flows de Kool et al observe disparate ionization states at similar velocities-conclude shielded gas at large distances (~1kpc) Everett et al re-evaluate and conclude multiphase flow, with continuous low-density wind and embedded high density clouds at small distances (~4pc)  Inner continuous region acts as shield, driven by MHD or failed LD  Outer region is LD outflow, with lower ionizations  Lowest ionizations found in dense embedded clouds → Centrifugally driven disk wind? Turbulence? Shocks?

Multiphase Flow in NALs? Observe CIV and CII at same velocities Initial distance determinations locate SiII very far from source (~150 kpc) Combine with partial coverage in CIV! Could multiphase flow be a solution?

Variability Test Observation Separation PKS 2204 ~ 13 years Q 0401 ~ 7 years PKS 2044 ~ 17 years Q 0249 ~ 14 years Q 0334 ~ 14 years Approximate Variability Timescales Accretion disk size ~.1pc Light crossing time ~.35 years Viscous time ~ 200 years Dynamical time ~ 0.3 days Using M=10 8 M sun, R=2x10 14 ~3R S (X-ray source size)

Thanks!