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Probing AGN Outflows with Variability. Smita Mathur Ohio State. Collaborators: Yair Krongold, Fabrizio Nicastro, Anjali Gupta Nancy Brickhouse, Martin Elvis. Outburst in NGC 2617. Seyfert 1.8 Seyfert 1. Swift monitoring. + XMM. Outflows are ubiquitous.
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Probing AGN Outflows with Variability Smita Mathur Ohio State Collaborators: Yair Krongold, Fabrizio Nicastro, Anjali Gupta Nancy Brickhouse, Martin Elvis
Swift monitoring + XMM
Outflows are ubiquitous Seen in 50% of Seyfert galaxies. NGC 3783 HST and FUSE
Physical models of outflow • Accretion disk winds: Proga et al. - small physical scale • Winds off obscuring torus: Krolik & Kriss - on pc to 10s of pc scale • Outflowing NLR • Host galaxy ISM
Disk winds Elvis 2000
AGN outflows • Ubiquitous • Location, physical properties not well known until recently • Accretion disk winds? • Dependence on black hole mass/ Eddington luminosity ratio
What is the distance of the absorber from the nucleus? Proposals span a factor of > 106 from accretion disk to Kpc scale narrow line region n R2
How to measure the density? • Metastable absorption lines. - He I*, C II*, C III* - low ionization lines : distinct parameter space - Non-detection NOT constraining • Variability
Variability Density Distance
There can be variability due to absorber crossing line of sight. But Absorber must vary in responses to changes in ionizing continuum.
Why is this a hard measurement? • X-rays: Integration times too large (one day = 86.4 ks) • UV: need many observations with dense time sampling lots of HST orbits
XMM Observations of NGC 4051 • RGS High resolution spectrum • EPIC Variability
Log count rate Log U Log U 0 2 10 Time 104 s
R (HIP) = 0.5-1.0 lt days. (2300-4600 RS) R (LIP) = < 3.5 lt days. (< 15800 RS) BH mass in NGC 4051 is 2 x 106 M⊙
The outflow is clearly compact …consistent with an accretion disk origin. Rule out various models: - wind off torus edge (Krolik & Kriss) - continuous range of ionization parameter (Ogle et al.)
Mass & Energy outflow rates HIP & LIP mass outflow rates: ~ 1 x 10-4 M⊙ yr-1 c.f. accretion rate: ~ 5 x 10-3 M⊙ yr-1
Kinetic power released: ~1038 erg/s c.f. bolometric luminosity: 2.5 x 1043 erg/s Energy injection rate in the surrounding medium is significantly smaller than that required by feedback models Scannapieco Silk
Observational evidence for accretion disk winds is scarce Short time-scale variability remains an unexplored region of the parameter space.
Sparse sampling naturally leads to large radial distance. • Often radial distance is assumed to be that with escape velocity = outflow velocity. • Distance derived from metastable states is assumed for high ionization outflow.
…..But what about luminous quasars? Dietrich et al. in prep.
Seyferts are NOT scaled down Quasars L Merger Merger Z Secular Secular
Future directions • Intra-day time resolved spectroscopy • X-ray: XMM advantage -- CCD and gratings • UV: HST COS -- exquisite sensitivity
Robust detection V ~ 0.1c Gupta et al. 2013
Magneto-hydrodynamic wind? Gupta et al. 2013b