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Multi-Wavelength Time Variability of Active Galactic Nuclei Ritaban Chatterjee Advisor: Prof. Alan P. Marscher Collaborators: Svetlana Jorstad (B.U.), Phil Uttley (U. Southampton, UK).
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Why Time Variability?
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3C 279 Z=0.536 1 mas = 6.3 pc 3C 279
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3C 279 RESULTS
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X-RAY OPTICAL RADIO Monitoring of 3C 279 between 1996-2007
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3C 279 : X-ray-optical Cross-Correlation Optical leads X-ray by ~ 19 Days Chatterjee et al. 2008 (ApJ, 489, 79)
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Correlation Time Window
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X-ray and Optical : Superposed Compare: 1. Time lag between peaks 2. Energy output of flares : Area under the curve
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Time Lag (Days) X/Op Ratio 1.-270.4 2.-240.62 3.-490.67 4.-150.44 5.-221.4 6.160.18 7.250.38 8.270.3 9.-30.95 10.-80.98 11.-30.87 12.-60.88 Larger time delay, Ratio<1 Smaller time delay, Ratio ~1
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Optical => Synchrotron X-ray=> Synchrotron self-Compton (SSC) Simulation of time variable non-thermal radiation Modeling of synchrotron (optical) and synchrotron self-Compton (X-ray) flares B ~r -b, N 0 ~r -n, R ~r
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Real and Simulated Light Curves Chatterjee et al. (submitted to ApJ)
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Real and Simulated Light Curves SIMULATEDREAL Chatterjee et al. (submitted to ApJ)
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Downstream SSC (Green) maybe smaller than Synchrotron (Red) UPSTREAMDOWNSTREAM
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Sketch of emission regions at two different locations in the jet x/op~1 x/op<1 UpstreamDownstream
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∆ t smaller x/op~1 ∆ t larger x/op<1 UpstreamDownstream Sketch of emission regions at two different locations in the jet
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Larger time delay, Smaller ratio Smaller time delay, Ratio ~1 Time Lag (Days) X/Op Ratio 1.-270.4 2.-240.62 3.-490.67 4.-150.44 5.-221.4 6.160.18 7.250.38 8.270.3 9.-30.95 10.-80.98 11.-30.87 12.-60.88
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CONCLUSIONS: LOCATION AND MECHANISM OF EMISSION X-ray and optical variations are highly correlated. X-ray/optical correlation changes over time. Contemporaneous X-ray and optical flares: X/OP ≈ 1 => closer to the base of the jet X/OP farther from the base of the jet
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3C 120 RESULTS : X-RAY
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X-RAY OPTICAL RADIO Light Curves of 3C 120 between 2002 and 2007
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Variability at different timescales
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3C 120 X-Ray Power Spectral Density (PSD) Break Frequency =10 -5 Hz Break Time Scale =2 Days
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X-Ray PSD of Cygnus X-1 : Break Credit : Uttley et al. (2004) BH Mass vs. Break Time Scale
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X-Ray PSD of Cygnus X-1 : Break Credit : Uttley et al. (2004) BH Mass vs. Break Time Scale 3C 120
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3C 120 RESULTS : X-Ray/Radio
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X-RAY OPTICAL RADIO Light Curves of 3C 120 between 2002 and 2007
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X-ray Dips and 37 GHz Flares
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X-ray/37 GHz Anti-correlation (X-ray leads 37GHz by 120 days) Chatterjee et al. 2009 (in prep)
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Possible Explanation of the X-ray Dip and Superluminal Ejection Correlation 1. Change in the magnetic field configuration in the accretion disk from turbulent to aligned => absence of viscous heating causes dips in X-ray production => aligned B field configuration facilitates shock to move towards the jet (Livio et al. 2003) 2. Corona is the base of the jet => decrease in the number density of electrons at the base of the jet => causes X-ray dips and increase in the speed of particles (continuity eqn.) => causes shock wave.
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THE END
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X-ray light curve : Sum of model flares & real data Chatterjee et al. 2008 (ApJ, 689, 79)
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Optical light curve : Sum of model flares & real data Chatterjee et al. 2008 (ApJ, 689, 79)
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3C 120 X-Ray Power Spectral Density (PSD) Break Frequency =10 -5 Hz Break Time Scale =2 Days
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