Multi-Wavelength Time Variability of Active Galactic Nuclei Ritaban Chatterjee Advisor: Prof. Alan...
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Transcript of Multi-Wavelength Time Variability of Active Galactic Nuclei Ritaban Chatterjee Advisor: Prof. Alan...
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).
3C 279 : X-ray-optical Cross-Correlation
• Optical leads X-ray by ~ 19 Days
Chatterjee et al. 2008(ApJ, 489, 79)
X-ray and Optical : Superposed
Compare:1. Time lag between peaks2. Energy output
of flares : Area under the
curve
Time Lag (Days) X/Op Ratio
1. -27 0.4
2. -24 0.62
3. -49 0.67
4. -15 0.44
5. -22 1.4
6. 16 0.18
7. 25 0.38
8. 27 0.3
9. -3 0.95
10. -8 0.98
11. -3 0.87
12. -6 0.88
Larger time delay,Ratio<1
Smaller time delay,Ratio ~1
• 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, N0 ~r-n, R ~r
∆t smallerx/op~1
∆t largerx/op<1
Upstream Downstream
Sketch of emission regions at two different locations in the jet
Larger time delay,Smaller ratio
Smaller time delay,Ratio ~1
Time Lag (Days) X/Op Ratio
1. -27 0.4
2. -24 0.62
3. -49 0.67
4. -15 0.44
5. -22 1.4
6. 16 0.18
7. 25 0.38
8. 27 0.3
9. -3 0.95
10. -8 0.98
11. -3 0.87
12. -6 0.88
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 << 1 => farther from the base of the jet
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.