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Numerical Modeling of Electromagnetic Radiation from AGN Jets

Numerical Modeling of Electromagnetic Radiation from AGN Jets. Based on. -ray emission and spectral evolution of pair plasmas in AGN jets Bottcher et al. Astronomy and Astrophysics Vol. 324 1997. Giridhar Nandikotkur. Numerical Modeling of Electromagnetic Radiation from AGN Jets.

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Numerical Modeling of Electromagnetic Radiation from AGN Jets

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  1. Numerical Modeling of Electromagnetic Radiation from AGN Jets Based on -ray emission and spectral evolution of pair plasmas in AGN jets Bottcher et al.Astronomy and Astrophysics Vol. 324 1997 Giridhar Nandikotkur

  2. Numerical Modeling of Electromagnetic Radiation from AGN Jets • What are Active Galactic Nuclei (AGN)? • Structure • Historical Existence • Physical Processes • Experiment leading to theory • a chronological journey • Current Status of theoretical methods • First step- a small one

  3. What are Active Galactic Nuclei (AGNs)? • Historical Existence • Extra-galactic • measured redshifts • Extremely bright and violent • presence of jets at all wavelengths • Estimated energy more than of order of 10^60 ergs! • Something gravitational in nature • Sharp rise in Luminosity towards the center • Massive object at the center-black hole?

  4. What are Active Galactic Nuclei (AGNs)? • Structure • Black hole at the center • Accretion disc • Jet • Clouds at some distance • Ordered magnetic filed lines emanating from BH

  5. Physical Processes • Synchrotron Radiation • suggested by polarization measurements • Experimentally observation: Power law energyspectrum • can be produced by power law distribution of electrons

  6. Physical Processes • Photon Scattering by Inverse Comton emission • Thompson scattering • - non-relativistic • Compton Scattering • - relativistic: Klein-Nishina

  7. Physical Processes • Broadband Spectrum • Synchrotron radiation has a peak and (dF/dlog) = F vs.  • will show a peak. Peak around optical-UV • falls towards UV, Xrays • Compton Gamma Ray Observatory Launch 1991 • Detection of sources with high energy gamma ray emission • Bulk of their luminosity in Gamma rays • A second peak in the broad band spectrum • Explanation by Inverse Compton emission

  8. Peak 1:Synchrotron Radiation Peak 2. Accretion Disk Black Body Peak 3. Self Synchrotron Emission (SSC) Peak 4. External Comption Disk (ECD) Peak 5. External Compton clouds (ECC) Ac. Disk B. Hole Torus Electrons Photons BLR SED for FSRQ

  9. Theoretical Approaches • Numerical Model. • Assume an injected leptonic (e+ e-) plasma blob with power law distribution. • Evolution of photon and electron distributions using emission and absorption processes.

  10. Power Law: N()d = C  -s d C: Normalization constant  N()d = No Energy Losses (d  /dt)synchrotron ; (d  /dt)SSC ; Numerical Integration (d  /dt)ECD ; (d  /dt)ECC ; Change in particle distribution t = 0 + t * (d  /dt)ECDForward Euler Photon Spectrum at each time step

  11. Simulation of ECD process Scattering of accretion disk photons of electrons mathematica postscript

  12. Has to match exactly with the paper. If not, find the parameter that is different in the initialization

  13. Future Work • Include other processes. • Generate Photon Spectrum • Explore Gaussian Quadrature to Numerically integrate. • Ambitious Target: 3 months!

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