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Extreme-Astrophysics in an Ever-Changing Universe 19.06.2014, Ierapetra

Time dependent modeling of AGN emission from inhomogeneous jets with Particle diffusion and localized acceleration. Xuhui Chen University of Potsdam & DESY Collaborators: Martin Pohl (University of Potsdam; DESY, Germany); Markus Boettcher (North-West Uni., South Africa ).

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Extreme-Astrophysics in an Ever-Changing Universe 19.06.2014, Ierapetra

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  1. Time dependent modeling of AGN emission from inhomogeneous jets with Particle diffusion and localized acceleration Xuhui Chen University of Potsdam & DESY Collaborators: Martin Pohl (University of Potsdam; DESY, Germany); Markus Boettcher (North-West Uni., South Africa ) Extreme-Astrophysics in an Ever-Changing Universe 19.06.2014, Ierapetra

  2. Outline Introduction and model setup Closed boundary scenario Open boundary scenario Discussion 2

  3. Blazar Emission Region Ultra-fast flares in BL Lacs – small emission region (~10 -4 pc) FSRQs detected above 100 GeV – far away emission region (~pc) (PKS 2155-304, HESS collaboration 2007) (3C279, MAGIC collaboration, 2008) 3

  4. Sketch of the 2D cylindrical geometry 2nd order Fermi Acceleration Through Fokker-Planck equation: Spatial diffusion of particles Through Fick's law: 4 (Chen et al. 2011,2014)

  5. Radiation: Monte Carlo Comptonization • Synchrotron radiation • Synchrotron Self-Comptonization (SSC) including inter-zone illumination and light travel time effects (LTTEs) Homogeneous magnetic field used in this study Observer. Relativistic beaming 5 (Chen et al. 2011,2014)

  6. Outline Introduction and model setup Closed boundary scenario Open boundary scenario Discussion 6 (Solar Prominence,credit to ESA and NASA)

  7. Accelerator in the center--Electron energy density map evolution Closed boundary the acceleration region occupies 2x2 zones 7

  8. Accelerator in the center--Zone specific electron energy distribution (EED) Closed boundary Inner zone --accelerated Mid zone Outer zone --cooled 8

  9. Accelerator in the center--Total EED and spectral energy distribution (SED) Closed boundary Comparison with Mrk 421 data (Abdo et al. 2011) 9

  10. Accelerator in the center--Energy dependent inhomogeneity Closed boundary Consequences: 1. Energy dependent AGN emission region 2. Weak pair creation compactness constraint 3. SSC has harder spectrum than synchrotron 10

  11. Accelerator in the center--Total EED and spectral energy distribution (SED) Closed boundary Spectral index: -0.71, -0.59 Comparison with Mrk 421 data (Abdo et al. 2011) 11

  12. If the diffusion is slow... Closed boundary Spectral hardening at high energy Spectral index: -0.6, -0.51 12

  13. Outline Introduction and model setup Closed boundary scenario Open boundary scenario Discussion 13 (Figure from Federrath et al. 2011)

  14. Accelerator in the center Open boundary Lower energy particles are injected in the acceleration region, to compensate for the particle loss through escape. EED develops into a steady broken power-law 14

  15. Accelerator in the center Open boundary Lower energy particles are injected in the acceleration region, to compensate for the particle loss through escape. SED also shows broken power-law 15

  16. Accelerator away from the center Open boundary Spectral break smaller compared to the 'center' case (magenta line) 16

  17. Injection not at the Accelerator Open boundary Particles are injected in the center; but accelerated close to the boundary EED at high energy identical to the 'away' case (orange line) 17

  18. Injection not at the Accelerator Open boundary Particles are injected in the center; but accelerated close to the boundary Radio excess in the SED 18

  19. Outline Introduction Closed boundary scenario Open boundary scenario Discussion 19

  20. Summary • Localized particle acceleration with diffusive particle escape produces electron distribution that can explain AGN emissions • Energy dependent inhomogeneity causes the SSC spectrum to be harder than the synchrotron spectrum • Slow diffusion may lead to spectral hardening of the total EED at high energy • Acceleration away from the emission center leads to atypical broken power-law electron spectrum with break less than 1. 20

  21. Future work • Simulation of flares with similar setup • Energy dependent diffusion and acceleration • Anisotropic diffusion • Use random acceleration to replace continuous acceleration 21

  22. Reference Abdo et al. 2011, ApJ, 736,131 Chen et al. 2011, MNRAS, 416, 2368 Chen et al. 2014, MNRAS, in press Federrath et al. 2011, ApJ, 731, 62 HESS collaboration, ApJ, 664, 71 MAGIC collaboration, science, 2008, 320, 1752

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