The non-thermal broadband spectral energy distribution of radio galaxies

1. The non-thermal broadband spectral energy distribution of radio galaxies Gustavo E. Romero Instituto Argentino de Radio Astronomía (IAR-CCT La Plata CONICET) FCAG, Universidad Nacional de La Plata IAU SED 2011, Preston, UK, 5-9 September, 2011 Contact: romero@iar-conicet.gov.ar

2. AGNs produce gamma-ray emission

3. The “lepto/hadronic” jet model (in a nutshell) Physical conditions near the jet base are similar to those of the corona (e.g. Reynoso et al. 2011; Romero & Vila 2008, 2009; Vila & Romero 2010) The jet launching region is quite close to the central compact object (few Rg) Hot thermal plasma is injected at the base, equipartition b/w particles and magnetic field to start with. Jet plasma accelerates longitudinally due to pressure gradients, expands laterally with sound speed (Bosch-Ramon et al. 2006) The plasma cools as it moves outward along the jet. As the plasma accelerates the local magnetic field decreases. Maitra et al. (2009)

4. z zend zmax zacc z0 q j BH Jet Model – 1. Structure • z0 : base of the jet; ~50 Rg • zacc < z < zmax: acceleration region; injection of relativistic particles. • zend : “end” of the radiative jet • j : jet opening angle • q : viewing angle; moderate

5. Jet Model – 2. Power Content of relativistic particles… z

6. Jet Model – 3. Acceleration and losses Maximum energy determined by balance of cooling and acceleration rates • Acceleration: diffusive shock acceleration • Cooling processes: interaction with magnetic field, photon field and matter • Inverse Compton (IC or SSC) • Proton-photon collisions (pg) • Adiabatic cooling • Synchrotron • Relativistic Bremsstrahlung • Proton-proton collisions (pp)

7. Jet Model – 4. Particledistributions Calculation of particle distributions: injection, cooling, decay, and convection Also for secondary particles: charged pions, muons and electron-positron pairs • Direct pair production • Photomeson production & pp collisions

8. Radiativeprocesses in jets (e.g.Romero & Vila 2008, Vila & Aharonian 2009, Vila & Romero 2010) magnetic field Interaction of relativistic p and e- with in the jet matter radiation fields • Synchrotron radiation • * Inverse Compton (IC) • Relativistic Bremsstrhalung p + p  p + p + a 0+ b(+ +-) • Proton-proton inelastic collisions • Photohadronic interactions (pg)

9. See Bednarek’s many papers on the topic. Also Pellizza et al. 2010, and Bosch-Ramon & Khangulyan 2009 review. IC Cascades • Photon energy densities > magnetic energy density • Disc • Corona • Jet synchr. (SSC) Orellana et al. (2007)

10. Absorption Absorption in matter Photon-photon absorption

11. Example: Cen A Lj~6 x1044 erg/s Mbh~ 108 Mʘ

12. Losses (from Reynoso et al. 2011)

13. Absorption

14. SED

15. Example: M87 Lj~2 x1046 erg/s Mbh~ 6 x 109 Mʘ

16. Losses (from Reynoso et al. 2011)

17. Absorption

18. SED

19. Powerfulblazars - Variability PKS 2155-304

20. Powerfulblazars – Variability…radio/optical PKS 0537-441 Romero et al. (1994, 2000a, b)

21. Two-fluid jet model (Sol et al. 1989, Romero 1995, Reynoso et al. 2011) B B black hole jet A highly relativistic pair jet is driven by the ergosphere and the barion loaded jet is produced by the disk. Y disk wind - Y – magnetic flux accumulated by the BH

22. Two-fluid jet model Sol et al. (1989); Romero (1995, 1996); Roland et al. (2009)

23. Moll (2010) The axial magneticfieldwillpreventthedevelopment of inestabilitiesiflargerthanBc givenby: Kelvin-Helmholtz instabilities develop in the interface between both fluids. Romero (1995, 1996)

24. Shocks develop when the magnetic energy decreases and charged particles are re-accelerated by a Fermi-like mechanism (alternatives: converter mechanism – Derishev , local magnetic reconnection – Lyubarsky). Power-law populations of non-thermal particles are injected. These particles will interact with the local inhomogeneities, producing variable non-thermal radiation (Marscher 1992, Romero 1995).

25. The variability follows the inhomogenous structure of the beam, with regions of different photon field density (Qian et al. 1991, Romero et al 1995) Rapid variability Extreme TeV blazars Variability timescale; l is the linear size of the inhomegeneities. For l~1014-15 cm → tv~1-10 min

26. Changes in theopticalpolarization (Andruchow et al. 2005)

27. Fermi VERITAS CTA Anapplicationto a Galacticsource – Fittothespectrum of the LMMQ XTE J1118+480 2005 outburst • zacc= 6x108 cm zmax = 10 zacc • zend = 1012 cm • B(z) = K z-1.5 • h= 0.01 • Laccr = 0.1 LEdd Ljet ~ 5x1036 erg s-1 • Lrel = 0.1 Ljet Lp = 5 Le ~5x1035 erg s-1 • Emin = 50 mc2 Q= K’ E-1.5

28. Conclusions • Barion loaded jets with particle injection along inhomogeneous regions can explain the non-thermal spectral energy distribution of AGNs. • Electron-positron beams moving inside the hadronic jets can play a role in the generation of non-thermal rapid variability. • The fine resolution in HE SED and the rapid variability obtained with the future CTA Observatory can be used to constrain this tipe of models and the location of the emission region in the sources.

29. Thankyou!

32. Cen A

33. M 87

36. Evolution of thebulkLorentz factor