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:

2 AGNs produce gamma-ray emission

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) 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 R g ) 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)

Jet Model – 1. Structure z 0 : base of the jet; ~50 R g z acc < z < z max : acceleration region; injection of relativistic particles. z end : “ end ” of the radiative jet  : jet opening angle  : viewing angle; moderate z0z0 z acc z max z BH z end  

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

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 Synchrotron Relativistic Bremsstrahlung Proton-proton collisions (pp) Inverse Compton (IC or SSC) Proton-photon collisions (p  ) Adiabatic cooling

Jet Model – 4. Particle distributions 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

Non-thermal radiative processes in jets Relativistic particles: Relativistic particles: electrons, protons, secondary particles (  ±,  ±, e ± ) Target fields: Target fields: magnetic fields, radiation fields, matter fields Acceleration mechanism Diffusive shock acceleration Converter mechanism, … Target fields Internal: Internal: locally generated photon fields, magnetic field, comoving matter field stellar winds and photons, accretion disc photons, clumps, clouds, ISM… External: External: depending on the context e-e- p p  ±  ± e ±  shock     

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

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

Absorption Absorption in matter Photon-photon absorption

Example: Cen A L j ~6 x10 44 erg/s M bh ~ 10 8 M ʘ

Losses (from Reynoso et al. 2011)

Absorption

SED

Example: M87 L j ~2 x10 46 erg/s M bh ~ 6 x 10 9 M ʘ

Losses (from Reynoso et al. 2011)

Absorption

SED

Powerful blazars - Variability PKS

Powerful blazars – Variability…radio/optical Romero et al. (1994, 2000a, b) PKS

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

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

Romero (1995, 1996) Kelvin-Helmholtz instabilities develop in the interface between both fluids. The axial magnetic field will prevent the development of inestabilities if larger than B c given by: Moll (2010)

25 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).

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

Changes in the optical polarization (Andruchow et al. 2005)

An application to a Galactic source – Fit to the spectrum of the LMMQ XTE J Fit to the spectrum of the LMMQ XTE J Fermi VERITAS CTA z acc = 6x10 8 cm z max = 10 z acc z end = cm B(z) = K z -1.5  = 0.01 L accr = 0.1 L Edd L jet ~ 5x10 36 erg s -1 L rel = 0.1 L jet L p = 5 L e ~ 5x10 35 erg s -1 E min = 50 mc 2 Q= K’ E outburst

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.

Thank you!

Cen A

M 87

Evolution of the bulk Lorentz factor