Multi - emission from large-scale jets Fabrizio Tavecchio INAF Osservatorio Astronomico di Brera Outline Introduction X-rays from radiogalaxies: synchrotron from HE electrons X-ray jets in QSO: the IC/CMB model Recent observations Criticisms, alternatives Almost every galaxy hosts a BH 99 % are silent 1 % are active 0.1% have jets Cygnus A Relativistic jets: channels transporting MassMomentumEnergy from the central BH to the IGM core Hot spots lobes The unification scheme: radiogalaxy, RL QSOs blazar Jets: from the BH to large scale Resolved X-ray jet Blazar emission region Accretion region VLBI region X-rays: a new window on old problems Acceleration and collimation Power, composition Particle acceleration Siemiginowska et al PKS Chartas et al Cen A Hardcastle et al Pic A Wilson et al. 2000 Producing X-rays in large-scale jets Powerful (aligned) QSOs IC/CMB Tavecchio et al Celotti et al Synchrotron SSC thermal Schwartz et al very energetic electrons Radiogalaxies FRIs: Synchrotron e.g Worrall et al. 2001, 2002 FRIIs: Synch? SSC? e.g Wilson et al. 2001 Pesce et al C371: a synchrotron jet Knot B Knot A e ~10 7 X-rays radiooptical M87 Very high-energy electrons ( e ~10 7 ) injected in-situ within the jet (shocks? reconnection?) Radiogalaxies (FRI): Powerful QSOs Synchrotron IC/CMB at >100 kpc Amplification of the CMB energy density =10 Photons will appear more concentrated in time and with an energy U~U 2 =10 L=1 L=160,000 L= L=3x Amplification of the emission = [ (1- cos )] -1 Parameter space Equipartition (radio) IC with CMB (radio and X-rays) small ~5 deg ~10 ~10 A Chandra-HST survey of jets 17 radio selected jets 10 with X-rays (59%) 10 with optical Sambruna et al Sambruna et al IC/CMB knots Deep images Synchrotron to Compton transition? Speed and power The model allows us to constrain the physical parameters of jets at kpc scale ~3-10 P~ erg/s Supported by recent numerical simulations (Scheck et al. 2002), but see Wardle & Aaron 1997 Fast spine? (Chiaberge et al. 2000; Celotti et al. 2001) Problems, criticisms, alternatives Cooling: why X-ray knots? Large power requirements (~10 48 erg/s) Close alignement (small prob.) Clumps in jets? cannot cool Problem: the X-ray emitting electrons cannot cool inside the knot even including adiabatic losses! Tavecchio, Ghisellini & Celotti 2003 A possible solution Several compact regions overpressured with respect to the external plasma (instabilities, clouds, entrained material, reconnection sites) Consequence: expected variability in knots (~month) expansion very efficient adiabatic losses New evidences: Several knots in M87 are variable! (Harris et al. 2003) Cen A shows compact X-ray/radio knots (Hardcastle et al. 2003) Synchrotron from complex electron distributions: Alternatives to the IC/CMB: Dermer & Atoyan 2002 ~ cooled electrons uncooled electrons From cooling or from acceleration Multiple shocks or turbulence (Stawarz et al. 2004): Marcovith & Kirk 1999 Synchrotron from another electron component or from HE protons Aharonian 2002 Secondary electrons could be produced through p- or p-p inefficient, Urad quite small a density of ~1 part/cm 3 is necessary Aharonian 2002 Summary The IC/CMB model works well for powerful jets in QSO Deep pointings reveal synchrotron to IC transition along the jet Radiogalaxies: a unique synchrotron component from radio to X-rays acceleration mechanism? BUT: problems with low E electrons: clumps? More observations and exploration of alternatives From subpc to kpc-scale Blazars and Chandra: physical quantities at (very) different scales! Example: (z=0.361) B=2G; R=3x10 cm 16 B=0.6x10 G; R=2x10 cm -522 Problems, criticisms, alternatives Cooling: how to produce X-ray knots? Large power requirements (~10 48 erg/s) Close alignement (small prob.) Global behaviour (but see G&K 2003) { Layer and spine M87 PKS Siemiginowska et al Offsets? Evidences for small angles from superluminal motions: Lorentz factor Angle