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The two-flow model : a unifying paradigm for AGNs and microquasars relativistic jets. G. Henri Laboratoire d ’Astrophysique de Grenoble, France Coll: G.Pelletier, J. Ferreira, P.O. Petrucci Students : A. Marcowith, N. Renaud, L. Saugé, T.Boutelier.
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The two-flow model : a unifying paradigm for AGNs and microquasarsrelativistic jets. G. Henri Laboratoire d ’Astrophysique de Grenoble, France Coll: G.Pelletier, J. Ferreira, P.O. Petrucci Students : A. Marcowith, N. Renaud, L. Saugé, T.Boutelier Relativistic Jets, Ann Arbor 2005
Why are relativistic jets difficult to produce? • Require a very high magnetization or thermal enthalpy (very low baryon load < Gb-1 ) : must be assumed a priori (very far from equipartition). • Difficult to collimate : relativistic E field decollimates the jet (but see Vlahakis & Königl ‘04 ?). • Subject to Compton Drag, especially for light e--e+ jets. Relativistic Jets, Ann Arbor 2005
Evidence for different ejection velocities GRS 1915+105 Relativistic ejections during flares : superluminal velocities (Mirabel Rodriguez ‘94) • Compact jets observed during low-hard « plateau » states • Brightness contrast implies b ~ 0.1 to 0.5 (Dhawan ‘00) Two-sided jet @ kpc scale AGN e.g. 1928+134 (Hummel et al. 1992) One sided jet @ pc scale superluminal motion, vapp = 6 c Either q is varying by ~ 50° Or Gb is varying from 7 to 1.08…. Relativistic Jets, Ann Arbor 2005
The « Two flow » model Two flow model : 2 distinct flows (Sol, Pelletier, Asséo ‘85, H. & Pelletier ‘91), introduced first for explaining radio observations. MHD jet e- p+ mildly relativistic *carries most of the power *fuelled by accretion disk *large scale structures, hotspots + • Ultra relativistic e+-e-pair plasma • * Generated in the « empty » funnel, no baryon load. • * Produces high energy photons and relativistic motions • * Energetically minor component Relativistic Jets, Ann Arbor 2005
The « slow » MHD component Baryonic jet can be emitted from the accretion disk through MHD mechanism ( a la Blandford-Payne) (Ferreira et al., ‘97, ‘04) B field extract angular momentum and power from the JED (Jet Emitting Disk) Disk weakly radiative (mimic ADAF) Jet only mildly relativistic under self consistent accretion-ejection conditions m=pB/(pg+prad) ~ 0.1 to 1 NB :curvature of B field lines can be achieved because vr/vKepl =h/r (SS : vr/vKepl =(h/r)2) Relativistic Jets, Ann Arbor 2005
Formation of the « fast » pair plasma In situ generation of pair plasma in the MHD funnel (H.& Pelletier 91, Marcowith et al. ‘95) Produced through gamma-ray emission • Injection of some relativistic particles • X-ray and gamma-ray emission by IC and/or SSC • g-g annihilation forms new pairs • Continuous reacceleration by MHD turbulence necessary for a pair runaway to develop. • Limited by the free energy available: saturation must occur at some point. Relativistic Jets, Ann Arbor 2005
Cold plasma What is the effect of « Compton Drag » ? Common wisdom :Inverse Compton process tends to slow relativistic jets But Anisotropic Inverse Compton acts more like an « automatic pilot» ! Sets up an « equilibrium » Lorentz factor for which the aberrated net flux vanishes Geq ~ (z/Ri)1/4 On the axis of a standard accretion disk predicts progressive acceleration along the axis, but rather inefficient for a single particle (cold plasma) :saturates @ Gb Gb∞~ ls1/7 ~ 3 z/rg Relativistic Jets, Ann Arbor 2005
Hot plasma Cold plasma Gb S=1.5 S=2 S=2.5 S=3 Getting relativistic: Bulk acceleration of rekativistic pair plasma Efficiency of radiative acceleration much higher for hot relativistic plasma (Compton « rocket » effect, O’Dell ‘81) but requires continuous reacceleration.,only possible with an external energy reservoir : surroundig MHD jet Gb∞~ (ls <g2>/<g>)1/7 ~ 10 Gb∞~ ls1/7 ~ 3 M = 10 Msol M = 108 Msol Precise calculations : maximum efficiency limited by Klein-Nishina cut-off : Lower value for µ-quasars than for AGNs (Renaud & H. ‘98) S=1.5 S=2 S=2.5 S=3 Relativistic Jets, Ann Arbor 2005
Application to microquasars We propose to interpret the various canonical states of X-ray binaries and µ quasars in the frame of the 2-flow model (Ferreira ‘06) Quiescent Low-hard Subrelativistic compact jet Very High Intermediate Superluminal ejections, pairs produced by the non-thermal power-law Thermal soft Relativistic Jets, Ann Arbor 2005
Application to AGN spectra : a complete spectral fit of 3C279 data. Relativistic Jets, Ann Arbor 2005
Some words about variability • Transition radius can be located at large distance (but non radiative JED does exist inside) : LF QPO associated with the jet/corona. • Pair production naturally explosive : quenching mechanism when tapping the energy from the surrounding jet (Saugé, PhD 2004) Luminosity Photons Constant injection Energy reservoir Radiative cooling Pair creation Pairs acceleration Relativistic Jets, Ann Arbor 2005
The « Doppler factor crisis » of TeV blazars In most TeV blazars,gg transparency arguments require high Doppler factor ~ 50 in all « one zone SSC » models. • But other arguments indicates much lower values • Absence of high superluminal motions • Low brightness temperatures • Detection of unbeamed radio-galaxies in g-rays • Cen A (EGRET), M87 (HEGRA, HESS) • Unification models BL Lacs-FRI • Luminosity ratio • Number of sources Converge all to G~3 - 5 Fast spine in jet solves some problems but not all ! Relativistic Jets, Ann Arbor 2005
A clue to the issue : inhomogeneous jet gg transparency implies an upper limit on local soft photon density, depending on d Homogeneous models require d~50 • Assuming d = 3 implies • * inhomogeneous emission zone • (stratified jet ) • * Local monoenergetic or quasi-maxwellian distribution • Moderately high tgg tgg=1 H. & Saugé ‘06 All of these being natural outcomes of two-flow model. Relativistic Jets, Ann Arbor 2005
Summary • 2-flow model can account for most observational and theoretical constraints of relativistic jets • Requires only powerful subrelativistic jet and non thermal acceleration process (which are required anyway): generate self consistently a relativistic pair plasma. • Can account for superluminal motion, radiative processes and variability • Time dependant, realistic 3D simulations under work to compare with observations (HESS, m quasars) Relativistic Jets, Ann Arbor 2005