THE ASTROPHYSICAL JETS Wolfgang Kundt Washington, 27 July 2007 Vulcano, 27 May 2010
THE BIPOLAR-FLOW FAMILY • Jets from the centers of (active) galaxies (AGN) • Jets from young binary neutron stars (or BHCs). • Jets from forming white dwarfs, inside planetary nebulae (PNe). • Jets from newly-formed Stars (or YSOs), like our Sun, or even from newly-formed Brown Dwarfs.
CONSTRAINTS • Supply: rate (abundant), duration ( � 10 Myr), hardness (10 2 � γ � 10 7 ). • Stability: no splitting ever, stiffness (only mild bending), jet opening angle ( � 1%), weak propagation losses. • Efficiency: lobe/core power ratio ≈ 1%. • Sidedness and superluminality: γ � 1. • Spectra: hardness ( � TeV), synchrotron plus inverse (self) Compton, require large γ ‘s . • Weak synchrotron cooling (on Mpc scales, wt. in-situ). • Head propagation speeds: given by ram-pressure balance, want low (non-hadronic) inertia of jet medium.
JET PROPERTIES • Jet medium { lighter , heavier} than environs, { leptonic , hadronic, multi-fluid}? e ± -plasma ! • Particle Creation {via B-reconnection , else}? • Particle Acceleration { by CE , in-situ}? • Jet Focussing { inertial , magnetic}? • Jet Propagation { E x B -drift , MHD}? • Jet Radiation non-thermal: { leptonic , hadronic} plus thermal: by channel-wall material; upto TeV-energies. • Central Engine { universal , various}? Rotating Magnet! • ∆ W = e ∫ ( E + β β x B ) · d x = 10 12 eV β -3 B 6 dx 6.5 . β β
FORMATION • Relativistic pair plasma created in magnetic reconnections. • Post-Acceleration of the pair plasma by buoyancy and by Low-Frequency Waves. • Cooling of escaping pair plasma via thermal photon bath. • Jet Formation by traversing a self-swept deLaval nozzle. • On crossing the nozzle, the charges´ energy distribution changes from a relativistic Maxwellian to a delta function, via a self-generated (axi-symmetric) E x B -drift. • Repeated self-focussing of the jet by the inertia of the ambient CJM, of de Laval-nozzle type .
PROPAGATION • An axisymmetric approximation can be modelled analytical- ly, with E rad = B tor , j ≈ ρ c, r ρ (r=0) ≠ 0, with equipartition of energy densities of particles and fields, and with vanish- ing (synchrotron) radiation, as a radial Fourier expansion. • An additional longitudinal B -field is an option. • The mono-energetic spectrum of the leptons is stabilized by the E x B -drift.
TERMINATION • When a jet encounters (conductive) resistance, mirror char- ges and mirror currents are induced in it such that the almost relativistic flow is diverted sideways and reflected subsonic- ally, in a gyrating mode, observed as `knots´ and `head´. • The compression of the excess charges liberates the huge convected electric potential (between axis and periphery), of order e Φ = 10 19.5 eV √ L 44 , and a space-charge limited fall of the pair plasma through it converts its energy distri- bution into the observed broad power law.
SPECIAL SOURCE PROPERTIES • Head of jet propagates {super, sub} -sonically w.r.t. the CJM: Eilek type {A, B}, of {young, old} sources. • Multiple heads of stellar jet sources: not via re-starting, but via low-density shells of CJM. • QPO frequencies of the stellar-jet sources (micro quasars) have often small integer frequency ratios: reminiscent of stick-slip couplings of the corotating magnetosphere, interacting with the circumstellar disk; (remember Fourier transform of a sawtooth function).
Cen A Ø =0.48 Mpc (d/3Mpc) here: inner 10%
4‘ ≅ 20 kpc
3‘ ≅ 0.6 Mpc (d/0.6 Gpc)
3C 20
3C 438
3C 273 75 kpc / H -17.7
SUPERLUMINAL MOTIONS Galactic Extragalactic What is the nature of Discovery of two- sided moving jets One-sided moving jets ? Owen & Birretta (1999) Mirabel & Rodriguez (1994)
The Great Annihilator 1‘ ≅ 2 pc
d = 1 kpc , ∅ � 25“ � 0.2 lyr
Garden Sprinkler 1 lyr (d/5.8 kpc)
1.7‘ � 0.23 pc (d/0.46 kpc) HH 34
HH 30
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