THE ASTROPHYSICAL JETS Wolfgang Kundt Washington, 27 July 2007 - - PowerPoint PPT Presentation

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

(102 γ 107).

• 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 {ExB-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 β β x B) · dx = 1012eV β-3 B6 dx6.5 .

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 Erad = Btor , j ≈ ρ c, rρ(r=0) ≠ 0, with equipartition

• f 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

• rder e Φ = 1019.5 eV √L44 , and a space-charge limited fall
• f 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

75 kpc / H-17.7

3C 273

SUPERLUMINAL MOTIONS

Extragalactic

What is the nature of One-sided moving jets ?

Owen & Birretta (1999)

Galactic

Discovery of two- sided moving jets

Mirabel & Rodriguez (1994)

1‘ ≅ 2 pc

The Great Annihilator

d = 1 kpc , ∅ 25“ 0.2 lyr

1 lyr (d/5.8 kpc)

Garden Sprinkler

HH 34

1.7‘ 0.23 pc (d/0.46 kpc)

HH 30