Wind-type flows in astrophysical jets. I. The initial relativistic acceleration

Journal Article · Mon Jul 15 00:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163307· OSTI ID:5373073

Ferrari, A; Trussoni, E; Rosner, R; Tsinganos, K

We present transonic wind-type solutions of the relativistic quasi--two-dimensional Navier-Stokes fluid equations, which we assume to govern the initial acceleration of the plasma in astrophysical jets emerging from the funnel of an accretion disk orbiting a compact central object. The solutions depend on geometrical parameters characterizing the shape and height of the accretion funnel and on radiation parameters characterizing the luminosity and collimation of the radiation field inside this funnel. The two major results of our study are, first, that rapid expansion of the gas at the exit of the accretion funnel, which interacts synergistically with momentum deposition by radiation pressure, can lead to multiple critical points in the flow and to supersonic speeds very close to the central object; this main feature of our solution is consistent with observations that jets might already be accelerated to relativistic speeds on the sub--0.1 pc distance scale. Second, we show that for suitable values of the parameters characterizing the shape of the accretion funnel and its associated radiation field, multiple transonic solutions for the same initial conditions of the bulk flow speed are obtained, with shock transitions connecting some of these transonic solutions. Because of the sensitivity of the flow to slight variations of the disk and radiation parameters, such discontinuous transitions between distinct transonic flows might be related to the observed phenomenology and variability of active galactic nuclei.

• Research Organization: Instituto di Fisica Generale dell'Universita; and Instituto di Cosmo-geofisica del Consiglio Nazionale delle Ricerche, Torino, Italy
• OSTI ID: 5373073
• Journal Information: Astrophys. J.; (United States), Vol. 294:2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GALAXIES
PLASMA JETS
NAVIER-STOKES EQUATIONS
ANALYTICAL SOLUTION
GENERAL RELATIVITY THEORY
PLASMA ACCELERATION
ACCRETION DISKS
COSMIC GASES
EQUATIONS OF MOTION
GALAXY NUCLEI
MORPHOLOGY
SCHWARZSCHILD METRIC
SHOCK WAVES
SUPERSONIC FLOW
ACCELERATION
DIFFERENTIAL EQUATIONS
EQUATIONS
FIELD THEORIES
FLUID FLOW
FLUIDS
GASES
METRICS
PARTIAL DIFFERENTIAL EQUATIONS
640105* - Astrophysics & Cosmology- Galaxies
657003 - Theoretical & Mathematical Physics- Relativity & Gravitation