Issue |
A&A
Volume 443, Number 3, December I 2005
|
|
---|---|---|
Page(s) | 863 - 881 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20053115 | |
Published online | 15 November 2005 |
Nonlinear stability of relativistic sheared planar jets
1
Departament d'Astronomia i Astrofísica, Universitat de València, 46100 Burjassot, Spain e-mail: perucho@mpifr-bonn.mpg.de, jose-maria.marti@uv.es
2
Toruń Centre for Astronomy, Nicholas Copernicus University, 97-148 Piwnice k.Torunia, Poland e-mail: mhanasz@astri.uni.torun.pl
Received:
22
March
2005
Accepted:
15
June
2005
The linear and non-linear stability of sheared, relativistic
planar jets is studied by means of linear stability analysis and
numerical hydrodynamical simulations. Our results extend the previous
Kelvin-Hemlholtz stability studies for relativistic, planar jets in
the vortex sheet approximation performed by Perucho et al. (2004a, A&A, 427, 415; 2004b, A&A, 427, 431)
by including a shear layer between the jet and the external medium and
more general perturbations. The models considered span a wide range of
Lorentz factors () and internal energies
(
) and are classified into three classes
according to the main characteristics of their long-term, non-linear
evolution. We observe a clear separation of these three groups in a
relativistic Mach-number Lorentz-factor plane. Jets with a low Lorentz
factor and small relativistic Mach number are disrupted after
saturation. Those with a large Lorentz factor and large relativistic
Mach number are the stablest, due to the appearance of short
wavelength resonant modes which generate local mixing and heating in
the shear layer around a fast, unmixed core, giving a plausible
solution for the problem of the long-term stability of relativistic
jets. A third group is present between them, including jets with
intermediate values of Lorentz factor and relativistic Mach number,
which are disrupted by a slow process of mixing favored by an
efficient and continuous conversion of kinetic into internal
energy. In the long term, all the models develop a distinct
transversal structure (shear/transition layers) as a consequence of KH
perturbation growth, depending on the class they belong to. The
properties of these shear layers are analyzed in connection with the
parameters of the original jet models.
Key words: galaxies: jets / hydrodynamics / instabilities
© ESO, 2005
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