Search results for "Jets"
showing 10 items of 1074 documents
La musique dans et hors de la cathédrale : fête des fous et carnavals en Bourgogne à la fin du Moyen Age
2000
dir. Micheline Durand et Laura Weigert; International audience
La musique dans le Banquet du Faisan d'après Olivier de la Marche
2003
dir. Jean-Marie Cauchies; International audience
L'acceptation des dispositifs technologiquesd'auto-production par le consommateur : une approche par l'empowerment psychologique
2022
During the Covid-19 pandemic, the deployment of self-service technologies (self-checking, interactive terminals, smart devices…), allowing to substitute existing service employees and give more autonomy to consumers, have accelerated. In the french academic literature, Cova et al. (2013) conceptualized these devices as « directed self-production » technologies, underlining a more or less imposed transfer of tasks operated by firms. Among consumers, these technological devices have been subjected to ambivalent representations from consumers : some positive representations mainly related to greater autonomy for individuals exist alongside concerns about human contact degradation, macrostructu…
Stability of hydrodynamical relativistic planar jets : II. Long-term nonlinear evolution
2004
In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models undergoing qualitatively different non-linear evolution are clearly grouped in well-separated regions in a jet Lorentz factor/jet-to-ambient enthalpy diagram. Jets with a low Lorentz factor and small enthalpy ratio are disrupted by a strong shock after saturation. Those with a large Lorentz factor an…
Relativistic MHD simulations of extragalactic jets
2005
We have performed a comprehensive parameter study of the morphology and dynamics of axisymmetric, magnetized, relativistic jets by means of numerical simulations. The simulations have been performed with an upgraded version of the GENESIS code which is based on a second-order accurate finite volume method involving an approximate Riemann solver suitable for relativistic ideal magnetohydrodynamic flows, and a method of lines. Starting from pure hydrodynamic models we consider the effect of a magnetic field of increasing strength (up to β ≡ |b|2/2p ≈ 3.3 times the equipartition value) and different topology (purely toroidal or poloidal). We computed several series of models investigating the …
Instability of relativistic sheared jets and distinction between FRI and FRII sources
2002
We investigate the shear-driven instability of nonmagnetic relativistic jets with the bulk velocity, V , dependent on the cylindric radius, r. It is shown that instability can arise for any dependence of the velocity (or the Lorentz factor that is the same) on r. The shear-driven instability can e ectively operate in the whole volume of a jet. The growth time can be shorter than that of the Kelvin-Helmholtz instability. The considered instability leads to a turbulization of jets and can account for a distiction between the jets in the FRI and FRII sources. Urpin, V., Vadim.Urpin@uv.es
"Table 3" of "Energy dependence of event shapes and of alpha(s) at LEP-2."
1999
Moments of the Thrust Minor distributions at cm energies 133, 161, 172 and 183 GeV.
First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
2019
The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. To this end, we construct a large library of models based on general relativistic magnetohydrodynamic (GRMHD) simulations and synthetic images produced by general relativistic ray tracing. We compare the observed visibilities with this library and confirm that the asymmetric ring is consistent with earlier predictions of strong gravitational lensing of synchrotron emission from a hot plasma orbiting near the black hole event horizon. The ring rad…
Magnetized relativistic jets and helical magnetic fields
2021
This is the first of a series of two papers that deepen our understanding of the transversal structure and the properties of recollimation shocks of axisymmetric, relativistic, superfast magnetosonic, overpressured jets. They extend previous work that characterized these properties in connection with the dominant type of energy (internal, kinetic, or magnetic) in the jet to models with helical magnetic fields with larger magnetic pitch angles and force-free magnetic fields. In this paper, the magnetohydrodynamical models were computed following an approach that allows studying the structure of steady, axisymmetric, relativistic (magnetized) flows using one-dimensional time-dependent simulat…
Internal shocks in relativistic outflows: collisions of magnetized shells
2007
(Abridged): We study the collision of magnetized irregularities (shells) in relativistic outflows in order to explain the origin of the generic phenomenology observed in the non-thermal emission of both blazars and gamma-ray bursts. We focus on the influence of the magnetic field on the collision dynamics, and we further investigate how the properties of the observed radiation depend on the strength of the initial magnetic field and on the initial internal energy density of the flow. The collisions of magnetized shells and the radiation resulting from these collisions are calculated using the 1D relativistic magnetohydrodynamics code MRGENESIS. The interaction of the shells with the externa…