Effect of Interacting Rarefaction Waves on Relativistically Hot Jets

Abstract

The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in-situ energy conversion between thermal and bulk kinetic energies which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium, and follows a simple scaling relation ${\tau }_{\mathrm{oscillation}}\propto (P_{\mathrm{jet},0}/P_{\mathrm{amb},0}{)}^{1/2}$. It is confirmed from extended two-dimensional simulations that this radial oscillating motion in the one-dimensional system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. It is found that when the ambient medium has a power law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure $\lambda$ evolves according to a self-similar relation $\lambda \propto t^{\alpha /2}$ where $\alpha$ is the power-law index of the pressure distribution.

38 pages, 21 figures. Accepted for publication in ApJ

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• Two-dimensional Numerical Study for Rayleigh-Taylor and Richtmyer-Meshkov Instabilities in Relativistic Jets
• The internal structure of overpressured, magnetized, relativistic jets
• Photospheric Emission from Collapsar Jets in 3D Relativistic Hydrodynamics
• The photospheric origin of the Yonetoku relation in gamma-ray bursts
• Propagation, cocoon formation, and resultant destabilization of relativistic jets
• Linear Theory of the Rayleigh-Taylor Instability at a Discontinuous Surface of a Relativistic Flow
• Magnetic inhibition of the recollimation instability in relativistic jets
• Rayleigh-Taylor Instability in Two-Component Relativistic Jets
• Magnetohydrodynamic structure of a plasmoid in fast reconnection in low-beta plasmas: Shock-shock interactions
• Rarefaction acceleration in magnetized gamma-ray burst jets
• The polarization of the synchrotron radiation from a recollimated jet: application to high-energy BL Lacs
• Stationary Relativistic Jets