Magnetization of Relativistic Current-Carrying Jets with Radial Velocity Shear

Abstract

Astrophysical jets, launched from the immediate vicinity of accreting black holes, carry away large amounts of power in a form of bulk kinetic energy of jet particles and electromagnetic flux. Here we consider a simple analytical model for relativistic jets at larger distances from their launching sites, assuming a cylindrical axisymmetric geometry with a radial velocity shear, and purely toroidal magnetic field. We argue that, as long as the jet plasma is in magnetohydrostatic equilibrium, such outflows tend to be particle dominated, i.e. the ratio of the electromagnetic to particle energy flux, integrated over the jet cross-sectional area, is typically below unity, $\sigma <1$. At the same time, for particular magnetic and radial velocity profiles, magnetic pressure may still dominate over particle pressure for certain ranges of the jet radius, i.e. the local jet plasma parameter ${\beta }_{pl}<1$, and this may be relevant in the context of particle acceleration and production of high-energy emission in such systems. The jet magnetization parameter can be elevated up to the modest values $\sigma \lesssim \mathcal{O}(10)$ only in the case of extreme gradients or discontinuities in the gaseous pressure, and a significantly suppressed velocity shear. Such configurations, which consist of a narrow, unmagnetized jet spine surrounded by an extended, force-free layer, may require an additional poloidal field component to stabilize them against current-driven oscillations, but even this will not elevate substantially their $\sigma$ parameter.

arXiv commentThe Astrophysical Journal, in press

References in corpus (24)

• Relativistic Reconnection: an Efficient Source of Non-Thermal Particles
• General physical properties of bright Fermi blazars
• Constraining Emission Models of Luminous Blazar Sources
• Particle acceleration at ultrarelativistic shocks: an eigenfunction method
• The extent of power-law energy spectra in collisionless relativistic magnetic reconnection in pair plasmas
• Non-thermal particle acceleration in collisionless relativistic electron-proton reconnection
• Asymptotic structure of Poynting dominated jets
• The role of kink instability in Poynting-flux dominated jets
• Are quasar jets dominated by Poynting flux?
• Radiation from the Relativistic Jet: a Role of the Shear Boundary Layer
• Accelerating AGN jets to parsec scales using general relativistic MHD simulations
• Transformation of the Poynting flux into the kinetic energy in relativistic jets
• Three-Dimensional Relativistic Magnetohydrodynamic Simulations of Current-Driven Instability. III. Rotating Relativistic Jets
• Relativistic Magnetic Reconnection in Electron-Positron-Proton Plasmas: Implications for Jets of Active Galactic Nuclei
• A powerful hydrodynamic booster for relativistic jets
• The internal structure of overpressured, magnetized, relativistic jets
• Time-Dependent Modeling of Gamma-ray Flares in Blazar PKS1510-089
• On the central core in MHD winds and jets
• The effect of poloidal velocity shear on the local development of current-driven instabilities
• Particle Acceleration during Magnetic Reconnection in a Low-beta Pair Plasma
• Observational Effects of Anomalous Boundary Layers in Relativistic Jets
• On the magnetisation and the radiative efficiency of BL Lac jets
• Internal instabilities in magnetized jets
• The influence of the magnetic field on the spectral properties of blazars