Quasi-Static Model of Magnetically Collimated Jets and Radio Lobes. Ii. Jet Structure and Stability

Abstract

This is the second in a series of companion papers showing that when an efficient dynamo can be maintained by accretion disks around supermassive black holes in active galactic nuclei, it can lead to the formation of a powerful, magnetically driven, and mediated helix that could explain both the observed radio jet/lobe structures and ultimately the enormous power inferred from the observed ultrahigh-energy cosmic rays. In the first paper, we showed self-consistently that minimizing viscous dissipation in the disk naturally leads to jets of maximum power with boundary conditions known to yield jets as a low-density, magnetically collimated tower, consistent with observational constraints of wire-like currents at distances far from the black hole. In this paper we show that these magnetic towers remain collimated as they grow in length at nonrelativistic velocities. Differences with relativistic jet models are explained by three-dimensional magnetic structures derived from a detailed examination of stability properties of the tower model, including a broad diffuse pinch with current profiles predicted by a detailed jet solution outside the collimated central column treated as an electric circuit. We justify our model in part by the derived jet dimensions in reasonable agreement with observations. Using these jet properties, we also discuss the implications for relativistic particle acceleration in nonrelativistically moving jets. The appendices justify the low jet densities yielding our results and speculate how to reconcile our nonrelativistic treatment with general relativistic MHD simulations.

A Quasi-static Hyper-resistive Model of Ultra-high-energy Cosmic-ray Acceleration by Magnetically Collimated Jets Created by Active Galactic Nuclei

“…We begin with a review of our disk/jet model in Colgate, et al (2014)-hereafter Paper I-and jet structure and stability in Colgate, et al (2015)-hereafter Paper II.…”

Speculations about plasma free energy, 50 years later

“…I used my free energy method to estimate transport in a recent paper on properties of an astrophysical jet modelled as a magnetically collimated ‘screw-pinch’ carrying current (Colgate et al. 2015). These jets are observed by the synchrotron radiation they emit as a consequence of electron acceleration, taken here to be due to MHD kink modes in the pinch.…”

“…Then the voltage drop along a jet of length is given by using the total voltage and derived in Colgate et al. (2015). Thus only 1 % of the jet power is utilized in accelerating both ions and electrons, or 0.5 % into the electrons.…”

Jet in jet in M87

“…An interest in theoretical studies of relativistic jets, arisen after the first pioneering works on the energy extraction from a black hole and the jet origin (Penrose 1969;Blandford 1976;Lovelace 1976;Blandford & Znajek 1977;Blandford & Payne 1982), is yet more growing nowadays because of the necessity ⋆ E-mail: sobyanin@lpi.ru to firmly establish the nature of the jet and the exact mechanism of its launching, collimation, stabilization and propagation in the external medium (Chiueh et al 1991;Appl & Camenzind 1993;Istomin & Pariev 1996;Fendt 1997;Lynden-Bell 2003;Beskin & Nokhrina 2009;Porth & Fendt 2010;Porth et al 2011;Cao 2012;Colgate et al 2015;Tchekhovskoy & Bromberg 2016;Feng et al 2016;Yang & Reynolds 2016;English et al 2016;Britzen et al 2017;Sobacchi et al 2017). For the same reason, a significant role is given to high-resolution observational research (Junor et al 1999;Kovalev et al 2007;Hada et al 2011Hada et al , 2012Hada et al , 2014Doeleman et al 2012;Akiyama et al 2015), which can clarify some key features of the internal jet structure.…”