Dynamics Inside the Radio and X-ray Cluster Cavities of Cygnus A and Similar FRII Sources

Abstract

We describe approximate axisymmetric computations of the dynamical evolution of material inside radio lobes and X-ray cluster gas cavities in Fanaroff-Riley II sources such as Cygnus A. All energy is delivered by a jet to the lobe/cavity via a moving hotspot where jet energy dissipates in a reverse shock. Our calculations describe the evolution of hot plasma, cosmic rays (CRs) and toroidal magnetic fields flowing from the hotspot into the cavity. Many observed features are explained. Gas, CRs and field flow back along the cavity surface in a "boundary backflow" consistent with detailed FRII observations. Computed ages of backflowing CRs are consistent with observed radio-synchrotron age variations only if shear instabilities in the boundary backflow are damped and we assume this is done with viscosity of unknown origin. Magnetic fields estimated from synchrotron self-Compton (SSC) X-radiation observed near the hotspot evolve into radio lobe fields. Computed profiles of radio synchrotron lobe emission perpendicular to the jet are dramatically limb-brightened in excellent agreement with FRII observations although computed lobe fields exceed those observed. Strong winds flowing from hotspots naturally create kpc-sized spatial offsets between hotspot inverse Compton (IC-CMB) X-ray emission and radio synchrotron emission that peaks 1-2 kpc ahead where the field increases due to wind compression. In our computed version of Cygnus A, nonthermal X-ray emission increases from the hotspot (some IC-CMB, mostly SSC) toward the offset radio synchrotron peak (mostly SSC). A faint thermal jet along the symmetry axis may be responsible for redirecting the Cygnus A non-thermal jet.

24 pages, 10 figures, accepted by ApJ

References in corpus (18)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• The Cavity of Cygnus A
• The Fermi Bubbles. II. The Potential Roles of Viscosity and Cosmic Ray Diffusion in Jet Models
• Ram pressure stripping of disc galaxies orbiting in clusters. II. Galactic wakes
• A Chandra study of particle acceleration in the multiple hotspots of nearby radio galaxies
• A method of estimation of the dynamical age of FR II-type radio sources from multifrequency data
• Hydrodynamic Models of Radio Galaxy Morphology: Winged and X-shaped Sources
• A high resolution view of the jet termination shock in a hot spot of the nearby radio galaxy Pictor A: implications for X-ray models of radio galaxy hot spots
• Chandra Reveals Twin X-ray Jets in the Powerful FR-II Radio Galaxy 3C353
• Multiwavelength study of Cygnus A II. X-ray inverse-Compton emission from a relic counterjet and implications for jet duty-cycles
• Multi-epoch parsec-scale observations of the blazar PKS 1510-089
• Creation of the X-ray Cavity Jet and its Radio Lobe in M87/Virgo with Cosmic Rays; Relevance to Relic Radio Sources
• Interaction of Fanaroff-Riley class II radio jets with a randomly magnetised intra-cluster medium
• The luminous X-ray hotspot in 4C 74.26: synchrotron or inverse-Compton emission?
• Cosmic ray diffusion fronts in the Virgo cluster
• Self-consistent evolution of gas and cosmic rays in Cygnus A and similar FR II classic double radio sources
• Cosmic-ray acceleration in supernova shocks

Cited by in corpus (7)

• Ultra-high energy cosmic rays from shocks in the lobes of powerful radio galaxies
• The Cocoon Shocks of Cygnus A: Pressures and Their Implications for the Jets and Lobes
• High Radio Frequency Properties and Variability of Brightest Cluster Galaxies
• The geometry and origin of ultra-diffuse ghost galaxies
• On the Importance of Very-light Internally-subsonic AGN Jets in Radio-mode AGN Feedback
• The X-ray Ribs Within the Cocoon Shock of Cygnus A
• First Dynamic Computation of Synchrotron Emission from the Cygnus A Radio Cavity; Evidence for Electron Pair Plasma in Cavity