The stratified two-sided jet of Cygnus A. Acceleration and collimation

Abstract

High-resolution Very-Long-Baseline Interferometry observations of relativistic jets are essential to constrain fundamental parameters of jet formation models. At a distance of 249 Mpc, Cygnus A is a unique target for such studies, being the only Fanaroff-Riley Class II radio galaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing at millimeter wavelengths unveils those regions which appear self-absorbed at longer wavelengths and enables an extremely sharp view towards the nucleus to be obtained. We performed 7 mm Global VLBI observations, achieving ultra-high resolution imaging on scales down to 90 $\mu$as. This resolution corresponds to a linear scale of only $\sim$400 Schwarzschild radii (for $M_{\mathrm{BH}}=2.5\times 10^9{M}_{\odot }$). We studied the kinematic properties of the main emission features of the two-sided flow and probed its transverse structure through a pixel-based analysis. We suggest that a fast and a slow layer, with different acceleration gradients, exist in the flow. The extension of the acceleration region is large ($\sim 10^4{R}_{\mathrm{S}}$), indicating that the jet is magnetically-driven. The limb brightening of both jet and counter-jet and their large opening angles (${\varphi }_{\mathrm{J}}\sim 10^{\circ }$) strongly favor a spine-sheath structure. In the acceleration zone, the flow has a parabolic shape ($r\propto z^{0.55\pm 0.07}$). The acceleration gradients and the collimation profile are consistent with the expectations for a jet in "equilibrium'' (Lyubarsky 2009), achieved in the presence of a mild gradient of the external pressure ($p\propto z^{-k},k\le 2$).}

9 pages, 8 figures. Accepted for publication in Astronomy and Astrophysics

References in corpus (5)

• Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies
• Magnetic acceleration of relativistic AGN jets
• The Inner Jet of the Radio Galaxy M87
• GRMHD/RMHD Simulations and Stability of Magnetized Spine-Sheath Relativistic Jets
• A two-component jet model based on the Blandford-Znajek and Blandford-Payne processes

Cited by in corpus (68)

• MOJAVE - XIV. Shapes and opening angles of AGN jets
• The limb-brightened jet of M87 down to 7 Schwarzschild radii scale
• Event Horizon Telescope observations of the jet launching and collimation in Centaurus A
• A transition from parabolic to conical shape as a common effect in nearby AGN jets
• Reconnection-driven particle acceleration in relativistic shear flows
• Radio observations of active galactic nuclei with mm-VLBI
• Collimation, Acceleration and Recollimation Shock in the Jet of Gamma-Ray-emitting Radio-Loud Narrow-Line Seyfert 1 Galaxy 1H 0323+342
• Spatial growth of current-driven instability in relativistic rotating jets and the search for magnetic reconnection
• Kinematics of the M87 jet in the collimation zone: gradual acceleration and velocity stratification
• An Introduction to Particle Acceleration in Shearing Flows
• Jet collimation in NGC 315 and other nearby AGN
• How frequent are close supermassive binary black holes in powerful jet sources?
• Location of Gamma-ray emission and magnetic field strengths in OJ 287
• First 3 mm-VLBI imaging of the two-sided jet in Cygnus A. Zooming into the launching region
• Reconfinement and Loss of Stability in Jets from Active Galactic Nuclei
• The Cocoon Shocks of Cygnus A: Pressures and Their Implications for the Jets and Lobes
• Imaging Black Holes and Jets with a VLBI Array Including Multiple Space-Based Telescopes
• Jet collimation and acceleration in the giant radio galaxy NGC 315
• The Relativistic Jet Dichotomy and the End of the Blazar Sequence
• GR-MHD disk winds and jets from black holes and resistive accretion disks
• Structural Transition in the NGC 6251 Jet: An Interplay with the Supermassive Black Hole and Its Host Galaxy
• Particle Acceleration in Shearing Flows: Efficiencies and Limits
• Acceleration of Compact Radio Jets on Sub-parsec Scales
• Fast-spinning black holes inferred from symmetrically limb-brightened radio jets
• A spine-sheath model for strong-line blazars
• The Two-sided Jet Structures of NGC 1052 at Scales from 300 to $4\times 10^7$ Schwarzschild Radii
• Jets in radio galaxies and quasars: an observational perspective
• Rotation and toroidal magnetic field effects on the stability of two-component jets
• The TeV-emitting radio galaxy 3C 264. VLBI kinematics and SED modeling
• Particle acceleration in shearing flows: the self-generation of turbulent spine-sheath structures in relativistic MHD jet simulations
• A multiband study and exploration of the radio wave - $\gamma$-ray connection in 3C 84
• Ambilateral collimation study of the twin-jets in NGC1052
• Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A
• Synchrotron-Self-Compton radiation from magnetically-dominated turbulent plasmas in relativistic jets
• The jet collimation profile at high resolution in BL Lacertae
• Jet kinematics in the transversely stratified jet of 3C 84 A two-decade overview
• Derivation of the physical parameters of the jet in S5 0836+710 from stability analysis
• Particle acceleration in shearing flows: the case for large-scale jets
• Ejection of Double knots from the radio core of PKS 1510--089 during the strong gamma-ray flares in 2015
• Compact jets dominate the continuum emission in low-luminosity active galactic nuclei
• Shear Acceleration in Expanding Flows
• Production of intense episodic Alfvén pulses: GRMHD simulation of black hole accretion disks
• Bhjet: a public multi-zone, steady state jet + thermal corona spectral model
• Discovery of Limb Brightening in the Parsec-scale Jet of NGC 315 through Global Very Long Baseline Interferometry Observations and Its Implications for Jet Models
• On the maximum energy of non-thermal particles in the primary hotspot of Cygnus A
• Localizing the $\gamma$-ray emitting region in the blazar TXS 2013+370
• Observational Evidence to Support a Dense Ambient Medium Shaping the Jet in 3C 84
• The Kelvin-Helmholtz instability at the boundary of relativistic magnetized jets
• Active galactic nuclei imaging programs of the RadioAstron mission
• Jet Collimation and Acceleration in the Flat Spectrum Radio Quasar 1928+738
• Interactions between the jet and disk wind in a nearby radio intermediate quasar III Zw 2
• Detecting the Elusive Blazar Counter-Jets
• A Markov Chain Monte Carlo approach for measurement of jet precession in radio-loud active galactic nuclei
• MOJAVE -- XXII. Brightness temperature distributions and geometric profiles along parsec-scale AGN jets
• Parabolic jet shape on parsec scales in high redshift AGN
• Two-dimensional Particle-in-Cell simulations of axisymmetric black hole magnetospheres: angular dependence of the Blandford-Znajek flux
• The X-Ray Cavity Around Hotspot E in Cygnus A: Tunneled by a Deflected Jet
• First VLBI detection of Fornax A
• Toy model for the acceleration of blazar jets
• Conditions for Relativistic Magnetic Reconnection under the Presence of Shear Flow and Guide Field
• Jet formation studies in AGN: a search for new targets
• Analysis of Jet Dynamics and Collimation Characteristics of 0241+622 on Parsec Scales
• An adaptive mesh, GPU-accelerated, and error minimized special relativistic hydrodynamics code
• Fast algorithms to approximate the position-dependent point spread function responses in radio interferometric wide-field imaging
• VLBI Monitoring of the Sub-parsec-scale Jet in the Radio Galaxy 3C 66B at 22 GHz
• The twin-jet system in the FRII radio galaxy 3C 452: A sub-parsec scale VLBI study
• Identifying changing jets through their radio variability
• A revised view of the linear polarization in the subparsec core of M87 at 7 mm