Physical Conditions and Particle Acceleration in the Kiloparsec Jet of Centaurus A

Abstract

The non-thermal emission from the kiloparsec-scale jet of Centaurus A exhibits two notable features, bright diffuse emission and many compact knots, which have been intensively studied in X-ray and radio observations. H.E.S.S. recently reported that the very-high-energy gamma-ray emission from this object is extended along the jet direction beyond a kiloparsec from the core. Here, we combine these observations to constrain the physical conditions of the kpc-jet and study the origin of the non-thermal emission. We show that the diffuse jet is weakly magnetized (${\eta }_B\sim 10^{-2}$) and energetically dominated by thermal particles. We also show that knots are the sites of both amplified magnetic field and particle (re-)acceleration. To keep sufficient energy in thermal particles, the magnetic and non-thermal particle energy in the knot regions are tightly constrained. The most plausible condition is an energy equipartition between them, ${\eta }_B\sim {\eta }_e\sim 0.1$. Such weak magnetic energy implies that particles in the knots are in the slow cooling regime. We suggest that the entire kpc-scale diffuse emission could be powered by particles that are accelerated at and escaped from knots.

arXiv commentMain text 6 pages, 2 figures, accepted for publication in ApJ Letters

References in corpus (36)

• General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes
• General physical properties of bright Fermi blazars
• Constraints on the Physical Parameters of TeV Blazars
• The power of blazar jets
• Magnetic acceleration of relativistic AGN jets
• Relativistic Jets Shine through Shocks or Magnetic Reconnection?
• Minute-Timescale >100 MeV gamma-ray variability during the giant outburst of quasar 3C 279 observed by Fermi-LAT in 2015 June
• Radio and X-ray observations of the jet in Centaurus A
• The Distance to NGC 5128 (Centaurus A)
• Radiation Mechanisms and Physical Properties of GeV-TeV BL Lac Objects
• The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics
• Gamma-ray flares from red giant/jet interactions in AGN
• Chandra Observations of the X-ray Jet in Centaurus A
• The BL Lac heart of Centaurus A
• Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A
• Modelling TeV gamma-ray emission from the kiloparsec-scale jets of Centaurus A and M87
• Ten milliparsec-scale structure of the nucleus region in Centaurus A
• Interpretation of the flares of M87 at TeV energies in the cloud-jet interaction scenario
• Resolving acceleration to very high energies along the Jet of Centaurus A
• The X-ray Jet in Centaurus A: Clues on the Jet Structure and Particle Acceleration
• Long Term Monitoring of the Dynamics and Particle Acceleration of Knots in the Jet of Centaurus A
• The Hard X-ray Emission of Cen A
• The $\gamma$-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT
• The infrared jet in Centaurus A: multiwavelength constraints on emission mechanisms and particle acceleration
• Variability and Proper Motion of X-ray Knots in the Jet of Centaurus A
• Absorption of Nuclear Gamma-rays on the Starlight Radiation in FR I Sources: the Case of Centaurus A
• Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases For Low Luminosity BL Lacs
• Non-thermal radiation from collisions of compact objects with intermediate scale jets in active galaxies
• Collective non-thermal emission from an extragalactic jet interacting with stars
• Gamma rays from red giant wind bubbles entering the jets of elliptical host blazars
• Parsec-scale shocks in the kiloparsec-scale jet of Centaurus A
• Inverse Compton scattering of starlight in the kiloparsec-scale jet in Centaurus A: The origin of excess TeV $\gamma$-ray emission
• Knot in Cen A: Stochastic Magnetic Field for Diffusive Synchrotron Radiation?
• Inverse Compton Emission from Relativistic Jets in Binary Systems
• A 1D fluid model of the Centaurus A jet
• GeV-TeV gamma-rays produced by electrons in the kpc scale jet as a result of comptonization of the inner jet emission

Cited by in corpus (4)

• High energy emission component, population, and contribution to the extragalactic gamma-ray background of gamma-ray emitting radio galaxies
• Nuclear and electromagnetic cascades induced by ultrahigh-energy cosmic rays in radio galaxies: implications for Centaurus A
• Spatial variations of magnetic field along active galactic nuclei jets on sub-pc to Mpc scales
• The origin of the very-high-energy radiation along the jet of Centaurus A