Distributed accelerators in the jet of Centaurus A: the origin of the spectral hardening of very high energy gamma-rays

Abstract

We propose the synchrotron self-Compton (SSC) scenario coupled with filamentary jet model, to reproduce the very high energy $\gamma$-ray emissions from Cen A. With reference to self-similarity of knot-like features in the jet, we assume nonuniform magnetic field associated with current filaments having various transverse sizes. For energetic electron production, the diffusive shock acceleration at sites distributed over the kiloparsec-scale jet is considered. We show that maximum Lorentz factor of the electron steadily exceeds $10^8$ due to suppression of synchrotron loss of the electrons trapped in weak magnetic field of the thin filaments, and inhomogeneous SSC in the inner jet can dominantly contribute to establishment of the pronounced hardening of $\gamma$-ray flux detected by the H.E.S.S. It is also suggested that the spectral contribution from diffuse regions of the outer jet potentially amounts to the observed Fermi fluxes.

arXiv comment7 pages, 4 figures, accepted for publication in A&A

References in corpus (36)

• Interpenetrating plasma shells: near-equipartition magnetic field generation and non-thermal particle acceleration
• Radio and X-ray observations of the jet in Centaurus A
• The Distance to NGC 5128 (Centaurus A)
• Discovery of very high energy gamma-ray emission from Centaurus A with H.E.S.S
• Fermi Large Area Telescope View of the Core of the Radio Galaxy Centaurus A
• A wide and collimated radio jet in 3C 84 on the scale of a few hundred gravitational radii
• Chandra Observations of the X-ray Jet in Centaurus A
• Resolving the innermost parsec of Centaurus A at mid-infrared wavelengths
• The BL Lac heart of Centaurus A
• Progress in unveiling extreme particle acceleration in persistent astrophysical jets
• BAT X-ray Survey - III: X-ray Spectra and Statistical Properties
• Unveiling the Active Nucleus of Centaurus A
• A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the radiogalaxy M87
• Relativistic Collisionless Shocks in Unmagnetized Electron-Positron Plasmas
• The Suzaku Observation of the Nucleus of the Radio-Loud Active Galaxy Centaurus A: Constraints on Abundances of the Accreting Material
• Resolving acceleration to very high energies along the Jet of Centaurus A
• Eigenmodes and growth rates of relativistic current filamentation instability in a collisional plasma
• Particle Acceleration in Mildly Relativistic Shearing Flows: the Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets
• In-Situ Particle Acceleration in Extragalactic Radio Hot Spots: Observations Meet Expectations
• Filamentary structures as the origin of blazar jet radio variability
• 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
• Pair Plasma Dominance in the Parsec-Scale Relativistic Jet of 3C345
• Twelve and a Half Years of Observations of Centaurus A with RXTE
• Variability and Proper Motion of X-ray Knots in the Jet of Centaurus A
• Signatures of Relativistic Helical Motion in the Rotation Measures of AGN Jets
• One-zone SSC model for the core emission of Centaurus A revisited
• Self-Collimation and Magnetic Field Generation of Astrophysical Jets
• Discovery of Optical Emission in the Hotspots of Three 3CR Quasars: High-Energy Particle Acceleration in Powerful Radio Hotspots
• A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour
• Transitive X-ray spectrum and PeV gamma-ray cutoff in the M87 jet: Electron "Pevatron"
• Inverse Compton scattering of starlight in the kiloparsec-scale jet in Centaurus A: The origin of excess TeV $\gamma$-ray emission
• Ultrahigh-energy neutrinos as a probe of espresso-shear acceleration in jets of Centaurus A
• Effects of mirror reflection versus diffusion anisotropy on particle acceleration in oblique shocks
• Phase-transient hierarchical turbulence as an energy correlation generator of blazar light curves
• A Soft X-Ray Lag Detected in Centaurus A