Inverse Compton scattering of starlight in the kiloparsec-scale jet in Centaurus A: The origin of excess TeV $\gamma$-ray emission

Abstract

Centaurus A (Cen~A) is the nearest active radio galaxy, which has kiloparsec (kpc) scale jets and {giant lobes detected by various instruments in radio and X-ray frequency ranges}. The $Fermi$--Large Area Telescope and High Energy Stereoscopic System (HESS) confirmed, that Cen~A is a very high-energy (VHE; $>0.1$~TeV) $\gamma$-ray emitter with a known spectral {softening} in the energy range from a few GeV to TeV. In this work, we consider a synchrotron self-Compton model in the nucleus for the broad band spectrum {below the break energy} and an external Compton model in kpc-scale jets for the $\gamma$-ray excess. Our results show that the observed $\gamma$-ray excess can be suitably described by the inverse Compton scattering of the starlight photons in the kpc-scale jets, which is consistent with the recent tentative report by the HESS on the spatial extension of the TeV emission along the jets. Considering the spectral fitting results, the excess can only be seen in Cen~A, which is probably due to two factors: (1) the host galaxy is approximately 50 times more luminous than other typical radio galaxies and (2) the core $\gamma$-ray spectrum quickly decays above a few MeV due to the low maximum electron Lorentz factor of ${\gamma }_{\mathrm{c}}=2.8\times 10^3$ resulting from the large magnetic field of 3.8~G in the core. By the comparison with other $\gamma$-ray detected radio galaxies, we found that the magnetic field strength of relativistic jets scales with the distance from the central black holes $d$ with $B(d)\propto d^{-0.88\pm 0.14}$.

arXiv comment9 pages, 4 figures

References in corpus (39)

• General Relativistic Magnetohydrodynamic Simulations of Jet Formation and Large-Scale Propagation from Black Hole Accretion Systems
• Canonical high power blazars
• The 1% Concordance Hubble Constant
• Magnetic acceleration of relativistic AGN jets
• The Structure of the M87 Jet: A Transition from Parabolic to Conical Streamlines
• Science with the Cherenkov Telescope Array
• The Jet-Disk Connection and Blazar Unification
• Radio and X-ray observations of the jet in Centaurus A
• Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets
• Fermi Discovery of Gamma-Ray Emission from NGC 1275
• Fermi Large Area Telescope Gamma-Ray Detection of the Radio Galaxy M87
• Inflation Physics from the Cosmic Microwave Background and Large Scale Structure
• Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars
• Dynamics and High Energy Emission of the Flaring HST-1 Knot in the M 87 Jet
• Fermi Large Area Telescope View of the Core of the Radio Galaxy Centaurus A
• A Study of High Energy Emission from the TeV blazar Mrk 501 during Multiwavelength Observations in 1996
• Innermost collimation structure of the M87 jet down to ~ten Schwarzschild radii
• The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics
• Chandra Observations of the X-ray Jet in Centaurus A
• Kinetic Luminosity and Composition of Active Galactic Nuclei Jets
• The host galaxy/AGN connection in nearby early-type galaxies. Is there a miniature radio-galaxy in every "core" galaxy?
• New results on particle acceleration in the Centaurus A jet and counterjet from a deep Chandra observation
• High Energy gamma-rays From FR I Jets
• 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
• The Suzaku Observation of the Nucleus of the Radio-Loud Active Galaxy Centaurus A: Constraints on Abundances of the Accreting Material
• 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
• Evidence for a second component in the high-energy core emission from Centaurus A?
• The $\gamma$-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT
• 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
• The nuclear SED of NGC6251: a BL Lac in the center of an FR I radio galaxy
• Suzaku view of X-ray Spectral Variability of the Radio Galaxy Centaurus A : Partial Covering Absorber, Reflector, and Possible Jet Component
• The origins of the gamma-ray flux variations of NGC 1275 based on 8 years of Fermi-LAT observations
• Discovery of a new extragalactic source population of energetic particles
• Modeling the Spectral Energy Distribution of the radio galaxy IC310
• Very high-energy gamma-ray signature of ultrahigh-energy cosmic-ray acceleration in Centaurus A
• 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 (15)

• Resolving acceleration to very high energies along the Jet of Centaurus A
• Multi-wavelength Emission from Galactic Jets: the Case of the Microquasar SS433
• Limits on X-ray Polarization at the Core of Centaurus A as Observed with the Imaging X-ray Polarimetry Explorer
• 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
• Circumnuclear Dust in AP Librae and the source of its VHE emission
• High-Energy Neutrino Emission from Espresso-Reaccelerated Ions in Jets of Active Galactic Nuclei
• Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model
• Spatial variations of magnetic field along active galactic nuclei jets on sub-pc to Mpc scales
• Physical Conditions and Particle Acceleration in the Kiloparsec Jet of Centaurus A
• Morphology of TeV gamma-ray emission from the kpc scale jets in radio galaxies
• The origin of the very-high-energy radiation along the jet of Centaurus A
• An Analysis of Soft X-ray Structures at Kiloparsec Distances from the Active Nucleus of Centaurus A Galaxy
• A pure hadronic model description of the observed neutrino emission from the tidal disruption event AT2019dsg
• Distributed accelerators in the jet of Centaurus A: the origin of the spectral hardening of very high energy gamma-rays