Modelling TeV gamma-ray emission from the kiloparsec-scale jets of Centaurus A and M87

TL;DR

This paper models TeV gamma-ray emission from the jets of Centaurus A and M87, exploring inverse-Compton scattering as a source and using a new numerical code to analyze jet physics and magnetic fields.

Contribution

It introduces a new numerical code for inverse-Compton calculations and applies it to constrain jet magnetic fields in Centaurus A using gamma-ray observations.

Findings

Existing gamma-ray flux constraints limit jet magnetic field strengths in Centaurus A.

The model suggests inverse-Compton scattering can explain TeV gamma-ray emission.

Prospects for future CTA observations to further constrain jet physics.

Abstract

The widespread detection of synchrotron X-ray emission from the jets of low-power, nearby radio galaxies implies the presence of electrons at and above TeV energies. In this paper we explore the possibility that the TeV gamma-rays detected from the radio galaxies Cen A and M87, which both have bright, well-studied X-ray jets, are produced at least in part by inverse-Compton scattering of various photon fields by the high-energy electrons responsible for the synchrotron X-rays on kiloparsec scales. We describe a new numerical code that we have developed to carry out inverse-Compton calculations taking account of all the relevant physics and using detailed models of the jets and the photon fields in which they are embedded, and show that existing constraints on the very high-energy (VHE) gamma-ray fluxes of these two objects already place significant constraints on the magnetic field strengths in the jet in Cen A. Finally, we discuss the prospects for constraints on radio galaxy jet physics that may be obtained from observations with the Cerenkov Telescope Array (CTA).