A two-fluid model for black-hole accretion flows: Particle acceleration, outflows, and TeV emission

Abstract

The multi-wavelength spectrum observed from M87 extends from radio wavelengths up to TeV gamma-ray energies. The radio through GeV components have been interpreted successfully using SSC models based on misaligned blazar jets, but the origin of the intense TeV emission detected during flares in 2004, 2005, and 2010 remains puzzling. It has been previously suggested that the TeV flares are produced when a relativistic proton jet originating in the core of M87 collides with a molecular cloud (or stellar atmosphere) located less than one parsec from the central black hole. We explore this scenario in detail here using a self-consistent model for the acceleration of relativistic protons in a shocked, two-fluid ADAF accretion disc. The relativistic protons accelerated in the disc escape to power the observed jet outflows. The distribution function for the jet protons is used to compute the TeV emission produced when the jet collides with a cloud or stellar atmosphere. The simulated broadband radiation spectrum includes radio, X-ray, and GeV components generated via synchrotron, as well as TeV emission generated via the production and decay of muons, positrons, and electrons. The self-consistency of the model is verified by computing the relativistic particle pressure using the distribution function, and comparing it with the relativistic particle pressure obtained from the hydrodynamical model. We demonstrate that the model is able to reproduce the multi-wavelength spectrum from M87 observed by VERITAS and HESS during the high-energy flares in 2004, 2005, and 2010.

27 pages, 9 figures

References in corpus (14)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• Fast variability of TeV gamma-rays from the radio galaxy M 87
• Synchrotron Self-Compton Analysis of TeV X-ray Selected BL Lacertae Objects
• Spine-sheath layer radiative interplay in subparsec-scale jets and the TeV emission from M87
• Faraday rotation in the jet of M87 inside the Bondi radius: indication of winds from hot accretion flows confining the relativistic jet
• A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the radiogalaxy M87
• Dynamical Structure of Viscous Accretion Disks with Shocks
• Shocks in relativistic viscous accretion flows around Kerr black holes
• Shocks in relativistic transverse stratified jets, a new paradigm for radio-loud AGN
• Radiation and Polarization Signatures of 3D Multi-zone Time-dependent Hadronic Blazar Model
• Neutrino, $\gamma$-ray and cosmic ray fluxes from the core of the closest radio galaxies
• Electron Acceleration in Pulsar-Wind Termination Shocks: An Application to the Crab Nebula Gamma-Ray Flares
• A two-fluid model for black-hole accretion flows: particle acceleration and disc structure
• Self-similar solutions for finite size advection-dominated accretion flows