Radiation from the impact of broad-line region clouds onto AGN accretion disks

Abstract

Active galactic nuclei are supermassive black holes surrounded by an accretion disk, two populations of clouds, bipolar jets, and a dusty torus. The clouds move in Keplerian orbits at high velocities. In particular, the broad-line region (BLR) clouds have velocities ranging from $1000$ to $10000$ km s${}^{-1}$. Given the extreme proximity of these clouds to the supermassive black hole, frequent collisions with the accretion disk should occur. The impact of BLR clouds onto the accretion disk can produce strong shock waves where particles might be accelerated. The goal of this work is to investigate the production of relativistic particles, and the associated non-thermal radiation in these events. In particular, we apply the model we develop to the Seyfert galaxy NGC 1068. We analyze the efficiency of diffusive shock acceleration in the shock of colliding clouds of the BLR with the accretion disk. We calculate the spectral energy distribution of photons generated by the relativistic particles and estimate the number of simultaneous impacts needed to explain the gamma radiation observed by the Fermi satellite in Seyfert galaxies. We find that is possible to understand the measured gamma emission in terms of the interaction of clouds with the disk if the hard X-ray emission of the source is at least obscured between $20\%$ and $40\%$. The total number of clouds contained in the BLR region might be between $3\times 10^8$ and $6\times 10^8$, which are values in good agreement with the observational evidence. The maximum energy achieved by the protons ($\sim$ PeV) in this context allows the production of neutrinos in the observing range of IceCube.

arXiv comment9 pages, 8 figures, 6 tables. Accepted for publication in A&A

References in corpus (41)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• Fermi Large Area Telescope Fourth Source Catalog
• Energy spectra of gamma-rays, electrons and neutrinos produced at proton-proton interactions in the very high energy regime
• Time-integrated Neutrino Source Searches with 10 years of IceCube Data
• Reverberation Mapping of High-Luminosity Quasars: First Results
• A massive binary black-hole system in OJ287 and a test of general relativity
• GeV Observations of Star-forming Galaxies with \textit{Fermi} LAT
• Keplerian Motion of Broad-Line Region Gas as Evidence for Supermassive Black Holes in Active Galactic Nuclei
• ALMA resolves the torus of NGC 1068: continuum and molecular line emission
• The Structure of the Broad Line Region in AGN: I. Reconstructed Velocity-Delay Maps
• The Parsec-scale Radio Structure of NGC 1068 and the Nature of the Nuclear Radio Source
• NuSTAR Spectroscopy of Multi-Component X-ray Reflection from NGC 1068
• Non-Keplerian rotation in the nucleus of NGC 1068: evidence for a massive accretion disk?
• On the Origin of High Energy Neutrinos from NGC 1068: The Role of Non-Thermal Coronal Activity
• NuSTAR catches the unveiling nucleus of NGC 1068
• On The Nature of Low Luminosity Narrow Line AGN
• Long-term variability of AGN at hard X-rays
• The Link Between the Hidden Broad Line Region and the Accretion Rate in Seyfert 2 Galaxies
• The Magnetohydrodynamics of Shock-Cloud Interaction in Three Dimensions
• Gamma rays from cloud penetration at the base of AGN jets
• Counter-Rotation and High Velocity Outflow in the Parsec-Scale Molecular Torus of NGC 1068
• Magnetar-energized supernova explosions and GRB-jets
• Active galactic nuclei at gamma-ray energies
• X-ray flares from Sgr A*: star-disk interactions?
• Massive protostars as gamma-ray sources
• Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars
• Galactic outflow driven by the active nucleus and the origin of the gamma-ray emission in NGC 1068
• Non-thermal processes around accreting galactic black holes
• BLR kinematics and Black Hole Mass in Markarian 6
• A critical shock Mach number for particle acceleration in the absence of pre-existing cosmic rays: $M=\sqrt{5}$
• Upholding the Unified Model for Active Galactic Nuclei: VLT/FORS2 Spectropolarimetry of Seyfert 2 galaxies
• Particle transport in magnetized media around black holes and associated radiation
• Gamma-ray opacity of the anisotropic stratified broad-line regions in blazars
• Red giant-disk encounters: Food for quasars?
• Unveiling the origin of the gamma-ray emission in NGC 1068 with the Cherenkov Telescope Array
• Gamma-ray absorption and the origin of the gamma-ray flare in Cygnus X-1
• Supersonic Collisions between Two Gas Streams
• Gamma-ray activity of Seyfert galaxies and constraints on hot accretion flows
• Gamma rays from jets interacting with BLR clouds in blazars
• High-energy radiation from collisions of high velocity clouds and the Galactic disk
• Numerical simulation of small perturbation on an accretion disk due to the collision of a star with the disk near the black hole

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• Broad-line Region Clouds orbiting an AGN sample
• Electromagnetic signatures of black hole clusters in the center of super-Eddington galaxies
• Modeling the Reverberation Response of the Broad Line Region in Active Galactic Nuclei II: Incorporating Photoionization Models
• Proton Acceleration by Collisionless Shocks in Supermassive Black Hole Coronae: Implications for High-Energy Neutrinos
• Metallicity Ceiling in Quasars from Recycled Stellar Winds
• Super-Accreting Active Galactic Nuclei as Neutrino Sources
• Resonant W and Z Boson Production in FSRQ Jets: Implications for Diffuse Neutrino Fluxes
• Non-thermal emission from fall-back clouds in the Broad-Line Region of Active Galactic Nuclei