Proton Acceleration by Collisionless Shocks in Supermassive Black Hole Coronae: Implications for High-Energy Neutrinos

Abstract

Recent observations by the IceCube Neutrino Observatory have revealed a significant excess of high-energy neutrinos from nearby Seyfert galaxies, such as NGC~1068, without a corresponding flux of high-energy gamma-rays. This suggests that neutrinos are produced via hadronic interactions in a region opaque to gamma-rays, likely a hot corona surrounding the central supermassive black hole. However, the mechanism responsible for accelerating the parent protons to the required energies ($\sim 100$ TeV) remains an open question. In this study, we investigate diffusive shock acceleration (DSA) in active galactic nucleus (AGN) coronae using a suite of one-dimensional Particle-in-cell (PIC) simulations spanning a broad range of plasma parameters. We find that DSA is a robust and efficient mechanism for proton acceleration, consistently channeling approximately 10\% of the shock's kinetic energy into non-thermal ions, even for shocks with sonic Mach number as low as $M_s\approx 2$. In contrast, the efficiency of electron acceleration is highly variable and less efficient ($<1\%$) in our parameter survey. These findings provide strong, first-principles support for the hadronic models of neutrino production in AGN and offer quantitative constraints that can explain the observed gamma-ray deficit.

Accepted for publication in ApJ

References in corpus (41)

• Hot Accretion Flows Around Black Holes
• Energy spectra of gamma-rays, electrons and neutrinos produced at proton-proton interactions in the very high energy regime
• SMILEI: a collaborative, open-source, multi-purpose particle-in-cell code for plasma simulation
• Simulations of Ion Acceleration at Non-relativistic Shocks. I. Acceleration Efficiency
• Evidence for neutrino emission from the nearby active galaxy NGC 1068
• Energy spectra of gamma-rays, electrons and neutrinos produced at interactions of relativistic protons with low energy radiation
• Simultaneous Acceleration of Protons and Electrons at Nonrelativistic Quasiparallel Collisionless Shocks
• Hidden Cores of Active Galactic Nuclei as the Origin of Medium-Energy Neutrinos: Critical Tests with the MeV Gamma-Ray Connection
• Simulations of Ion Acceleration at Non-relativistic Shocks. II. Magnetic Field Amplification
• On the Origin of High Energy Neutrinos from NGC 1068: The Role of Non-Thermal Coronal Activity
• Thermal disequilibration of ions and electrons by collisionless plasma turbulence
• Kinetic simulations of mildly relativistic shocks I: particle acceleration in high Mach number shocks
• Hidden Hearts of Neutrino Active Galaxies
• Origin of Cosmic Rays
• On high-energy particles in accretion disk coronae of supermassive black holes: implications for MeV gamma rays and high-energy neutrinos from AGN cores
• Detection of Coronal Magnetic Activity in Nearby Active Supermassive Black Holes
• Electron Preacceleration in Weak Quasi-perpendicular Shocks in High-beta Intracluster Medium
• Proton Acceleration in Weak Quasi-parallel Intracluster Shocks: Injection and Early Acceleration
• TeV neutrinos and hard X-rays from relativistic reconnection in the corona of NGC 1068
• A critical shock Mach number for particle acceleration in the absence of pre-existing cosmic rays: $M=\sqrt{5}$
• dHybridR: a Hybrid--Particle-in-Cell Code Including Relativistic Ion Dynamics
• A magnetized strongly turbulent corona as the source of neutrinos from NGC 1068
• Revealing the Production Mechanism of High-Energy Neutrinos from NGC 1068
• The Interplay between accelerated Protons, X-rays and Neutrinos in the Corona of NGC 1068: Constraints from Kinetic Plasma Simulations
• Particle acceleration and wave excitation in quasi-parallel high-Mach-number collisionless shocks: Particle-in-cell simulation
• Particle-in-cell simulations of particle energization from low Mach number fast mode shocks
• Neutrino and pair creation in reconnection-powered coronae of accreting black holes
• Neutrinos from stochastic acceleration in black hole environments
• Radiative Spectra from Disk Corona and Inner Hot Flow in Black Hole X-ray Binaries
• Radiation from the impact of broad-line region clouds onto AGN accretion disks
• Evidence for a Spectral Break or Curvature in the Spectrum of Astrophysical Neutrinos from 5 TeV--10 PeV
• Joint ALMA/X-ray monitoring of the radio-quiet type 1 AGN IC 4329A
• The Centimeter to Submillimeter Broad Band Radio Spectrum of the Central Compact Component in A Nearby Type-II Seyfert Galaxy NGC 1068
• Millimeter emission from supermassive black hole coronae
• On the influence of supra-thermal particle acceleration on the morphology of low-Mach, high-$\beta$ shocks
• High-energy Emission from Turbulent Electron-ion Coronae of Accreting Black Holes
• ALMA observation of evolving magnetized corona in the radio-quiet changing-state AGN NGC 1566
• Magnetic Field Amplification and Particle Acceleration in Weakly Magnetized Trans-relativistic Electron-ion Shocks
• First-principles measurement of ion and electron energization in collisionless accretion flow
• Energy Dissipation in Strong Collisionless Shocks: The Crucial Role of Ion-to-Electron Scale Separation in Particle-in-Cell Simulations
• SLAMS-Propelled Electron Acceleration at High-Mach Number Astrophysical Shocks