Electron Acceleration around the Supermassive Black Hole at the Galactic Center

Abstract

The recent detection of variable infrared emission from Sagittarius A*, combined with its previously observed flare activity in X-rays, provides compelling evidence that at least a portion of this object's emission is produced by nonthermal electrons. We show here that acceleration of electrons by plasma wave turbulence in hot gases near the black hole's event horizon can account both for Sagittarius A*'s mm and shorter wavelengths emission in the quiescent state, and for the infrared and X-ray flares, induced either via an enhancement of the mass accretion rate onto the black hole or by a reorganization of the magnetic field coupled to the accretion gas. The acceleration model proposed here produces distinct flare spectra that may be compared with future coordinated multi-wavelength observations. We further suggest that the diffusion of high energy electrons away from the acceleration site toward larger radii might be able to account for the observed characteristics of Sagittarius A*'s emission at cm and longer wavelengths.

13 pages, 2 figures and 1 table, submitted to ApJL

References in corpus (6)

• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• Stochastic Acceleration of Electrons and Protons. I. Acceleration by Parallel Propagating Waves
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• Magnetically Driven Accretion Flows in the Kerr Metric II: Structure of the Magnetic Field
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Cited by in corpus (71)

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• Stochastic Acceleration by Turbulence
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
• A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission
• High energy gamma rays from the massive black hole in the Galactic Center
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• Time-Dependent Stochastic Particle Acceleration in Astrophysical Plasmas: Exact Solutions Including Momentum-Dependent Escape
• Time Dependent Models of Flares from Sagittarius A*
• Variations in the spectral slope of Sgr A* during a NIR flare
• Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate
• Sgr A* flares: tidal disruption of asteroids and planets?
• TeV Emission from the Galactic Center Black-Hole Plerion
• A Persistent High-Energy Flux from the Heart of the Milky Way : Integral's view of the Galactic Center
• Stochastic Electron Acceleration During the NIR and X-ray Flares in Sagittarius A*
• Repeated X-ray Flaring Activity in Sagittarius A*
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• Stochastic Acceleration in the Galactic Center HESS Source
• The X-ray flaring properties of Sgr A* during six years of monitoring with Swift
• MHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasi-Periodicity
• The Intrinsic Two-Dimensional Size of Sagittarius A*
• Chandra Spectral and Timing Analysis of Sgr A*'s Brightest X-ray Flares
• Acceleration and Escape Processes of High-energy Particles in Turbulence inside Hot Accretion Flows
• Particle acceleration in relativistic turbulence: A theoretical appraisal
• Particle acceleration in strong MHD turbulence
• Damping of MHD turbulence in Solar Flares
• The pattern of accretion flow onto Sgr A*
• Stochastic Particle Acceleration in Turbulence Generated by the Magnetorotational Instability
• Simultaneous X-ray and Infrared Observations of Sagittarius A*'s Variability
• A Testable the Stochastic Acceleration Model for Flares in Sagittarius A*
• Particle Acceleration by Fast Modes in Solar Flares
• Exploring plasma evolution during Sagittarius A* flares
• An Inverse Compton Scattering Origin of X-ray Flares from Sgr A*
• Diffraction Limited Imaging Spectroscopy of the SgrA* Region using OSIRIS, a new Keck Instrument
• Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares
• Modelling the black hole silhouette in Sgr A* with ion tori
• A Systematic Chandra study of Sgr A${}^{\star }$: I. X-ray flare detection
• The Galactic Center as a laboratory for theories of gravity and dark matter
• Polarized Emission of Sagittarius A*
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• Rapid Intrinsic Variability of Sgr A* at Radio Wavelengths
• The Observed Galactic Annihilation Line. Possible Signature of the Cluster for Accreting Small Mass Black Holes
• Ultra-High-Energy Cosmic Rays from the Radio Lobes of AGNs
• Nonlinear aspects of stochastic particle acceleration
• Diffuse TeV Emission at the Galactic Centre
• Distinguishing an ejected blob from alternative flare models at the Galactic centre with GRAVITY
• Multi-wavelength Variability of Sagittarius A* in July 2019
• No sign of G2's encounter affecting Sgr A*'s X-ray flaring rate from $Chandra$ observations
• Soft gamma-ray constraints on a bright flare from the Galactic Center supermassive black hole
• A new analytic solution for 2nd-order Fermi acceleration
• The Broadband Spectrum of Galaxy Clusters
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• A numerical study of the interplay between Fermi acceleration mechanisms in radio lobes of FR-II radio galaxies
• Neutrinos and Gamma Rays from Galaxy Clusters
• Modulated X-ray Emissivity near the Stress Edge in Sgr A*
• Disc-corona interaction in the heartbeat state of GRS 1915+105
• A Swift study of long-term changes in the X-ray flaring properties of Sagittarius A*
• Correlation between Flux and Spectral Index during Flares in Sagittarius A*
• Leaking Outside the Box: Kinetic Turbulence with Cosmic-Ray Escape
• New Evidence for a Flux-independent Spectral Index of Sgr A* in the Near-infrared
• Accretion in Strong Gravity: From Galactic to Supermassive Black Holes
• Constraining the Flaring Region of Sagittarius A* By 1.3mm VLBI Measurements
• High Energy Activity of the Super-Massive Black Hole at the Galactic Center
• Diagnostics of magnetohydrodynamic modes in the ISM through synchrotron polarization statistics
• Polarimetric Imaging of Sgr A* in its Flaring State
• Numerical modeling and physical interplay of stochastic turbulent acceleration for non-thermal emission processes