An Accretion-Induced X-ray Flare in Sgr A*

Abstract

The recent detection of a three-hour X-ray flare from Sgr A* by Chandra provides very strong evidence for a compact emitting region near this supermassive black hole at the Galactic center. Sgr A*'s mm/sub-mm spectrum and polarimetric properties, and its quiescent-state X-ray flux density, are consistent with a model in which low angular momentum gas captured at large radii circularizes to form a hot, magnetized Keplerian flow within tens of Schwarzschild radii of the black hole's event horizon. In Sgr A*'s quiescent state, the X-ray emission appears to be produced by self-Comptonization (SSC) of the mm/sub-mm synchrotron photons emitted in this region. In this paper, we show that the prominent X-ray flare seen in Sgr A* may be due to a sudden enhancement of accretion through the circularized flow. Depending on whether the associated response of the anomalous viscosity is to increase or decrease in tandem with this additional injection of mass, the X-ray photons during the outburst may be produced either via thermal bremsstrahlung (if the viscosity decreases), or via SSC (if the viscosity increases). However, the latter predicts a softer X-ray spectrum than was seen by Chandra, so it appears that a bremsstrahlung origin for the X-ray outburst is favored. A strong correlation is expected between the mm/sub-mm and X-ray fluxes when the flare X-rays are produced by SSC, while the correlated variability is strongest between the sub-mm/far-IR and X-rays when bremsstrahlung emission is dominant during the flare. In addition, we shows that future coordinated multi-wavelength observations planned for the 2002 and 2003 cycles may be able to distinguish between the accretion and jet scenarios.

15 pages, 3 figures, To appear in ApJ Letter

References in corpus (11)

• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• The Supermassive Black Hole at the Galactic Center
• The Accelerations of Stars Orbiting the Milky Way's Central Black Hole
• The Nature of the 10 Kilosecond X-ray Flare in Sgr A*
• The simultaneous spectrum of Sgr A* from 20cm to 1mm and the nature of the mm-excess
• Hydrodynamical Accretion Onto Sgr A* From Distributed Point Sources
• Polarimetric Imaging of the Massive Black Hole at the Galactic Center
• The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz
• Polarized mm And sub-mm Emission From Sgr A* At The Galactic Center
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• A Magnetic Dynamo Origin For The Sub-mm Excess In Sgr A*

Cited by in corpus (65)

• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• The Stellar Cusp Around the Supermassive Black Hole in the Galactic Center
• What Drives the Growth of Black Holes?
• Stellar dynamics in the central arcsecond of our galaxy
• Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way
• XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• TeV Gamma-Ray Observations of the Galactic Center
• Chandra-HETGS Observations of the Brightest Flare Seen from Sgr A*
• 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
• X-ray flares reveal mass and angular momentum of the Galactic Center black hole
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• Variability of Sagittarius A* - Flares at 1 Millimeter
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton Photon Imaging Cameras
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• Precessing jet nozzle connecting to a spinning black hole in M87
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Near-infrared polarimetry setting constraints on the orbiting spot model for Sgr A* flares
• Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate
• Electron Acceleration around the Supermassive Black Hole at the Galactic Center
• Radiatively Inefficient Accretion Flow Models of Sgr A*
• A Possible Rossby Wave Instability Origin for the Flares in Sagittarius A*
• Thermal X-Ray Iron Line Emission from the Galactic Center Black Hole Sagittarius A*
• 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*
• Near infrared flares of Sagittarius A*: Importance of near infrared polarimetry
• Repeated X-ray Flaring Activity in Sagittarius A*
• X-ray flares from Sgr A*: star-disk interactions?
• Synchrotron Radiation From Radiatively Inefficient Accretion Flow Simulations: Applications to Sgr A*
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• Limits on the Short Term Variability of Sagittarius A* in the Near-Infrared
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• Spin-Induced Disk Precession in the Supermassive Black Hole at the Galactic Center
• MHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasi-Periodicity
• Chandra Spectral and Timing Analysis of Sgr A*'s Brightest X-ray Flares
• Direct Feeding of the Black Hole at the Galactic Center with Radial Gas Streams from Close-In Stellar Winds
• The pattern of accretion flow onto Sgr A*
• Simultaneous X-ray and Infrared Observations of Sagittarius A*'s Variability
• A Testable the Stochastic Acceleration Model for Flares in Sagittarius A*
• X-Ray Flares and Oscillations from the Black Hole Candidate X-Ray Transient XTE J1650-500 at Low Luminosity
• A Radio Outburst Nearly Coincident with the Large X-ray Flare from Sgr A* on 2002-10-03
• Testing RIAF model for Sgr A* using the size measurements
• Sgr A* in context: daily flares as a probe of the fundamental X-ray emission process in accreting black holes
• An Inverse Compton Scattering Origin of X-ray Flares from Sgr A*
• A relativistic helical jet in the gamma-ray AGN 1156+295
• A Systematic Chandra study of Sgr A${}^{\star }$: I. X-ray flare detection
• A magnetohydrodynamic model for multi-wavelength flares from Sagittarius~A${}^{\star }$ (I): model and the near-infrared and X-ray flares
• A time-dependent jet model for the emission from Sagittarius A*
• X-ray Scattering Halos from the Galactic Center: Implications for Diffuse Emission Around SgrA*
• A Single Intrinsic Luminosity Function for Both Type-I and Type-II Active Galactic Nuclei
• 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
• A Systematic Chandra study of Sgr A${}^{\star }$: II. X-ray flare statistics
• Soft gamma-ray constraints on a bright flare from the Galactic Center supermassive black hole
• Monitoring the Galactic Centre with Australia Telescope Compact Array
• A Swift study of long-term changes in the X-ray flaring properties of Sagittarius A*
• Spin-Induced Disk Precession in Sagittarius A*
• Modulated X-ray Emissivity near the Stress Edge in Sgr A*
• Correlation between Flux and Spectral Index during Flares in Sagittarius A*
• Low angular momentum flow model of Sgr A* activity
• High Energy Activity of the Super-Massive Black Hole at the Galactic Center
• Radio Variability of the Sagittarius ${\mathrm{A}}^{\ast }$ due to an Orbiting Star
• A Relativistic Disk in Sagittarius A*
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton
• High Energy Emission from the Galactic Center