Sgr A* in context: daily flares as a probe of the fundamental X-ray emission process in accreting black holes

Abstract

Our central Galactic supermassive black hole, Sgr A*, exists mostly in a very stable, extremely low-luminosity (~10^{-9} L_Edd), thermal quiescent state, which is interrupted roughly daily by a brief, nonthermal X-ray flare. Because they are not accompanied by significant changes in the radio wavelengths, the flares make Sgr A* unusual in the context of black holes accreting at slightly higher rates. Those sources display a radio/X-ray luminosity correlation whose normalization scales with central mass, and that holds over orders of magnitude in accretion power. There is significant scatter in this correlation, due in part to measurement uncertainties and intrinsic variability. By studying the correlation in sources bracketing Sgr A* in radio luminosity and whose physical parameters are well measured, we can derive a statistical measure of this local scatter. We find that Sgr A* in quiescence and the lower intensity flares fall well below the correlation in X-ray luminosity. The brightest flares are consistent within the scatter, which may indicate an upper bound on the X-ray luminosity. This trend is suggestive of a state transition at the extreme low end of accretion activity, only above which the radio/X-ray correlation is tracked. This scenario is easily testable because it must fulfill three unique observational predictions: 1) As long as Sgr A* remains at its current radio luminosity, no X-ray flare will be seen which statistically exceeds the prediction of the correlation, 2) no source already on the correlation will be seen to flare in the X-rays similar to Sgr A* (i.e., without corresponding increases in the radio luminosity), and 3) sources below a critical accretion rate or luminosity will show similar flares as Sgr A*, on timescales appropriate to their masses.

arXiv comment4 pages, 2 color figures, uses emulateapj.sty and apjfonts.sty, ApJL, accepted

References in corpus (35)

• A fundamental plane of black hole activity
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• A Scheme to Unify Low-Power Accreting Black Holes - Jet-Dominated Accretion Flows and the Radio/X-Ray Correlation
• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth
• A universal radio/X-ray correlation in low/hard state black hole binaries
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• The Supermassive Black Hole at the Galactic Center
• A 4% Geometric Distance to the Galaxy NGC4258 from Orbital Motions in a Nuclear Gas Disk
• Radio / X-ray correlation in the low/hard state of GX 339--4
• The Spectral Energy Distributions of Low-Luminosity Active Galactic Nuclei
• The Non-Linear Dependence of Flux on Black Hole Mass and Accretion Rate in Core Dominated Jets
• Stellar dynamics in the central arcsecond of our galaxy
• Plasma Ejection from Magnetic Flares and the X-ray Spectrum of Cygnus X-1
• A Geometric Determination of the Distance to the Galactic Center
• The Association of Jet Production with Geometrically Thick Accretion Flows and Black Hole Rotation
• A Jet-ADAF model for Sgr A*
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• Exploring the Role of Jets in the Radio/X-ray Correlations of GX339-4
• The Nature of the 10 Kilosecond X-ray Flare in Sgr A*
• XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*
• Coronal outflow dominated accretion discs: a new possibility for low luminosity black holes?
• On The Nature of the Variable Infrared Emission from Sgr A*
• First Simultaneous NIR/X-ray Detection of a Flare from SgrA*
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton Photon Imaging Cameras
• The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz
• An Accretion-Induced X-ray Flare in Sgr A*
• Constraining X-ray Binary Jet Models via Reflection
• Accretion Disk Evolution With Wind Infall I. General Solution and Application to Sgr A*
• Detection of Circular Polarization in M81*
• A Radio Survey for Linear and Circular Polarization in Low Luminosity Active Galactic Nuclei
• X-ray emission line gas in the LINER galaxy M81
• Chandra X-ray Observations of NGC 4258: Iron Absorption Lines from the Nucleus
• X-ray Scattering Halos from the Galactic Center: Implications for Diffuse Emission Around SgrA*
• A cool disk in the Galactic Center?

Cited by in corpus (31)

• Going with the flow: can the base of jets subsume the role of compact accretion disk coronae?
• The Black Hole Accretion Code
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• The Fundamental Plane of Accretion Onto Black Holes with Dynamical Masses
• Refining the fundamental plane of accreting black holes
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• 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
• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Sgr A* flares: tidal disruption of asteroids and planets?
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• Magnetic reconnection and plasmoid formation in three-dimensional accretion flows around black holes
• General relativistic MHD simulations of non-thermal flaring in Sagittarius A*
• Collisionless accretion onto black holes: dynamics and flares
• Why the fundamental plane of black hole activity is not simply a distance driven artifact
• Modeling mm- to X-ray flare emission from SgrA*
• Constraints on Relativistic Jets in Quiescent Black Hole X-ray Binaries from Broadband Spectral Modeling
• Estimating the kinetic luminosity function of jets from Galactic X-ray binaries
• The extreme luminosity states of Sagittarius A*
• A Multiwavelength View of a Mass Outflow from the Galactic Center
• GRMHD Simulations and Modeling for Jet Formation and Acceleration Region in AGNs
• Fundamental Plane of Black Hole Activity in Quiescent Regime
• Exploring Accretion and Disk-Jet Connections in the LLAGN M81*
• From Multiwavelength to Mass Scaling: Accretion and Ejection in Microquasars and AGN
• Outflow-Dominated Emission from the Quiescent Massive Black Holes in NGC 4621 and NGC 4697
• A time-dependent jet model for the emission from Sagittarius A*
• Flare emission from Sagittarius A*
• The 3 Ms Chandra Campaign on Sgr A*: A Census of X-ray Flaring Activity from the Galactic Center