The mean infrared emission of SagittariusA*

Abstract

(abridged) The massive black hole at the center of the Milky Way, SagittariusA* is, in relative terms, the weakest accreting black hole accessible to observations. At the moment, the mean SED of SgrA* is only known reliably in the radio to mm regimes. The goal of this paper is to provide constraints on the mean emission from SgrA* in the near-to-mid infrared. Excellent imaging quality was reached in the MIR by using speckle imaging combined with holographic image reconstruction, a novel technique for this kind of data. No counterpart of SgrA* is detected at 8.6 microns. At this wavelength, SgrA* is located atop a dust ridge, which considerably complicates the search for a potential point source. An observed 3 sigma upper limit of ~10 mJy is estimated for the emission of SgrA* at 8.6 microns, a tighter limit at this wavelength than in previous work. The de-reddened 3 sigma upper limit, including the uncertainty of the extinction correction, is ~84 mJy . Based on the available data, it is argued that, with currently available instruments, SgrA* cannot be detected in the MIR, not even during flares. At 4.8 and 3.8 microns, on the other hand, SgrA* is detected at all times, at least when considering timescales of a few up to 13 min. We derive well-defined time-averaged, de-reddened flux densities of 3.8+-1.3 mJy at 4.8 microns and 5.0+-0.6 mJy at 3.8 microns. Observations with NIRC2/Keck and NaCo/VLT from the literature provide good evidence that SgrA* also has a fairly well-defined de-reddened mean flux of 0.5-2.5 mJy at wavelengths of 2.1-2.2 microns. We present well-constrained anchor points for the SED of SgrA* on the high-frequency side of the Terahertz peak. The new data are in general agreement with published theoretical SEDs of the mean emission from SgrA*, but we expect them to have an appreciable impact on the model parameters in future theoretical work.

accepted for publication by Astronomy & Astrophysics on 20 June 2011

References in corpus (14)

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• Polarimetry of near-infrared flares from Sagittarius A*
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
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• Near-infrared polarimetry setting constraints on the orbiting spot model for Sgr A* flares
• Polarized NIR and X-ray Flares from SgrA*
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• Photometric Stellar Variability in the Galactic Center
• A 600 minute near-infrared lightcurve of Sagittarius A*
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Dusty Sources at the Galactic Center: The N- and Q-band view with VISIR
• Coordinated NIR/mm observations of flare emission from Sagittarius A*
• Near-infrared polarimetry as a tool for testing properties of accreting super-massive black holes

Cited by in corpus (54)

• Hot Accretion Flows Around Black Holes
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• The role of electron heating physics in images and variability of the Galactic Centre black hole Sagittarius A*
• The Disc-Jet Symbiosis Emerges: Modeling the Emission of Sagittarius A* with Electron Thermodynamics
• Physics of the Galactic Center Cloud G2, on its Way towards the Super-Massive Black Hole
• Sgr A* and General Relativity
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
• Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole
• Source-intrinsic near-infrared properties of Sgr A*: Total intensity measurements
• Tilted black hole accretion disc models of Sagittarius A*: time-variable millimetre to near-infrared emission
• GRMHD simulations of accretion onto Sgr A*: How important are radiative losses?
• Probing the magnetic field structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations
• A parameter survey of Sgr A* radiative models from GRMHD simulations with self-consistent electron heating
• Rapid Variability of Sgr A* across the Electromagnetic Spectrum
• Sgr A* X-ray flares from non-thermal particle acceleration in a magnetically arrested disc
• General relativistic MHD simulations of non-thermal flaring in Sagittarius A*
• The Galactic Center Weather Forecast
• The distribution of stars around the Milky Way's central black hole II: Diffuse light from sub-giants and dwarfs
• Holographic Imaging of Crowded Fields: High Angular Resolution Imaging with Excellent Quality at Very Low Cost
• ALMA Observations of the Terahertz Spectrum of Sagittarius A*
• Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*
• Spectral and Imaging properties of Sgr A* from High-Resolution 3D GRMHD Simulations with Radiative Cooling
• Spectral Energy Distribution of the inner accretion flow around Sgr A* -- Clue for a weak outflow in the innermost region
• The Post-Periapse Evolution of Galactic Center Source G1: The second case of a resolved tidal interaction with a supermassive black hole
• Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
• A Detection of Sgr A* in the far infrared
• Exploring plasma evolution during Sagittarius A* flares
• Towards Self-Consistent Modelling of the Sgr A* Accretion Flow: Linking Theory and Observation
• The impact of non-thermal electrons on event horizon scale images and spectra of Sgr A*
• Positron Effects on Polarized Images and Spectra from Jet and Accretion Flow Models of M87* and Sgr A*
• Probing spacetime and accretion model for the Galactic Center: Comparison of Kerr and dilaton black hole shadows
• Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*
• Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations
• A nonthermal bomb explains the near-infrared superflare of Sgr A*
• Consistency of the Infrared Variability of Sgr A* over 22 years
• Constraining the accretion flow density profile near Sgr A* using the $L^{\prime }$-band emission of the S2 star
• Sgr A* and its Environment: Low Mass Star Formation, the Origin of X-ray Gas and Collimated Outflow
• The Relationship Between Simulated Sub-Millimeter and Near-Infrared Images of Sagittarius A* from a Magnetically Arrested Black Hole Accretion Flow
• The Swansong of the Galactic Center Source X7: An Extreme Example of Tidal Evolution near the Supermassive Black Hole
• First observed interaction of the circumstellar envelope of an S-star with the environment of Sgr A*
• Galactic Centre star formation: the case of the missing gas disc
• Upper Limit on Brackett-gamma Emission from the Immediate Accretion Flow onto the Galactic Black Hole
• Effects of Hydrogen vs. Helium on Electromagnetic Black Hole Observables
• The Effects of Tilt on the Time Variability of Millimeter and Infrared Emission from Sagittarius A*
• Flare emission from Sagittarius A*
• Magnetic flux eruptions at the root of time-lags in low-luminosity AGN
• Candidate Young Stellar Objects in the S-cluster: The Kinematic Analysis of a Sub-population of the Low-mass G-objects close to Sgr A*
• Constraining cosmic-ray acceleration in the magnetospheric gaps of Sgr A*
• Mid-infrared extinction toward the Galactic center