Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way

Abstract

We report the detection of a variable point source, imaged at L'(3.8 microns) with the W. M. Keck II 10-meter telescope's adaptive optics system, that is coincident to within 18 mas of the Galaxy's central supermassive black hole and the unique radio source Sgr A*. While in 2002 this source (SgrA*-IR) was confused with the stellar source S0-2, in 2003 these two sources are separated by 87 mas allowing the new source's properties to be determined directly. On four separate nights, its observed L' magnitude ranges from 12.2 to 13.8, which corresponds to a flux density of 0.7 - 3 mJy, observed, and 4 - 17 mJy, dereddened; no other source in this region shows such large variations in flux density - a factor of 4 over a week and a factor of 2 over 40 min. In addition, it has a K-L' color greater than 2.1, which is at least 1 mag redder than any other source detected at L' in its vicinity. Based on this source's coincidence with the Galaxy's dynamical center, its lack of motion, its variability, and its red color, we conclude that it is associated with the central supermassive black hole. The short timescale for the 3.8 micron flux density variations implies that the emission arises in the accretion flow on physical size scales smaller than 5 AU, or 80 R_s for a 4x10^6 Mo black hole. We suggest that the 3.8 micron emission and the X-ray flares arise from the same underlying physical process, possibly the acceleration of a small populations of electrons to ultrarelativistic energies. In contrast to the X-ray flares which are only detectable 2% of the time, the 3.8 micron emission provides a new, constantly accessible, window into the physical conditions of the plasma in close proximity to the central black hole.

arXiv commentpublished in Astrophysical Journal Letters

References in corpus (23)

• Closest Star Seen Orbiting the Supermassive Black Hole at the Centre of the Milky Way
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth
• 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 Stellar Cusp Around the Supermassive Black Hole in the Galactic Center
• The Supermassive Black Hole at the Galactic Center
• Analysis of isoplanatic high resolution stellar fields by Starfinder code
• Stellar dynamics in the central arcsecond of our galaxy
• 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*
• The simultaneous spectrum of Sgr A* from 20cm to 1mm and the nature of the mm-excess
• On The Nature of the Variable Infrared Emission from Sgr A*
• 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
• An Accretion-Induced X-ray Flare in Sgr A*
• Radio Variability of Sagittarius A* - A 106 Day Cycle
• Mid-infrared imaging and spectroscopy of the enigmatic cocoon stars in the Quintuplet Cluster
• Limits on the Short Term Variability of Sagittarius A* in the Near-Infrared
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• Close stars and an inactive accretion disk in Sgr A*: Eclipses and flares
• Enhanced Microlensing by Stars Around the Black Hole in the Galactic Center
• Bright stars and an inactive disk in Sgr A* and other dormant galaxy centers. I. The optically thick disk

Cited by in corpus (203)

• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits
• Hot Accretion Flows Around Black Holes
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Stellar Orbits Around the Galactic Center Black Hole
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• SINFONI in the Galactic Center: young stars and IR flares in the central light month
• Noncommutative Black Holes, The Final Appeal To Quantum Gravity: A Review
• What Drives the Growth of Black Holes?
• On The Origin Of The Gamma Rays From The Galactic Center
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• Stellar Processes Near the Massive Black Hole in the Galactic Center
• The structure of the nuclear stellar cluster of the Milky Way
• Imaging Optically-Thin Hot Spots Near the Black Hole Horizon of Sgr A* at Radio and Near-Infrared Wavelengths
• The Submillimeter Bump in Sgr A* from Relativistic MHD Simulations
• An X-ray, IR, and Submillimeter Flare of Sagittarius A*
• Detection of the Intrinsic Size of Sagittarius A* through Closure Amplitude Imaging (includes Online Supporting Material)
• Polarimetry of near-infrared flares from Sagittarius A*
• Imaging Bright Spots in the Accretion Flow Near the Black Hole Horizon of Sgr A*
• On The Nature of the Variable Infrared Emission from Sgr A*
• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• TeV Gamma-Ray Observations of the Galactic Center
• First Simultaneous NIR/X-ray Detection of a Flare from SgrA*
• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• Analytic Kerr black hole lensing for equatorial observers in the strong deflection limit
• Constraints on a charge in the Reissner--Nordström metric for the black hole at the Galactic Center
• Methods for detecting flaring structures in Sagittarius A* with high frequency VLBI
• 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
• A Dynamical Model for Hot Gas in the Galactic Center
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• The Power of Imaging: Constraining the Plasma Properties of GRMHD Simulations using EHT Observations of Sgr A*
• Plasma diagnostic potential of 2p4f in N${}^{+}$ -- accurate wavelengths and oscillator strengths
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
• Spectrum and variability of the Galactic Center VHE gamma-ray source HESS J1745-290
• Sgr A* and General Relativity
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• Stellar Dynamics at the Galactic Center with an Extremely Large Telescope
• The two states of Sgr A* in the near-infrared: bright episodic flares on top of low-level continuous variability
• The First Laser Guide Star Adaptive Optics Observations of the Galactic Center: Sgr A*'s Infrared Color and the Extended Red Emission in its Vicinity
• Frequency-Dependent Shift in the Image Centroid of the Black Hole at the Galactic Center as a Test of General Relativity
• Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum. III. Quasi-Periodic Variability
• The Milky Way's Supermassive Black Hole: How good a case is it? A Challenge for Astrophysics & Philosophy of Science
• The Flare Activity of SgrA*; New Coordinated mm to X-Ray Observations
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Probing Post-Newtonian Gravity near the Galactic Black Hole with Stellar Doppler Measurements
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Mirages around Kerr black holes and retro-gravitational lenses
• 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
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• Source-intrinsic near-infrared properties of Sgr A*: Total intensity measurements
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Detection of Galactic Center source G2 at 3.8 $\mu$m during periapse passage
• Direct Measurements of Black Hole Charge with Future Astrometrical Missions
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Variations in the spectral slope of Sgr A* during a NIR flare
• Unprecedented variability of Sgr A* in NIR
• Tilted black hole accretion disc models of Sagittarius A*: time-variable millimetre to near-infrared emission
• 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
• Polarized NIR and X-ray Flares from SgrA*
• Prospects for testing the nature of Sgr A*'s NIR flares on the basis of current VLT- and future VLTI-observations
• Intra-day Variability of Sagittarius A* at 3 Millimeters
• An 8 hour characteristic time-scale in submillimetre light curves of Sagittarius A*
• Sgr A* flares: tidal disruption of asteroids and planets?
• Distinguishing black holes and wormholes with orbiting hot spots
• The mean infrared emission of SagittariusA*
• Traces of past activity in the Galactic Centre
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• The Submillimeter Polarization of Sgr A*
• Galactic Center Research: Manifestations of the Central Black Hole
• 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
• Constraining the range of Yukawa gravity interaction from S2 star orbits II: Bounds on graviton mass
• Dynamically important magnetic fields near the event horizon of Sgr A*
• A Persistent High-Energy Flux from the Heart of the Milky Way : Integral's view of the Galactic Center
• Is there a Supermassive Black Hole at the Center of the Milky Way?
• Stochastic Electron Acceleration During the NIR and X-ray Flares in Sagittarius A*
• A hidden friend for the galactic center black hole, Sgr A*
• Synchrotron Radiation From Radiatively Inefficient Accretion Flow Simulations: Applications to Sgr A*
• A 600 minute near-infrared lightcurve of Sagittarius A*
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• Challenges in Detecting Gamma-Rays From Dark Matter Annihilations in the Galactic Center
• Lensing By Sgr A* as a Probe of Modified Gravity
• Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations
• Stochastic Acceleration in the Galactic Center HESS Source
• The nucleus of NGC 253 and its massive stellar clusters at parsec scales
• Intra-Day Variation of Sagittarius A* at Short Millimeter Wavelengths
• Simultaneous Multi-Wavelength Observations of Sgr A*
• Constraints on tidal charge of the supermassive black hole at the Galactic Center with trajectories of bright stars
• Sgr A${}^{\ast }$: a laboratory to measure the central black hole and cluster parameters
• On the orientation of the Sagittarius A* system
• Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds
• Multiwavelength VLBI observations of Sagittarius A*
• Magnetic Jets from Swirling Disks
• Discovery of Substructure in the Scatter-Broadened Image of Sgr A*
• The circumstellar environment of T Tau S at high spatial and spectral resolution
• Direct Feeding of the Black Hole at the Galactic Center with Radial Gas Streams from Close-In Stellar Winds
• Modeling mm- to X-ray flare emission from SgrA*
• Gravitational Lensing of stars in the central arcsecond of our Galaxy
• Metrics and Motivations for Earth-Space VLBI: Time-Resolving Sgr A* with the Event Horizon Telescope
• A dual emission mechanism in Sgr A*/L' ?
• High Spectral Resolution Observations of the Massive Stars in the Galactic Center
• The pattern of accretion flow onto Sgr A*
• Effect of Electromagnetic Interaction on Galactic Center Flare Components
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Have Atmospheric Cerenkov Telescopes Observed Dark Matter?
• Simultaneous X-ray and Infrared Observations of Sagittarius A*'s Variability
• The extreme luminosity states of Sagittarius A*
• The Positron Puzzle
• Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*
• A Testable the Stochastic Acceleration Model for Flares in Sagittarius A*
• Large extra dimensions and small black holes at the LHC
• The Post-Periapse Evolution of Galactic Center Source G1: The second case of a resolved tidal interaction with a supermassive black hole
• Statistics of X-ray flares of Sagittarius A*: evidence for solar-like self-organized criticality phenomenon
• Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
• Detection of faint stars near SgrA* with GRAVITY
• Magnetic reconnection plasmoid model for Sagittarius A* flares
• Exploring plasma evolution during Sagittarius A* flares
• Reconnection-driven flares in 3D black hole magnetospheres -- A scenario for hot spots around Sagittarius A*
• Bright X-ray flares from Sgr A*
• Discovery of a Transient U-band Dropout in a Lyman-Break Survey: A Tidally-Disrupted Star at z = 3.3?
• Deep Images of the Galactic Center with GRAVITY
• Diffraction Limited Imaging Spectroscopy of the SgrA* Region using OSIRIS, a new Keck Instrument
• The Galactic Center: An Improved Astrometric Reference Frame for Stellar Orbits around the Supermassive Black Hole
• Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares
• From Multiwavelength to Mass Scaling: Accretion and Ejection in Microquasars and AGN
• Coordinated NIR/mm observations of flare emission from Sagittarius A*
• The black hole at the Galactic Center: observations and models
• A magnetohydrodynamic model for multi-wavelength flares from Sagittarius~A${}^{\star }$ (I): model and the near-infrared and X-ray flares
• On the possible sources of gravitational wave bursts detectable today
• The Galactic Center as a laboratory for theories of gravity and dark matter
• Unstable mass-outflows in geometrically thick accretion flows around black holes
• Low-mass companions to Hyades stars
• Gravitational lensing of stars orbiting the Massive Black Hole in the Galactic Center
• The Observed Galactic Annihilation Line. Possible Signature of the Cluster for Accreting Small Mass Black Holes
• Testing the nature of the supermassive black hole candidate in SgrA* with light curves and images of hot spots
• Detection of the Sgr A* activity at 3.8 and 4.8 microns with NACO
• A formal method for identifying distinct states of variability in time-varying sources: SgrA* as an example
• A Possible Model for the Long-Term Flares of Sgr A*
• Wisps in the Galactic center: NIR triggered observations of the radio source Sgr A* at 43 GHz
• A Deep Chandra View of A Candidate Parsec-Scale Jet from the Galactic Center Super-massive Black Hole
• Properties of the Radio-Emitting Gas Around SgrA*
• A Stability Timescale for Non-Hierarchical Three-Body Systems
• Performance of astrometric detection of a hotspot orbiting on the innermost stable circular orbit of the galactic centre black hole
• Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*
• Near-infrared polarimetry as a tool for testing properties of accreting super-massive black holes
• The millimetre variability of M81* -- Multi-epoch dual frequency mm-observations of the nucleus of M81
• A "coronal-mass-ejection'' model for flares in Sagittarius A*
• A consistency-test for determining whether ultra-compact dwarf galaxies could be the remnant nuclei of threshed galaxies
• Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
• Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations
• X-ray Scattering Halos from the Galactic Center: Implications for Diffuse Emission Around SgrA*
• Distinguishing an ejected blob from alternative flare models at the Galactic centre with GRAVITY
• Testing General Relativity with High-Resolution Imaging of Sgr A*
• Low angular momentum flow model for Sgr A*
• Multi-wavelength Variability of Sagittarius A* in July 2019
• Probing spacetime around Sagittarius A* using modeled VLBI closure phases
• Consistency of the Infrared Variability of Sgr A* over 22 years
• Black Holes Up Close
• Soft gamma-ray constraints on a bright flare from the Galactic Center supermassive black hole
• The Relationship Between Simulated Sub-Millimeter and Near-Infrared Images of Sagittarius A* from a Magnetically Arrested Black Hole Accretion Flow
• Testing a class of non-Kerr metrics with hot spots orbiting SgrA${}^{\ast }$
• The Swansong of the Galactic Center Source X7: An Extreme Example of Tidal Evolution near the Supermassive Black Hole
• The S2 star as a probe of the accretion disk of Sgr A*
• Low angular momentum flow model II for Sgr A*
• Fermi LAT observations of Sagittarius A*: Imaging Analysis
• Radiative shock oscillation model for the long-term flares of Sgr A*
• A Discovery of Rapid Optical Flares from Low-Luminosity Active Nuclei in Massive Galaxies
• Accretion models of Sgr A*
• Monitoring the Galactic Centre with Australia Telescope Compact Array
• Constraining the Cardoso-Pani-Rico metric with future observations of SgrA${}^{\ast }$
• Magnetically arrested disk flux eruption events to describe SgrA* flares
• Coordinated multi-wavelength observations of Sgr A*
• Science with the Keck Interferometer ASTRA Program
• Three-dimensional Radiative Properties of Hot Accretion Flows onto the Galactic Centre Black Hole
• Correlation between Flux and Spectral Index during Flares in Sagittarius A*
• A new line element derived from the variable rest mass in gravitational field
• Flare emission from Sagittarius A*
• Theory of disk accretion onto supermassive black holes
• New Evidence for a Flux-independent Spectral Index of Sgr A* in the Near-infrared
• Low angular momentum flow model of Sgr A* activity
• Coordinated mm/sub-mm observations of Sagittarius A* in May 2007
• A Pacemaker with P=2.48 hour Modulated the Generator of Flares in the X-ray Light Curve of Sgr A* in the year 2012
• Constraining cosmic-ray acceleration in the magnetospheric gaps of Sgr A*
• Non-thermal Synchrotron Emission and Polarization Signatures during Black Hole Flux Eruptions
• High Energy Activity of the Super-Massive Black Hole at the Galactic Center
• Gravitational wave scintillation by a stellar cluster
• Flares from Galactic centre pulsars: a new class of X-ray transients?
• Instruments on large optical telescopes -- A case study
• SgrA* emission at 7mm: variability and periodicity
• Flaring Activity of Sgr A*: Expanding Hot Blobs
• The Galactic Center with Roman
• Radio Emission from Sgr A*: Pulsar Transits Through the Accretion Disc
• Sagittarius A* near-infrared flares polarization as a probe of space-time I: Non-rotating exotic compact objects
• Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT
• Black Hole Survival Guide: Searching for Stars in the Galactic Center That Endure Partial Tidal Disruption
• High Energy Emission from the Galactic Center