Detection of the Sgr A* activity at 3.8 and 4.8 microns with NACO

Abstract

L'-band (lambda=3.8 microns) and M'-band (lambda=4.8 microns) observations of the Galactic Center region, performed in 2003 at VLT (ESO) with the adaptive optics imager NACO, have lead to the detection of an infrared counterpart of the radio source Sgr A* at both wavelengths. The measured fluxes confirm that the Sgr A* infrared spectrum is dominated by the synchrotron emission of nonthermal electrons. The infrared counterpart exhibits no significant short term variability but demonstrates flux variations on daily and yearly scales. The observed emission arises away from the position of the dynamical center of the S2 orbit and would then not originate from the closest regions of the black hole.

5 pages, 3 figures, accepted in Astronomy & Astrophysics

References in corpus (12)

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• A Jet-ADAF model for Sgr A*
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• First Simultaneous NIR/X-ray Detection of a Flare from SgrA*
• II. Accurate Positions and Proper Motions of Stellar SiO Masers near the Galactic Center
• X-ray flares from Sgr A*: star-disk interactions?
• The infrared L'-band view of the Galactic Center with NAOS-CONICA at VLT

Cited by in corpus (24)

• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Advection-Dominated Accretion and the Black Hole Event Horizon
• Stellar Processes Near the Massive Black Hole in the Galactic Center
• The structure of the nuclear stellar cluster of the Milky Way
• Galactic Centre stellar winds and Sgr A* accretion
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• On The Nature of the Compact Dark Mass at the Galactic Center
• Where are all the gravastars? Limits upon the gravastar model from accreting black holes
• The Galactic Center cloud G2 and its gas streamer
• The mean infrared emission of SagittariusA*
• A dual emission mechanism in Sgr A*/L' ?
• Dusty Sources at the Galactic Center: The N- and Q-band view with VISIR
• The Post-Pericenter Evolution of the Galactic Center Source G2
• The K-band Spectrum of The Hot Star in IRS~8: An Outsider in the Galactic Center?
• Supernova Kicks and Dynamics of Compact Remnants in the Galactic Centre
• Compact mid-IR sources east of galactic center source IRS5
• Properties of bow-shock sources at the Galactic center
• Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• A Swift study of long-term changes in the X-ray flaring properties of Sagittarius A*
• 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*
• 3D AMR hydrosimulations of a compact source scenario for the Galactic Centre cloud G2