Polarimetry of near-infrared flares from Sagittarius A*

Abstract

Context: We report new polarization measurements of the variable near-infrared emission of the SgrA* counterpart associated with the massive 3--4 10^6 solar masses Black Hole at the Galactic Center. Aims: We investigate the physical processes responsible for the variable emission from SgrA*. Methods: The observations have been carried out using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope Results: We find that the variable NIR emission of SgrA* is highly polarized and consists of a contribution of a non- or weakly polarized main flare with highly polarized sub-flares. The flare activity shows a possible quasi-periodicity of 20+-3 minutes consistent with previous observations. Conclusions: The highly variable and polarized emission supports that the NIR emission is non-thermal. The observations can be interpreted in a jet or temporary disk model. In the disk model the quasi-periodic flux density variations can be explained due to spots on relativistic orbits around the central MBH. Alternative explanations for the high central mass concentration involving boson or fermion balls are increasingly unlikely.

19 pages, 14 figures; published in A&A

Cited by in corpus (22)

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• The structure of the nuclear stellar cluster of the Milky Way
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• 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*
• Near-infrared polarimetry setting constraints on the orbiting spot model for Sgr A* flares
• Tidal effects on small bodies by massive black holes
• Polarized NIR and X-ray Flares from SgrA*
• K-band polarimetry of an Sgr A* flare with a clear sub-flare structure
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• First proper motions of thin dust filaments at the Galactic Center
• A 600 minute near-infrared lightcurve of Sagittarius A*
• On the orientation of the Sagittarius A* system
• Polarised infrared emission from X-ray binary jets
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• The Variability of Polarized Radiation from Sgr A*
• Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
• The variability of Sagittarius A* at 3 millimeter
• Linearly and Circularly Polarized Emission in Sagittarius A*
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• Constraints on jet-driven disk accretion in Sagittarius A*