On the orientation of the Sagittarius A* system

Abstract

The near-infrared emission from the black hole at the Galactic center (Sgr A*) has unique properties. The most striking feature is a suggestive periodic sub-structure that has been observed in a couple of flares so far. Using near-infrared polarimetric observations and modelling the quasi-periodicity in terms of an orbiting blob, we try to constrain the three dimensional orientation of the Sgr A* system. We report on so far unpublished polarimetric data from 2003. They support the observations of a roughly constant mean polarization angle of 60 degr \pm 20 degr from 2004-2006. Prior investigations of the 2006 data are deepened. In particular, the blob model fits are evaluated such that constraints on the position angle of Sgr A* can be derived. Confidence contours in the position-inclination angle plane are derived. On a 3sigma level the position angle of the equatorial plane normal is in the range 60 degr - 108 degr (east of north) in combination with a large inclination angle. This agrees well with recent independent work in which radio spectral/morphological properties of Sgr A* and X-ray observations, respectively, have been used. However, the quality of the presently available data and the uncertainties in our model bring some ambiguity to our conclusions.

10 pages, 4 figures; Research Note accepted by A&A for publication

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• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• Galactic Center Research: Manifestations of the Central Black Hole
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• Near infrared flares of Sagittarius A*: Importance of near infrared polarimetry
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• The Intrinsic Two-Dimensional Size of Sagittarius A*
• Modeling mm- to X-ray flare emission from SgrA*
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• Simultaneous X-ray and Infrared Observations of Sagittarius A*'s Variability
• The extreme luminosity states of Sagittarius A*
• Bright X-ray flares from Sgr A*
• Testing the Accretion Flow with Plasma Wave Heating Mechanism for Sagittarius a* by the 1.3MM Vlbi Measurements
• Coordinated NIR/mm observations of flare emission from Sagittarius A*
• The long-term millimeter activity of active galactic nuclei
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• Coordinated multi-wavelength observations of Sgr A*
• Polarized signatures of adiabatically expanding hotspots in Sgr A*'s accretion flow
• Constraints on jet-driven disk accretion in Sagittarius A*
• Flare emission from Sagittarius A*
• Is it possible to measure the Lense-Thirring orbital shifts of the short-period S-star S4716 orbiting Sgr A${}^{\ast }$?
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• Nethotrons: exploring the possibility of measuring relativistic spin precessions, from Earth's satellites to the Galactic Centre