Volume 473, Number 3, October III 2007
|Page(s)||707 - 710|
|Published online||28 August 2007|
On the orientation of the Sagittarius A* system
I.Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany e-mail: firstname.lastname@example.org
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
3 Institut für Theoretische Physik und Astrophysik, Universität zu Kiel, 24098 Kiel, Germany
4 Steward Observatory, The University of Arizona, 933 N. Cherry Ave. Tucson, AZ 85721, USA
5 Astronomical Institute, Academy of Sciences, Boční II, 14131 Prague, Czech Republic
Accepted: 15 August 2007
Context.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.
Aims.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.
Methods.We report on so far unpublished polarimetric data from 2003. They support the observations of a roughly constant mean polarization angle of ~ ± 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.
Results.Confidence contours in the position – inclination angle plane are derived. On a level the position angle of the equatorial plane normal is in the range ~ (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.
Key words: black hole physics / infrared: general / accretion, accretion disks / Galaxy: center
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.