Coordinated Multi-Wavelength Observations of Variable Emission from the Galactic Center

Eckart, A.; Zamaninasab, M.; Sabha, N.; García-Marín, M.; Kunneriath, D.; Straubmeier, C.; Muzic, K.; Witzel, G.; Bremer, M.; Valencia-Schneider, M.; Karas, V.; Dovciak, M.; Morris, M. R.; Baganoff, F.; Schödel, R.; Moultaka, J.; Buchholz, R. M.; Duschl, W.; Zensus, A.
The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies. Proceedings of a workshop held at Shanghai, China on October 19-23, 2009. Edited by Mark R. Morris, Q. Daniel Wang, and Feng Yuan. San Francisco: Astronomical Society of the Pacific, 2011, p.294


We summarize the results of recent radio to X-ray observations of Sagittarius A* (Sgr A*) with an emphasis on the near-infrared wavelength domain. The goal of these coordinated multi-wavelength observations is to investigate the variable emission from Sgr A* in order to obtain a better understanding of the underlying physical processes in the accretion flow/outflow. In the NIR the variable emission of Sgr A* is polarized and shows flares (flux density maxima) with a high intensity contrast modulations. The observations can be interpreted in the framework of a model involving a temporary disk with a short jet. The NIR variations may contain a significant contribution from an underlying physical process that can statistically be described as red-noise. In an accretion disk model this contribution may be interpreted in the framework of a multi-component structure in a differentially rotating disk which is occasionally dominated by a single hot-spot.