Poster abstract details
The Extreme Flux Density States of Sagittarius A*
Abstract
In order to investigate the low flux density states of SgrA* we use two independent methods to remove or strongly suppress the flux density contributions of stars in the central 2” diameter region around SgrA*. The two independent methods are a) low-pass filtering the image and b) identifying and removing the stars individually. As physical emission mechanisms for SgrA* we discuss bremsstrahlung, synchrotron and synchrotron self Compton emission and the thermal emission of an hypothetical optically thick disk.
For the lowest observed flux density sates both image reduction methods result in the detection of faint extended emission with a diameter of 0.5"-1.0" diameter and centered on the position of SgrA*. The luminosity during the low state can best be accounted for by synchrotron emission from a spotted accretion disk. For the high flux density state the Synchrotron Self Compton emission from THz peaked source components can fully account for the observed flux density variations observed in the NIR and X-ray domain. Further sensitive high angular resolution polarimetric NIR observations will help to distinguish between the importance of the different emission mechanisms in the low state of SgrA*.
For the lowest observed flux density sates both image reduction methods result in the detection of faint extended emission with a diameter of 0.5"-1.0" diameter and centered on the position of SgrA*. The luminosity during the low state can best be accounted for by synchrotron emission from a spotted accretion disk. For the high flux density state the Synchrotron Self Compton emission from THz peaked source components can fully account for the observed flux density variations observed in the NIR and X-ray domain. Further sensitive high angular resolution polarimetric NIR observations will help to distinguish between the importance of the different emission mechanisms in the low state of SgrA*.