Göttingen 2012 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 19: Hauptvorträge Relativistische Astrophysik

GR 19.1: Invited Talk

Friday, March 2, 2012, 11:00–11:45, ZHG 002

Accretion onto Sagittarius A* at the Center of the Milky Way — •Andreas Eckart — I. Physikalisches Institut, Universität zu Köln; Zuelpicher Str. 77; 50937 Köln

The super-massive 4 million solar mass black hole (SMBH) SgrA* shows flare emission from the millimeter to the X-ray domain. Near-infrared polarimetry shows signatures of strong gravity that are statistically significant against randomly polarized red noise. This allows us to derive spin and inclination information of the SMBH. A detailed analysis of the flares in the framework of a Synchrotron Self Compton (SSC) mechanism shows that a scenario in which the infrared flares are explained by synchrotron emission and the associated X-ray flares are produced via SSC emission can also explain the variability spectrum observed in the sub-millimeter radio domain. The light curves suggest in many cases that the mm flare emission follows the NIR emission with a delay of 1.5 - 2 hours indicating that adiabatic expansion of a plasma of relativistic electrons is at work. A detailed analysis of the infrared light curves allow us to address the accretion phenomenon in a statistical way. The analysis shows that the flare amplitudes are dominated by a single state power law. SgrA* also allows us to study the interaction of the SMBH with the immediate interstellar and gaseous environment of the central stellar cluster. It appears that through infrared imaging of the central few arcseconds one can study both inflow and outflow phenomena linked to the SgrA* black hole. SgrA* will also be compared to nuclei of nearby galaxies and to higher luminosity extragalactic active nuclei.