CfA Colloquium Schedule Spring 2008
 14 February 2008

14 February 2008

Speaker: Bozena Czerny (Copernicus Astronomical Center, Warsaw)

Title: Active galactic nuclei: the weather report

Abstract:Accretion onto massive black holes in active galactic nuclei provides insights into a behavior of the material in the strong gravity field. However, active nuclei are enshrouded by the host galaxy material obscuring the direct view. In addition the same accretion process powers also an outflow, and inflow/outflow phenomena are strongly coupled. Both the outflowing material and the accreting one contribute to the observed variability, particularly in the X-ray band. These "weather-type" phenomena complicate analysis of the flow close to a black hole. They may as well provide a strong impact onto the host galaxy environment. I will summarize the current understanding of the galactic nuclear activity concentrating on radio-quiet sources, which generally allow for a better view of the most central regions, and stress the trends with the Eddington luminosity ratio that vary over several orders of magnitude between highly active quasars and weakly active low luminosity AGN.

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