The Section of Astrophysics, Astronomy and Mechanics of the Department of Physics of the National and Kapodistrian University of Athens in Greece offers a series of virtual Colloquia in Astrophysics, every Wednesday at 6pm EET.

The Spring Colloquium Sessions of the Astro UoA Colloquia begin on Wednesday 10/3. The first speaker is Prof Demosthenes Kazanas, who is going to present us the “AGN Warm Absorbers: The Rosetta Stone of AGN phenomenology?”.

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This event will happen on Wednesday, 10 March 2021 at 18:00 Athens time (UTC + 2:00) via the zoom platform. The zoom link is uploaded on the Colloquia website https://sites.google.com/view/astrouoaseminars/home

Abstract of the talk:
“Warm Absorbers are blue shifted absorption features in the AGN X-ray spectra, the result of outflows photoionized by the AGN continuum. They span a wide range of ionization parameter, a feature that allows one to estimate their density profiles along the observer’s line of sight. These are found to be quite shallow and extending over many decades in radius, inconsistent with radiation or thermally driven outflows, but consistent with magnetohydrodynamic ones launched across the entire accretion disk domain. It is shown that the corresponding wind mass flux increases with radius, a fact that affects crucially the dynamics of accretion. It is concluded that under these conditions, the global accretion rate is the parameter that determines the luminosity ratio of the Big Blue Bump to that of the hard X-ray emission, and as such determine the AGN structure in the black hole vicinity along with a host of phenomenology details. It is further proposed that similar structures are present in radio loud AGN too and they are crucial in the determination of their global phenomenology, usually referred to as the Blazar Sequence.”