Special Seminars



"The Gravitational Wave Era : Peeling the onion layer by layer down to the event horizon"

Pau Amaro-Seoane (Max Planck Institute Gravitational Physics)

One of the most interesting sources of gravitational waves is the inspiral of compact objects on to a massive black hole (MBH), commonly referred to as an extreme-mass ratio inspiral. The small object, typically a stellar black hole, emits significant amounts of GW along each orbit in the detector bandwidth. On the other hand, recent observations of the Galactic center revealed a dearth of giant stars inside the inner parsec relative to the numbers theoretically expected for a fully relaxed stellar cusp. In this talk I will give a general overview on the relevance of astrophysics to general relativity in galactic nuclei and vice-versa.

Seminar will be held at 11:15 am, in the CAMK Lecture Theater


"First Statistical Tests for Clumpy-Torus Models: Constraints from RXTE monitoring of Seyfert AGN"

Alex Markowitz (University of California San Diego)

We present an analysis of multi-timescale variability in line of sight X-ray absorbing gas as a function of optical classification in AGN to derive the first statistical constraints for recent _clumpy_ absorbing torus models. Such models represent the paradigm shift away from a classical "solid donut" morphology. We use the vast archive of Rossi X-ray Timing Explorer multi-timescale monitoring of dozens of type I and Compton-thin type II Seyfert AGN to search for discrete absorption events due to clouds transiting the line of sight. Most of our detected clouds are Compton-thin and located in the outer BLR or inner dusty torus. We discuss the resulting implications for cloud distributions in the context of the clumpy-torus models. We present the density profiles of the highest-quality eclipse events. We discuss cloud sizes, stability, and radial distribution across a wide range of distances, and explore the exhibited range in density profiles for the highest-quality eclipse events, and we discuss possible connections to the mechanisms that form and launch clouds.

Lecture starts at 11:15 am, Copernicus Astronomical Center, Warsaw, Lecture Hall.