Seminars take place in the lecture room of the Spořilov building (see contacts) unless noted otherwise.

Scheduled seminars

Extragalactic Astronomy from Space: past, present and future

Martin Ward

This will not be primarily an historical talk, although I will start by giving a few examples of some pioneering satellites which opened up new windows on the Universe in the ultraviolet, X-rays and infrared. I will then focus on some more recent space observatories for example, the Hubble Telescope, XMM-Newton, and Spitzer, and show how data from these have contributed to our understanding of Active Galaxies and Quasars. In the final part of my talk I will use the James Webb Space Telescope as one example of a “near future” mission that will dominate several areas of investigation.

Location: Sporilov, mistnot 101

Title Evidence for the change in coronal geometry with the X-ray flux from the X-ray reverberation lag spectral modelling of NGC 4593

Mayukh Pahari

One important technique to understand the inner disc-corona geometry in accreting black hole systems is to measurement and model the Fourier frequency and energy-dependent X-ray reverberation delay spectra where the soft, reprocessed emission from the inner accretion disc is delayed with respect to the direct hard X-ray flashes from the corona. Such a modelling, based on simplified assumptions, allows us the first time to answer: 'What happens to disc corona geometric configuration when the primary X-ray flux changes?' In this talk, I will present results from the reverberation delay analysis of a variable, bright Seyfert 1 galaxy NGC 4593. Using the reverberation delay modelling technique on different observations where the X-ray flux changes by a factor of ~2-3, we observe that the model-predicted coronal size changes significantly. Such an effort will allow us to constrain the disc corona interactions as a response to the changing X-ray flux.

Location: Sporilov, mistnost 101

If you would like to give a seminar, please contact Georgios Loukes-Gerakopoulos or Vladimír Karas.