Wednesday Colloquium

"Radio View of Black Holes Shadows"

Monika Mościbrodzka (Radboud University, The Netherlands)Show abstract

In the final lecture I will overview the black hole imaging using the Event Horizon Telescope. The lecture will discuss recent improvements of the telescope and it’s capability to test the Einstein Theory of Gravity and theory of accretion disks in the future.

"Dwarf Galaxies and the Black Hole Scaling Relations"

Andrew King (Department of Physics and Astronomy, University of Leicester)Show abstract

The masses of supermassive black holes correlate tightly with properties of their host galaxies. One theory of these scaling relations ascribes them to feedback from black hole accretion, while a completely different picture argues that they arise purely statistically as galaxies and their central black holes are assembled by repeated mergers. Recent observations extend one of these scalings (the M - sigma relation) to dwarf galaxies. I will argue that this allows a clear decision between the two alternative theories of the scaling relations.

"Cosmology and measurements of anisotropy of the cosmic microwave background; Satellite mission Planck – the beginning of the end, or the end of the beginning …"

Krzysztof Górski (Jet Propulsion Laboratory, Pasadena, CA)Show abstract

After over five years in flight, and the follow on period of science analysis, the satellite CMB mission Planck has been recently completed. I will present personal reminiscences of this remarkably successful effort, address the impact of its science results on modern cosmology, and comment on the future of space exploration of the cosmic microwave background.

Due to the time difference between Warsaw and Pasadena, the seminar will be held at 17:15 (local time in Warsaw). Informal gathering will start at 16:45.

"Episodic outflows from SANE discs"

Miljenko Cemeljic (CAMK, Warsaw)Show abstract

Episodic outflows from SANE discs Abstract: We investigate the episodic ejection of plasmoids from a hot accretion flow around a black hole. Based on full 3D numerical simulations with General Relativistic MHD code Athena++, described is formation and emergence of the flux ropes and their ejection into the disk corona. Loops of magnetic field form flux ropes, similar to the coronal mass ejections from the Sun. Material captured into such ropes is pushed outwards into corona in periodically repeating ejections. We find that reconnection layers below the flux ropes emerge with the same periodicity from the disk in our simulations as the flux ropes. Above the rope, another reconnection layer forms, which helps the launching into the corona. Application of our results to the case of Sgr A* gives the period of ejections of 6 hours, which matches the time-scale of the observed periodic flares.

"Constraining the geometry of the accretion flow in black hole X-ray binaries"

Marta Dziełak (CAMK, Warsaw)