Talks, Colloquia

5:00 pm Via Zoom, Registrierung , Otto-Haxel-Hörsaal
Prof. Dr. Sibylle Günter Max-Planck-Institut für Plasmaphysik Garching

Fusion – the way to a new primary energy source

Nuclear fusion could contribute to the energy mix in the second half of this century. For a fusion reactor, matter has to be heated up to extremely high temperatures: more than 100 million degrees - about a factor of 10 hotter than the sun's core. At these temperatures, the material is fully ionized. The charged particles can be confined by magnetic fields, which are also able to provide the required efficient heat insulation. There are two promising magnetic confinement concepts: tokamak and stellarator. The tokamak concept as realized in ITER is by far the most advanced confinement configuration. It however requires the continuous flow of an electric current in a donut-shaped plasma which hardly allows for steady state operation. An alternative to the tokamak is the stellarator, which has a considerably more complex magnetic configuration, but is intrinsically stationary. The complex magnetic field of a stellarator requires careful optimization to ensure sufficiently good confinement properties. The first optimized stellarator of sufficient size to proof that the stellarator concept has the potential for a power plant, Wendelstein 7-X, in 2015 has started operation in Greifswald, Germany. The optimization of the magnetic field structure has successfully been proven during the first experimental campaigns. The pros and cons of the two confinement concepts will be compared and the problems to be solved on the way to a fusion power plant will be discussed.

2:00 pm Online, SR 1.403
Prof. Dr. Artur Widera Fachbereich Physik, TU Kaiserslautern

Engineering single-atom devices in ultracold gases

4:00 pm Zoom, 973 7719 2005; please contact the host (Richard Tuffs, MPIK) for the meeting password
Dr. Dominika Wylezalek ZAH, University of Heidelberg

Tracing AGN feedback signatures from small to large scales across cosmic time

https://zoom.us/j/97377192005?pwd=OUZPR1Z3ZGc5WDZPYW1SakEzV1pvQT09 AGN feedback is now widely considered to be one of the main drivers in regulating the growth of massive galaxies. In my talk I will describe several efforts in our group to understand the power, reach and impact of AGN feedback processes. We find significant evidence for AGN feedback signatures even in low-luminosity AGN and we are now using molecular gas as a tracer to investigate if and how feedback may impact and quench galaxies at low redshift. At higher redshift, it appears that AGN-driven outflows can indeed suppress star formation in their hosts, consistent with the AGN having a `negative? impact on galaxy evolution. However, both star formation and quasar activity peak at z ~ 2-3 where AGN are expected to impact the build-up of stellar mass the most and I will present recent efforts in our group to characterise feedback processes in powerful AGN on CGM scales at and near Cosmic Noon. In particular, our team recently discovered a unique population of luminous high-z quasars (ERQs) with extreme outflow properties. At the same time, more and more exotic AGN populations with extreme signatures are being discovered at that redshift. These populations are ideal to obtain a census of the overall mass and energy budget of both outflow and infall/feeding from the CGM, an essential requirement to probe the detailed and full feedback loop. Finally, I will also introduce the JWST ERS Program "Q3D" which will study the impact of three carefully selected luminous quasars on their hosts. Our program will serve as a pathfinder for JWST science investigations in IFU mode.