Japan-Germany Joint Seminar on cosmology and astroparticle physics
In this seminar series, we organize various seminars about cosmology and astroparticle physics.
The focused topics are
Axion and axion like particle
Dark matter
Structure formation
QCD physics in cosmology
Non-linear dynamics and thermalization
Gravitational wave astronomy
Gravitational lensing
Magnetic field in the Universe
Polarization analyses in cosmological and astrophysical observations
Radio astronomy
All the seminars will be in the online format. If you want to receive the information of this seminar series, please register from here.
Forthcoming seminars
Joint Seminar (Informal)
Speaker: Atsushi Nishizawa (The University of Tokyo, RESCEU)
Time and Date: 5:00pm in JST / 9:00am in CET, January 26th, 2023
Title: On the detection of circularly-polarized gravitational-wave backgrounds with pulsar timing
Joint Seminar 7
Speaker: Axel Brandenburg (Nordita)
Time and Date: 5:00pm in JST / 9:00am in CET, January 30th, 2023
Title: Origins of cosmic magnetism
Abstract: The magnetic fields of cosmic bodies like the Earth or the Sun have puzzled scientists for well over a hundred years. The basic principle is that of a self-excited dynamo, which is an electric generator where the weak permanent magnets are replaced by electromagnets. But cosmic dynamos are made of plasma with no wires and uniform conductivity, so they are prone to short-circuiting themselves. We now know of a handful of very different examples where a suitable flow geometry can exponentially amplify weak seed fields. Demonstrating this experimentally is still hard, but it did work in a few case. It is much easier on the computer. After explaining some of the examples, I will address the problem of primordial magnetic fields. For a long time, this was thought to be an alternative to galactic dynamos, but now we know that it is very much a research field in its own right. Not much is known with certainty, but there are believed to be lower observational limits on their strength. The field generation would also leave traces in relic gravitational waves, which is a rapidly growing topic that I will address at the end.
Organizers: Yuko Urakawa (Chair), Aritra Basu, Kiyotomo Ichiki, Naoya Kitajima, Atsushi Nishizawa, Masamune Oguri, Dominik Schwarz, Joris Verbiest
If you have any question, please contact us from here.