##### FACULTY OF Physics and Astronomy

## PD DR. DOMINIK BOMANS, ASTRONOMICAL INSTITUTE

The research is focused on astrophysical plasma in interstellar and intergalactic space. Using multi-wavelength (UV, optical, IR, radio, and X-ray) space and ground based photometry and spectroscopy the physical state of the plasma is determined. This gives the ionization, heating, cooling, heavy element content, magnetization, and kin-ematics of the astrophysical plasma. With these measurements the stellar (radiative and mechanical) feedback on various spatial scales, from circumstellar to circumgalactic and intergalactic medium, can be determined. The analyses provide essential physical parameters for the understanding of dwarf and massive galaxy formation and evolution.

*Keywords: interstellar plasma, circum/intergalactic plasma, magnetized astrophysical plasma, stellar feedback, galaxy evolution*

Webpage: Astronomical Institute

##### Faculty of Physics and Astronomy

## PROF. DR. JULIA TJUS, PLASMA ASTROPARTICLE PHYSICS

The research of the chair “Theoretical Physics IV: Plasma-Astroparticle Physics” is focused on the theoretical de-scription of particle interactions and transport in astrophysica, magnetized plasmas. By solving the transport equation in the diffusive propagation regime, or the equation of motion in the ballistic regime, we aim to describe the multimessenger signatures from astrophysical objects like active or starburst galaxies, supernova remnants, and the Milky Way. A special focus lies in the interpretation of high-energy gamma-ray and neutrino signatures, with a participation in the instrumentation, operation, and data analysis of the Cherenkov Telescope Array (CTA), being built in La Palma and Chile, to measure TeV gamma-rays, as well as the IceCube Neutrino Observatory, lo-cated deep in the Antarctic Ice at the geographic South Pole. In our work, we use and develop numerical solvers of differential equations and apply machine learning methods to large data sets.

*Keywords: high-energy plasma-astrophysics, diffusive particle propagation, collisionless plasmas, machine learning, differential equations*

Webpage: Theoretical Physics IV

##### Faculty of Physics and Astronomy

## PROF. DR. HENDRIK HILDEBRANDT, OBSERVATIONAL COSMOLOGY, ASTRONOMICAL INSTITUTE

The research in our group is focussed on the exploitation of wide-field imaging surveys to study the effect of weak gravitational lensing of the large-scale structure of the Universe. This unique cosmological probe reveals the sta-tistical properties and evolution of the matter density field, which is described by the theory of cosmic structure formation. Precise measurements of this so-called cosmic shear effect constrain the values of important cosmologi-cal parameters like the total matter density and the amplitude of the power spectrum (i.e. the amount of clustering of matter). The gravitational lensing effect is inherently sensitive to all forms of matter and hence uniquely reveals (or makes visible) dark matter structures that dominate the matter budget of the Universe. Furthermore, their growth is influenced by the physical nature of the mysterious dark energy. In this way, our research is a direct window to study the dark Universe and extend our understanding at this very edge of our knowledge.

Keywords: Cosmology, Gravitational Lensing, Cosmic Shear, Wide-Field Imaging Surveys, Photometric Reds

Webpage: Astronomical Institute

##### FACULTY OF Physics and Astronomy

## PROF. DR. RAINER GRAUER, THEORETICAL PHYSICS I

The main interests of TP I are, on the one side, the development of multiphysics/multiscale simulations of colli-sionless plasmas and, on the other side, the understanding of intermittency in turbulent fluids and plasmas using non-perturbative methods. The first topic addresses the occurrence of multiple temporal and spatial scales in collisionless fusion, space, and astrophysical plasmas, which require different physical models at different scales. These models range from magnetohydrodynamics/Ohm's law (on large scales), two fluids/Maxwell to a kinetic description using the Vlasov/Maxwell system. The specialty of our group is the development of multiphysics/multiscale simulations that adaptively decide in which spatial region which model is appropriate, as well as coupled simulations of these different models. In the latter area, our group focuses on the non-perturbative in-stanton calculus to develop approximations to the path integral formulation of turbulence.

*Keywords: multiphysics/multiscale simulations, MHD, Vlasov, turbulence and instantons, intermittency*

Webpage: Theoretical Physics I

##### Faculty of Physics and Astronomy

## DR. JÜRGEN DREHER, CHAIR OF THEORETICAL PHYSICS I

Dr Jürgen Dreher is expert in theoretical plasma physics with emphasis on magnetized plasmas. He has studied various phenomena in the magnetosphere/ ionosphere system and the solar atmosphere, with special focus on magnetic reconnection. Combining theoretical modelling and numerical simulation, he has also been involved in the analysis of the Bochum "FlareLab" experiment. Dr. Dreher has created the mesh-adaptive, massively-parallel simulation framework "racoon," which was employed in numerous plasma physical projects. Recently, he has been working on adopting those techniques and numerical methods to the field of cardiac electrophysiology.

*Keywords: Plasma and fluid theory, Space plasma physics, Numerical methods and code development, Large-scale numerical simulation*

Webpage: Theoretical Physics I

##### FACULTY OF Physics and Astronomy

## PROF. DR. ANDREAS WIECK, CHAIR FOR APPLIED SOLID STATE PHYSICS

Andreas Wieck is the director of the Institute of Experimental Physics and professor in the Department for Physics and Astronomy at RUB, holding since 1993 the Chair of Applied Solid State Physics. He performs Molecular Beam Epitaxy in ultra-high vacuum of IIIV-compounds as AlxGa1-xAs and InyGa1-yAs with thicknesses of sub-atomic layers up to 10µm, using band-gap engineering and dopants as Si and C to create on 3”-wafers High-Electron-Mobility-Transistors, Quantum Wells and Quantum Dots to produce light emitting diodes, laser diodes, transistors and single photon sources for quantum informatics and cryptography. He pioneered Focused Ion Beams for mask-less doping and sputtering. Andreas obtained his PhD with experiments at the High-Field Magnet Laboratory in Grenoble/France at the University of Hamburg, was 8 years tenure researcher at the Max-Planck-Institute for Sol-id-State-Research/Stuttgart and 1 year at the NTT Basic Research Labs in Tokyo/Japan before joining RUB.

*Keywords: Molecular Beam Epitaxy, Quantum Dots, Focused Ion Beams*

Webpage: Theoretical Physics VI

##### Faculty of Physics and Astronomy

## PD DR. HORST FICHTNER, CHAIR OF THEORETICAL PHYSICS IV

The research is mainly focused on the acceleration and propagation of non-thermal particle populations and on fluctuations in high-temperature plasmas. Regarding the first topic the activities comprise the theory of newly introduced regularized kappa distributions for the treatment of suprathermal particles, an analysis of nonlinear diffusive shock acceleration of intermediate-energy cosmic rays, and the propagation of high-energy cosmic ray particles in the direct vicinity of the Sun. With respect to the second topic, the transport of fluctuations in the sub-sonic plasma in the so-called inner helisosheath of the heliosphere is studied as well as the wave-driving of the solar wind within the solar corona. The corresponding frameworks reach from the equations of motions of indi-vidual particles, via kinetic transport equations for distributions functions, to the magnetohydrodynamic fluid modelling of their velocity moments.

*Keywords: space and astrophysical plasmas, kinetic theory, magnetohydrodynamics, plasma fluctuations *

Webpage: Theoretical Physics IV