Numerical simulations are the most important tools in my research. For the different physical Applications have emerged from various software packages in my work group over the years. Essentially, these are codes that illuminate various aspects of astroplasmaphysics: from MHD fluids to the modeling of hadronic AGN blobs.

Particle-in-Cell

Particle-in-Cell (PiC) codes are a very popular method to simulate kinetic plasmas. The distribution function is represented by pseudoparticles that interact with electromagnetic fields on a grid.

My working group has developed two PiC codes: ACRONYM for production runs ( The Influence of the Mass Ratio on Particle Acceleration by the Filamentation Instability (Kilian, Burkart, and Spanier 2012, High Performance Computing in Science and Engineering '11) ). ACRONYM is used for simulations in astrophysics, space physics and also for laboratory plasmas in particle physics. ACRONYM is now being further developed by a consortium from several countries.

More on ACRONYM

In addition, another parallelized PiC code was developed completely in C ++ 11: PICPANTHER: A simple, concise implementation of the relativistic moment implicit particle-in-cell method (Kempf, Kilian, Ganse, Schreiner, and Spanier 2015, Computer Physics Communications) . PiCPANTHER is freely available and contains the basic elements of ACRONYM. Through the consistent use of modern C ++ 11 is PiCPANTHER an easily understandable and portable code

AGN modeling

The modeling of Active Galactic Nuclei is mostly based on a solution of the Vlasov equation together with radiation processes and a radiation transport equation. Due to the high complexity and size of AGN jets, most AGN models assume a homogeneous-isotropic emission region in which the Vlasov equation has only one impulse dimension.

The most important distinctions of models are mostly between leptonic and lepto-hadronic models, as well as the distinction between static and dynamic models.

Several simulation codes have been developed in my work group over the years. Currently in use are

• UNICORN: A spatially resolved, time-dependent, leptohadronic code, where Fermi acceleration within the jet is calculated based on fluid shock profiles. A Numerical Model of Parsec-scale SSC Morphologies and Their Radio Emission (Richter and Spanier 2016, The Astrophysical Journal) )
• UNICORN-0D: A variant of UNICORN that contains all technical features, but uses a homogeneous-isotropic geometry (i.e. no spatial resolution) and calculates particle acceleration on the basis of a two-zone model. ( AGN neutrino flux estimates for a realistic hybrid model (Richter and Spanier 2018, Astroparticle Physics) < / A>)

A more detailed description can be found here: UNICORN