The gentle giant

The picture of our very own black hole is finally out. Glad to have played a small role in its interpretation in the BlackHoleCam and EventHorizonTelescope collaborations. See here for all the 10(!!) papers. But if you are in a hurry check out paper V which shows the large role of computational physics in today's discovery.

12th May 2022 by Oliver
tags: science

Science alert features paper on Boson stars

I'm happy to announce that our paper led by NOVA VIA Postdoc Hector Olivares was just featured on science alert.

In the study, we conducted GRMHD simulations of accretion onto condensations of light bosons called Boson stars. While Boson stars show little interaction with ordinary matter except for their gravitational pull, they do bend the light similar to a black hole. We find that, depending on the compactness (the ratio of mass to radius), some Boson stars also give rise to empty interiors, mimicking the shadow observed by the EHT. In our models however, the shadow turned out too small to account for the EHT observations of M87.

See the MNRAS paper for all the details!

Update: for a nice summary, see the following YouTube video by Anton Petrov.

9th Sep 2020; last edit 14th Oct 2020 by Oliver
tags: science

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Relativistic plasma dynamics


With numerical simulations of accreting compact objects, we study the transport of angular momentum and magnetic field, the ejection of relativistic jets and model horizon scale structure observed by the Event Horizon Telescope.

Pulsar Wind Nebulae

PWN are unique laboratories to investigate relativistic plasma. Among other things, they teach us about fluid instabilities, relativistic shocks, magnetic dissipation, particle acceleration and turbulent processes.

Radiative signatures

By modeling the non-thermal radiation emitted from astrophysical plasma, we extract important source parameters and understand particle energetization in a regime impossible to study in the laboratory.

Computational methods

The main tools of my research

Black Hole Accretion Code [BHAC]

Build upon the MPI-AMRVAC framework, the Black Hole Accretion Code solves the equations of general relativistic magnetohydrodynamics (GRMHD). Its modular design allows to simulate not only Einstein gravity, but also Black Holes in arbitrary metric theories of gravity and other compact objects. BHAC is the workhorse GRMHD-code for the blackholecam collaboration and provides source models for the Event Horizon Telescope Collaboration.

Adaptive Mesh Refinement Versatile Advection Code [MPI-AMRVAC]

With a current focus on solar- and non-relativistic astrophysical applications, MPI-AMRVAC offers a wide range of advanced features for the solution of (quasi-) conservation laws. Adaptive grids can be employed in cartesian, cylindrical and (stretched) spherical geometries. The code has been modernized recently and the documentation is frequently updated.