The Supercomputer MACH-2: Use Cases
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Use Case: Stellar-Wind Interaction and Particle Acceleration in Gamma-Ray Binaries
Involved Scientists
- D. Huber, R. Kissmann, O. Reimer (Institut für Astro- und Teilchenphysik,
Leopold-Franzens-Universität Innsbruck)
Description of the Application
Gamma-ray binaries are binary systems consisting of an early-type star and a
compact object, which predominantly emit radiation in the gamma-ray band. A
popular model to explain this gamma-ray emission is the so-called
pulsar-wind scenario. In this case, the compact object is assumed to be a
pulsar emitting a relativistic pulsar wind. This wind collides with the
stellar wind from the early-type star, producing a wind-collision region
bounded by strong shock waves. These shock waves are sites, where particles
can be accelerated to very high energies. Then, the non-thermal emission of
the system is explained as synchrotron and inverse-Compton emission of these
high-energy particles.
Figure: The turbulent interaction of the stellar winds of a pulsar and a
giant star leads to the formation of an extended collision zone, in which
particles can be accelerated to highest energies. (credit: D. Huber)
We modelled these systems using relativistic hydrodynamics for the stellar
and pulsar wind, additionally solving a particle-transport equation for the
high-energy particles [1,2]. Corresponding simulations need high-resolution
in space and energy. Additionally, due to the relativistic speed of the
pulsar wind, timesteps need to be very small. In total simulating such a
system requires large computational resources, where we used MPI to
distribute the workload over multiply computing cores. Given the hyperbolic
nature of the equations of relativistic hydrodynamics such a distribution in
space is easily possible, where we used a relativistic extension of the
CRONOS code [3,4].
References
- Huber, D., Kissmann, R., Reimer, A., and Reimer, O. Relativistic fluid modelling of gamma-ray binaries. I. The model. A&A, 646,
A91 (2021). doi: 10.1051/0004-6361/202039277.
- Huber, D., Kissmann, R., and Reimer, O. Relativistic fluid modelling of gamma-ray binaries.
II. Application to LS 5039. A&A, 649, A71 (2021). doi:
10.1051/0004-6361/202039278.
- Kissmann, R., Kleimann, J., Krebl, B., and Wiengarten, T. The CRONOS Code for
Astrophysical Magnetohydrodynamics. ApJS, 236, 53 (2018). doi:
10.3847/1538-4365/aabe75.
- Huber, D. and Kissmann, R. Special relativistic hydrodynamics with CRONOS. A&A, 653,
A164 (2021). doi: 10.1051/0004-6361/202141364.
JKU Scientific Computing Administration