Exascale simulations of discs around black holes

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• Yona Lapeyre (ENS de Lyon)
• Thursday 06 November 2025, 12:30-13:30
• Institute of Astronomy .

If you have a question about this talk, please contact Mika Kontiainen.

Lense-Thirring torque of a spinning black hole causes its accretion disc to warp. This so-called Bardeen-Petterson effect critically influences the direction and stability of the relativistic jets launched from supermassive black holes (SMBH), and could explain certain features in high frequency and type-C quasi periodic oscillations.

However, a lack of resolution in numerical simulations previously prevented the further characterization of such discs. While state-of-the-art simulations use 10 million SPH particles to reach an effective viscosity alpha of 0.01, a factor at least 10 in spatial resolution, meaning 1,000 in computational power, is required to allow local instabilities to grow. In particular the parametric instability, which is expected to be a primary physical source of wave damping and thus play a major role in the accretion mechanism, has yet to be captured in a warped disc simulation. Hence, the size of the misaligned region, the number and width of broken annuli if they exist, and the possibility of an observational signature of the disc bending are still to be determined.

During the last decade, GPUs have revolutionized the computing capability of supercomputers, breaking the exascale barrier (1018 FLOPS ) in 2022 with the Frontier cluster. SHAMROCK , a new astrophysics code published in March 2025, is one of the codes able to run on such machines. In this talk, I will present simulations of warped discs around SMBH at unprecedented resolutions, as well as the latest developments in the SHAMROCK code towards novel theoretical understanding of disc dynamics around black holes.

This talk is part of the IoA Dynamics Lunch series.

This talk is included in these lists:

• Institute of Astronomy
• IoA Dynamics Lunch

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