Black Hole Weather Forecasting with Deep Learning: A Pilot Study

TL;DR

This study demonstrates that deep learning models, specifically CNNs, can accurately and significantly faster predict the evolution of black hole accretion flows, offering a promising tool for astrophysical simulations.

Contribution

The paper introduces a CNN-based approach to forecast black hole accretion dynamics, achieving high accuracy and speed over traditional numerical methods.

Findings

CNNs predict accretion flow evolution over 80 dynamical times.

Deep neural networks evolve flows four orders of magnitude faster than traditional solvers.

The model generalizes well to unseen initial conditions.

Abstract

In this pilot study, we investigate the use of a deep learning (DL) model to temporally evolve the dynamics of gas accreting onto a black hole in the form of a radiatively inefficient accretion flow (RIAF). We have trained a machine to forecast such a spatiotemporally chaotic system -- i.e. black hole weather forecasting -- using a convolutional neural network (CNN) and a training dataset which consists of numerical solutions of the hydrodynamical equations, for a range of initial conditions. We find that deep neural networks seem to learn well black hole accretion physics and evolve the accretion flow orders of magnitude faster than traditional numerical solvers, while maintaining a reasonable accuracy for a long time. For instance, CNNs predict well the temporal evolution of a RIAF over a long duration of $8\times 10^4 GM/c^3$, which corresponds to 80 dynamical times at $r=100 GM/c^2$. The DL model is able to evolve flows from initial conditions not present in the training dataset with good accuracy. Our approach thus seems to generalize well. Once trained, the DL model evolves a turbulent RIAF on a single GPU four orders of magnitude faster than usual fluid dynamics integrators running in parallel on 200 CPU cores. We speculate that a data-driven machine learning approach should be very promising for accelerating not only fluid dynamics simulations, but also general relativistic magnetohydrodynamic ones.