From observations to simulations: A neural-network approach to intracluster medium kinematics

¹ Max-Planck-Institut für Extraterrestrische Physik, Gießenbachstraße 1, 85748, Garching, Germany
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138, USA
³ Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
⁴ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing, 102206, China
⁵ INAF – IASF Palermo, Via U. La Malfa 153, I-90146, Palermo, Italy
⁶ Department of Physics and Astronomy, University of Alabama in Huntsville, Huntsville, AL, 35899, USA

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 24 November 2025
Accepted: 25 April 2026

Abstract

We present a systematic comparison between XMM-Newton velocity maps of the Virgo, Centaurus, Ophiuchus, and A3266 clusters and synthetic velocity maps generated from the Illustris TNG-300 simulated clusters. Our goal is to constrain the physical conditions and dynamical states of the intracluster medium (ICM) through a data-driven approach. We employed a Siamese convolutional neural network (CNN) designed to identify the most analogous simulated cluster to each observed system based on the morphology of their line-of-sight velocity maps. The model learns a high-dimensional similarity metric between observations and simulated clusters, allowing us to capture subtle kinematic and structural patterns beyond traditional statistical tests. We find that the best-matching simulated halos reproduce the observed large-scale velocity gradients and local kinematic substructures, suggesting that the ICM motions in these clusters arise from a combination of gas sloshing, active galactic nucleus feedback, and minor merger activity. Our results demonstrate that deep learning provides a powerful and objective framework for connecting X-ray observations to cosmological simulations, offering new insights into the dynamical evolution of galaxy clusters and the mechanisms driving turbulence and bulk flows in the hot ICM.