arXiv Machine Learning

Graph Neural Networks for Astrophysics and Cosmology

Graph Neural Networks (GNNs) are presented as a natural framework for modeling the relational structure inherent in astrophysical and cosmological data, such as galaxies in their environments or photons in detectors. The review argues that GNNs align with the native geometry of these domains, incorporate existing symmetries and prior knowledge, and remain flexible enough to capture unknown phenomena, offering greater interpretability than other deep‑learning models. It surveys applications across cosmology, galaxy formation, dynamics, and instrumentation, noting that only about one in six non‑instrumentation papers apply GNNs to real data rather than simulations, and provides best‑practice guidelines for when to use or avoid graph approaches.

arXiv Machine Learning
Aug 6

Galaxy Phase-Space and Field-Level Cosmology: The Strength of Semi-Analytic Models

arXiv:2512. 10222v2 Announce Type: replace-cross Abstract: Semi-analytic models are a widely used approach to simulate galaxy properties within a cosmological framework, relying on simplified yet physically motivated prescriptions.

By Natal\'i S. M. de Santi, Francisco Villaescusa-Navarro, Pablo Araya-Araya, Gabriella De Lucia, Fabio Fontanot, Lucia A. Perez, Manuel Arn\'es-Curto, Violeta Gonzalez-Perez, \'Angel Chandro-G\'omez, Rachel S. Somerville, Tiago Castro
arXiv Machine Learning
Oct 19

Learning without relearning physical symmetry: an SO(3)-equivariant convolutional network (CNN) on the sphere

The paper introduces a novel SO(3)-equivariant convolutional neural network designed for data on the sphere, specifically using the Hierarchical Equal Area isoLatitude Pixelization (HEALPix). By employing steerable filters, parallel transport, and spin-weighted features, the architecture guarantees exact equivariance and avoids the need for the network to learn spherical symmetry from data. Benchmarks show the model achieves percent-level SO(3)-invariance error and outperforms existing methods in dense gradient regression, cosmic microwave background foreground removal, and denoising tasks.

By Joshua Williamson, Niall Jeffrey, Lorne Whiteway
arXiv Machine Learning
Oct 2

Reconstruction of cosmic-ray direction and energy in radio arrays using deep ensemble graph neural networks

The paper presents a deep ensemble graph neural network (GNN) approach for reconstructing the arrival direction and energy of ultra‑high‑energy cosmic rays from voltage traces recorded by ground‑based radio detector arrays. Triggered antennas are modeled as a graph input to the GNN, and physical knowledge is embedded in both the architecture and data to improve precision while reducing training set size. The method achieves an angular resolution of 0.092° and an electromagnetic energy resolution of 16.4% on simulated data with realistic noise, and includes uncertainty estimation and robustness checks for real‑world applicability.

By Ars\`ene Ferri\`ere, Aur\'elien Benoit-L\'evy, Olivier Martineau-Huynh, Mat\'ias Tueros
arXiv AI
Oct 28

ASTROLABE: A 3D Particle-Level Surrogate for Cosmology Simulation with Physical Flow Matching

ASTROLABE is a flow‑matching generative emulator that operates directly on the 6N phase‑space coordinates of individual particles, avoiding voxel grids and allowing any observable to be measured from inference. It uses a field‑particle hybrid transformer so that compute and memory scale linearly with the number of particles, and incorporates physical flow matching by basing the prior on COLA‑derived coordinates with momentum and mass conservation enforced throughout the flow. In Lambda‑CDM tests, ASTROLABE reproduces realistic fields, accurate power spectra, halo mass functions, velocity profiles, and halo density profiles, and it generalizes to out‑of‑distribution dark‑acoustic oscillation initial conditions while also being fine‑tuned to emulate large‑scale simulations such as TNG50‑3‑dark at a fraction of the cost.

By Ibrahim Elsharkawy, David Curtin, Yonatan Kahn, Neal Weiner
arXiv Machine Learning
Oct 12

Learning Schwarzschild Geodesic Motion with Lagrangian Neural Networks

The paper presents a method for training Lagrangian Neural Networks (LNNs) to learn Schwarzschild geodesic motion. By introducing a decoupled position–velocity normalization and an energy-constrained log-uniform sampling strategy, the authors achieve accurate reproduction of perihelion precession, relativistic time dilation, and conservation of energy and angular momentum across diverse orbital regimes. This work marks the first successful training of LNNs on Schwarzschild geodesics and demonstrates their potential for data-driven modeling of complex relativistic systems.

By Sukru Caglar, Sena Kalabalik, Abdullah Umut Hamzaogullari, Arkadas Ozakin