July 7, 2025 to August 1, 2025
Ecole de Physique des Houches
Europe/Paris timezone

Accurate Small Scale Dynamics in COLA.

Jul 14, 2025, 4:50 PM
25m
Ecole de Physique des Houches

Ecole de Physique des Houches

École de physique des Houches 149 Chem. de la Côté, 74310 Les Houches

Speaker

Tristan Hoellinger (Institut d'Astrophysique de Paris)

Description

Ongoing galaxy surveys map the Universe’s large-scale structure with unprecedented fidelity across immense cosmological volumes. Cosmological inference at the field level demands thousands of N-body simulations. To fully exploit Stage-IV data, simulators must therefore produce fast, high-precision realisations spanning vast cosmological volumes and reaching deep into the non-linear regime. The COmoving Lagrangian Acceleration (COLA) algorithm accelerates large-scale cosmological simulations by decoupling the temporal evolution of large and small scales: large scales are evolved analytically using Lagrangian Perturbation Theory (LPT), while small scales are integrated numerically. Contrary to a common misconception, COLA does not inherently sacrifice small-scale accuracy for speed: the LPT change of frame of reference can be done with any force calculation technique. I show that accurate small-scale dynamics can be obtained at a tractable computational cost by employing Particle–Particle–Particle–Mesh (P3M) force evaluations within an LPT frame of reference, achieving the precision of tree-based codes down to scales of just a few particle lengths. This result is a significant advance towards fully harnessing the cosmological potential of Stage-IV galaxy surveys.

Primary author

Tristan Hoellinger (Institut d'Astrophysique de Paris)

Co-authors

Guilhem Lavaux (IAP) Florent Leclercq (Institut d'Astrophysique de Paris)

Presentation materials

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