DISCO-DJ II: a differentiable particle-mesh code for cosmology
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866909828596629504 |
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| author | List, Florian Hahn, Oliver Flöss, Thomas Winkler, Lukas |
| author_facet | List, Florian Hahn, Oliver Flöss, Thomas Winkler, Lukas |
| contents | The mildly non-linear regime of cosmic structure formation holds much of the information that upcoming large-scale structure surveys aim to exploit, making fast and accurate predictions on these scales essential. We present the $N$-body module of DISCO-DJ (DIfferentiable Simulations for COsmology - Done with Jax), designed to deliver high-fidelity, GPU-accelerated, and differentiable particle-mesh simulations tailored for cosmological inference. Theory-informed time integrators such as the recently introduced BullFrog method allow for accurate predictions already with few time steps (e.g. $6$ steps for per-cent-level accuracy in terms of the present-day power spectrum at $k \approx 0.2 \, h / \mathrm{Mpc}$ using $N = 512^3$ particles, which takes just a few seconds). To control discreteness effects and achieve high accuracy, the code incorporates a suite of advanced techniques, for example a custom non-uniform FFT implementation for force evaluation. Both forward- and reverse-mode differentiation are supported, with memory requirements independent of the number of time steps; in the reverse case, this is achieved through an adjoint formulation. We extensively study the effect of various numerical parameters on the accuracy. As an application of DISCO-DJ, we perform field-level inference by recovering $σ_8$ and the initial conditions from a noisy Gadget matter density field. Coupled with our recently introduced Einstein--Boltzmann solver, the DISCO-DJ ecosystem provides a self-consistent, fully differentiable pipeline for modelling the large-scale structure of the universe. The code is available at https://github.com/cosmo-sims/DISCO-DJ. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_05206 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | DISCO-DJ II: a differentiable particle-mesh code for cosmology List, Florian Hahn, Oliver Flöss, Thomas Winkler, Lukas Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics The mildly non-linear regime of cosmic structure formation holds much of the information that upcoming large-scale structure surveys aim to exploit, making fast and accurate predictions on these scales essential. We present the $N$-body module of DISCO-DJ (DIfferentiable Simulations for COsmology - Done with Jax), designed to deliver high-fidelity, GPU-accelerated, and differentiable particle-mesh simulations tailored for cosmological inference. Theory-informed time integrators such as the recently introduced BullFrog method allow for accurate predictions already with few time steps (e.g. $6$ steps for per-cent-level accuracy in terms of the present-day power spectrum at $k \approx 0.2 \, h / \mathrm{Mpc}$ using $N = 512^3$ particles, which takes just a few seconds). To control discreteness effects and achieve high accuracy, the code incorporates a suite of advanced techniques, for example a custom non-uniform FFT implementation for force evaluation. Both forward- and reverse-mode differentiation are supported, with memory requirements independent of the number of time steps; in the reverse case, this is achieved through an adjoint formulation. We extensively study the effect of various numerical parameters on the accuracy. As an application of DISCO-DJ, we perform field-level inference by recovering $σ_8$ and the initial conditions from a noisy Gadget matter density field. Coupled with our recently introduced Einstein--Boltzmann solver, the DISCO-DJ ecosystem provides a self-consistent, fully differentiable pipeline for modelling the large-scale structure of the universe. The code is available at https://github.com/cosmo-sims/DISCO-DJ. |
| title | DISCO-DJ II: a differentiable particle-mesh code for cosmology |
| topic | Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2510.05206 |