2026/07/29 by Stan Verhoeve, Dani de Boe, Gen Ye +1
Physics and Astronomy · #astro-ph.CO
35 pages, 9 figures
arxiv created 2026/07/29 · arxiv updated 2026/07/30
We present an extension of PyBird for one-loop large-scale structure analyses of modified gravity models. We implement support for quasi-static, Vainshtein-screened luminal Horndeski models (in EFTofDE and covariant formalisms) and nDGP, and replace the Green's function approach with a direct ODE method for computing the exact time-dependent functions entering the perturbation kernels. The new implementation improves computational efficiency while maintaining numerical consistency with the standard approach, and we validate the resulting one-loop matter power spectrum against N-body simulations for the αi∝Ω\rm DE parametrization. We apply this framework to constrain the αi ∝ a3 and αi ∝ Ω\rm DE parametrizations using Planck CMB, BOSS full-shape, and DESI DR2 BAO data, finding that full-shape information significantly tightens the constraints. We further showcase the pipeline for the cubic Galileon and nDGP models, demonstrating its applicability beyond the phenomenological amplitude parametrizations to covariant modified-gravity theories. Finally, we assess the impact of the Einstein--de Sitter approximation and find that exact time dependence can be retained at modest computational cost, which may become relevant for future large-scale structure surveys.