BibTeX

@article{2505.13591v1,
Author        = {Gemma Zhang and Chirag Modi and Oliver H. E. Philcox},
Title         = {Modeling Galaxy Surveys with Hybrid SBI},
Eprint        = {2505.13591v1},
ArchivePrefix = {arXiv},
PrimaryClass  = {astro-ph.CO},
Abstract      = {Simulation-based inference (SBI) has emerged as a powerful tool for
extracting cosmological information from galaxy surveys deep into the
non-linear regime. Despite its great promise, its application is limited by the
computational cost of running simulations that can describe the
increasingly-large cosmological datasets. Recent work proposed a hybrid SBI
framework (HySBI), which combines SBI on small-scales with perturbation theory
(PT) on large-scales, allowing information to be extracted from high-resolution
observations without large-volume simulations. In this work, we lay out the
HySBI framework for galaxy clustering, a key step towards its application to
next-generation datasets. We study the choice of priors on the parameters for
modeling galaxies in PT analysis and in simulation-based analyses, as well as
investigate their cosmology dependence. By jointly modeling large- and
small-scale statistics and their associated nuisance parameters, we show that
HySBI can obtain 20\% and 60\% tighter constraints on $\Omega_m$ and
$\sigma_8$, respectively, compared to traditional PT analyses, thus
demonstrating the efficacy of this approach to maximally extract information
from upcoming spectroscopic datasets.},
Year          = {2025},
Month         = {May},
Url           = {http://arxiv.org/abs/2505.13591v1},
File          = {2505.13591v1.pdf}
}