Mapping the Three-dimensional Lyα Forest Large-scale Structure in Real and Redshift Space

Sinigaglia, Francesco; Kitaura, Francisco-Shu; Balaguera-Antolínez, Andrés; Shimizu, Ikkoh; Nagamine, Kentaro; Sánchez-Benavente, Manuel; Ata, Metin
Bibliographical reference

The Astrophysical Journal

Advertised on:
Number of authors
IAC number of authors
Refereed citations
This work presents a new physically motivated supervised machine-learning method, HYDRO-BAM, to reproduce the three-dimensional Lyα forest field in real and redshift space, which learns from a reference hydrodynamic simulation and thereby saves about seven orders of magnitude in computing time. We show that our method is accurate up to k ~ 1 h Mpc-1 in the one- (probability distribution function), two- (power spectra), and three-point (bispectra) statistics of the reconstructed fields. When compared to the reference simulation including redshift-space distortions, our method achieves deviations of ≲2% up to k = 0.6 h Mpc-1 in the monopole and ≲5% up to k = 0.9 h Mpc-1 in the quadrupole. The bispectrum is well reproduced for triangle configurations with sides up to k = 0.8 h Mpc-1. In contrast, the commonly adopted Fluctuating Gunn-Peterson approximation shows significant deviations, already when peculiar motions are not included (real space) at configurations with sides of k = 0.2-0.4 h Mpc-1 in the bispectrum and is also significantly less accurate in the power spectrum (within 5% up to k = 0.7 h Mpc-1). We conclude that an accurate analysis of the Lyα forest requires considering the complex baryonic thermodynamical large-scale structure relations. Our hierarchical domain-specific machine-learning method can efficiently exploit this and is ready to generate accurate Lyα forest mock catalogs covering the large volumes required by surveys such as DESI and WEAVE. * Released on 2022 January 20.
Related projects
 The Invisible Scaffolding of Space
Cosmology with Large Scale Structure Probes

The Cosmic Microwave Background (CMB) contains the statistical information about the early seeds of the structure formation in our Universe. Its natural counterpart in the local universe is the distribution of galaxies that arises as a result of gravitational growth of those primordial and small density fluctuations. The characterization of the