Fundamental physics with the Lyman-alpha forest: constraints on the growth of structure and neutrino masses from SDSS with effective field theory

TL;DR

This paper introduces an effective field theory approach to analyze Lyman-alpha forest data, providing competitive constraints on cosmological parameters and neutrino masses, and demonstrating the method's potential as an alternative to simulation-based techniques.

Contribution

It develops an EFT framework for Lyman-alpha forest analysis and applies it to SDSS data, achieving precise cosmological parameter measurements and neutrino mass constraints.

Findings

Measured σ8 with 2% precision, consistent with standard cosmology

Constrained total neutrino mass to less than 0.08 eV (95% CL)

Demonstrated the importance of informative priors for competitive constraints

Abstract

We present an effective field theory (EFT) approach to extract fundamental cosmological parameters from the Lyman-alpha forest flux fluctuations as an alternative to the standard simulation-based techniques. As a first application, we re-analyze the publicly available one-dimensional Lyman-alpha flux power spectrum data from the Sloan Digital Sky Survey. Our analysis relies on informative priors on EFT parameters which we extract from a combination of public hydrodynamic simulation and emulator data. Assuming the concordance cosmological model, our one-parameter analysis yields a $2\%$ measurement of the late time mass fluctuation amplitude $\sigma_8 = 0.841\pm 0.017$, or equivalently, the structure growth parameter $S_8 = 0.852\pm 0.017$, consistent with the standard cosmology. This result is obtained assuming that non-linear EFT parameters are cosmology-independent functions of the linear bias parameter. When this assumption is loosened, the limit degrades by a factor of 3, suggesting that informative priors are necessary for competitive constraints. Combining our EFT likelihood with Planck + baryon acoustic oscillation data, we find a new constraint on the total neutrino mass, $\sum m_\nu<$ 0.08 eV (at 95\% CL). Our study defines priorities for the development of EFT methods and sets the benchmark for cosmological analyses of the Lyman-alpha forest data from the Dark Energy Spectroscopic Instrument.