Generation of Lognormal Synthetic Lyman-$\alpha$ Forest Spectra for $P_{1D}$ Analysis

Abstract

The one-dimensional flux power spectrum (P1D) of the Lyman-$\alpha$ forest probes small-scale structure in the intergalactic medium (IGM) and is therefore sensitive to a variety of cosmological and astrophysical parameters. These include the amplitude and shape of the matter power spectrum, the thermal history of the IGM, the sum of neutrino masses, and potential small-scale fluctuations due to the nature of dark matter. However, P1D is also highly sensitive to observational and instrumental systematics, making accurate synthetic spectra essential for validating analyses and quantifying these effects, especially in high-volume surveys like the Dark Energy Spectroscopic Instrument (DESI). We present an efficient lognormal mock framework for generating one-dimensional Lyman-$\alpha$ forest spectra tailored for P1D analysis. Our method captures the redshift evolution of the mean transmitted flux and the scale-dependent shape and amplitude of the one-dimensional flux power spectrum by tuning Gaussian field correlations and transformation parameters. Across the DESI Early Data Release (EDR) redshift range ($2.0\le z\le 3.8$), and a wide range of scales ($10^{-4}$ s km${}^{-1}\le k\le 1.0$ s km${}^{-1}$), our mocks recover the mean flux evolution with redshift to sub-percent accuracy, and the P1D at the percent level. Additionally, we discuss potential extensions of this framework, such as the incorporation of astrophysical contaminants, continuum uncertainties, and instrumental effects. Such improvements would expand its utility in ongoing and upcoming surveys and enable a broader range of validation efforts and systematics studies for P1D inference and precision cosmology.

arXiv comment21 pages, 5 figures, 1 table, submitted to JCAP

References in corpus (47)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Baryon Oscillation Spectroscopic Survey of SDSS-III
• Observational Probes of Cosmic Acceleration
• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• Cosmological parameter analysis including SDSS Ly-alpha forest and galaxy bias: constraints on the primordial spectrum of fluctuations, neutrino mass, and dark energy
• The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Overview and Early Data
• Warm Dark Matter as a solution to the small scale crisis: new constraints from high redshift Lyman-alpha forest data
• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
• The Lyman-alpha Forest Power Spectrum from the Sloan Digital Sky Survey
• Recovery of the Power Spectrum of Mass Fluctuations from Observations of the Lyman-alpha Forest
• The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Baryon acoustic oscillations with Lyman-$\alpha$ forests
• The Evolution of the Intergalactic Medium
• Neutrino masses and cosmology with Lyman-alpha forest power spectrum
• Nyx: A Massively Parallel AMR Code for Computational Cosmology
• Measurement of Baryon Acoustic Oscillations in the Lyman-alpha Forest Fluctuations in BOSS Data Release 9
• DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• The one-dimensional Ly-alpha forest power spectrum from BOSS
• Lyman-alpha Forests cool Warm Dark Matter
• A Refined Measurement of the Mean Transmitted Flux in the Ly-alpha Forest over 2 < z < 5 Using Composite Quasar Spectra
• Cosmological and astrophysical parameters from the SDSS flux power spectrum and hydrodynamical simulations of the Lyman-alpha forest
• Improving lognormal models for cosmological fields
• The one-dimensional power spectrum from the SDSS DR14 Ly$\alpha$ forests
• Revealing reionization with the thermal history of the intergalactic medium: new constraints from the Lyman-$\alpha$ flux power spectrum
• Constraint on neutrino masses from SDSS-III/BOSS Ly$\alpha$ forest and other cosmological probes
• DESI DR2 Results I: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• New Constraints on Warm Dark Matter from the Lyman-$\alpha$ Forest Power Spectrum
• The Lyman-alpha forest power spectrum from the XQ-100 Legacy Survey
• Constraints on the Primordial Power Spectrum from High Resolution Lyman-alpha Forest Spectra and WMAP
• On the effect of the ionising background on the Lyα forest autocorrelation function
• A New Precision Measurement of the Small-Scale Line-of-Sight Power Spectrum of the Ly$\alpha$ Forest
• An Emulator for the Lyman-alpha Forest
• LyaCoLoRe: Synthetic Datasets for Current and Future Lyman-$\alpha$ Forest BAO Surveys
• The Dark Energy Spectroscopic Instrument: One-dimensional power spectrum from first Lyman-$\alpha$ forest samples with Fast Fourier Transform
• Generating mock data sets for large-scale Lyman-α forest correlation measurements
• Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum
• Inferring the Thermal History of the Intergalactic Medium from the Properties of the Hydrogen and Helium Lyman-alpha Forest
• Mock Quasar-Lyman-α Forest Data-sets for the SDSS-III Baryon Oscillation Spectroscopic Survey
• Optimal 1D Ly-$\alpha$ Forest Power Spectrum Estimation I: DESI-Lite Spectra
• GLASS: Generator for Large Scale Structure
• Effects of Photoionization and Photoheating on Lyman-alpha Forest Properties from Cholla Cosmological Simulations
• A neural network emulator for the Lyman-$\alpha$ 1D flux power spectrum
• Synthetic spectra for Lyman-$\alpha$ forest analysis in the Dark Energy Spectroscopic Instrument