The Dark Energy Spectroscopic Instrument: One-dimensional power spectrum from first Lyman-$\alpha$ forest samples with Fast Fourier Transform

Abstract

We present the one-dimensional Lyman-$\alpha$ forest power spectrum measurement using the first data provided by the Dark Energy Spectroscopic Instrument (DESI). The data sample comprises $26,330$ quasar spectra, at redshift $z>2.1$, contained in the DESI Early Data Release and the first two months of the main survey. We employ a Fast Fourier Transform (FFT) estimator and compare the resulting power spectrum to an alternative likelihood-based method in a companion paper. We investigate methodological and instrumental contaminants associated to the new DESI instrument, applying techniques similar to previous Sloan Digital Sky Survey (SDSS) measurements. We use synthetic data based on log-normal approximation to validate and correct our measurement. We compare our resulting power spectrum with previous SDSS and high-resolution measurements. With relatively small number statistics, we successfully perform the FFT measurement, which is already competitive in terms of the scale range. At the end of the DESI survey, we expect a five times larger Lyman-$\alpha$ forest sample than SDSS, providing an unprecedented precise one-dimensional power spectrum measurement.

23 pages, 23 figures, Journal version

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Cited by in corpus (21)

• The Early Data Release of the Dark Energy Spectroscopic Instrument
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• Cosmological Constraints from the eBOSS Lyman-$\alpha$ Forest using the PRIYA Simulations
• The 3D Lyman-$\alpha$ Forest Power Spectrum from eBOSS DR16
• Synthetic spectra for Lyman-$\alpha$ forest analysis in the Dark Energy Spectroscopic Instrument
• The ACCEL2 Project: Precision Measurements of EFT Parameters and BAO Peak Shifts for the Lyman-$\alpha$ Forest
• Measurement of the small-scale 3D Lyman-$\alpha$ forest power spectrum
• Ly$\alpha$NNA: A Deep Learning Field-level Inference Machine for the Lyman-$\alpha$ Forest
• The long-lasting effect of X-ray preheating in the post-reionization intergalactic medium
• The Compressed 3D Lyman-Alpha Forest Bispectrum
• Reionization relics in the cross-correlation between the Ly$\alpha$ forest and 21 cm intensity mapping in the post-reionization era
• Simulating the epoch of Helium Reionization in photon-conserving semi-numerical code SCRIPT
• ForestFlow: predicting the Lyman-$\alpha$ forest clustering from linear to nonlinear scales
• An improved model for the effect of correlated Si-III absorption on the one-dimensional Lyman-$\alpha$ forest power spectrum
• Modeling the Cosmological Lyman-$\alpha$ Forest at the Field Level
• Bridging Simulations and EFT: A Hybrid Model of the Lyman-Alpha Forest Field
• DESI DR1 Lyα 1D power spectrum: The Fast Fourier Transform estimator measurement
• Unified reconstruction of the Lyman-alpha power spectrum with Hamiltonian Monte Carlo
• Lya2pcf: an efficient pipeline to estimate two- and three-point correlation functions of the Lyman-$\alpha$ forest
• Generation of Lognormal Synthetic Lyman-$\alpha$ Forest Spectra for $P_{1D}$ Analysis