The Dark Energy Spectroscopic Instrument: one-dimensional power spectrum from first Ly α forest samples with Fast Fourier Transform
C. Ravoux, Marie Lynn Abdul Karim, E. Armengaud, Michael Walther, Naim Göksel Karaçaylı, Paul Martini, Julien Guy, J. Aguilar, S. P. Ahlen, S. Bailey, Julian Bautista, S. F. Beltran, David J. Brooks, L. Cabayol-Garcia, Solène Chabanier, E. Chaussidon, J. Chaves-Montero, Kyle Dawson, Rodrigo de la Cruz, Axel de la Macorra, P. Doel, K. Fanning, Andreu Font-Ribera, J. E. Forero-Romero, Satya Gontcho A Gontcho, Alma X. González‐Morales, Calum Gordon, H. K. Herrera-Alcantar, K. Honscheid, Vid Iršič, Mustapha Ishak, R. Kehoe, Theodore Kisner, Anthony Kremin, Martin Landriau, L. Le Guillou, M. E. Levi, Zarija Lukić, C. Magneville, Aaron Meisner, R. Miquel, John Moustakas, Eva-Maria Mueller, A. Muñoz-Gutiérrez, L. Napolitano, Jundan Nie, Gustavo Niz, N. Palanque‐Delabrouille, Will J. Percival, Ignasi Pérez-Ràfols, Matthew M. Pieri, Claire Poppett, Francisco Prada, César Ramírez Pérez, Graziano Rossi, E. Sánchez, David J. Schlegel, M. Schubnell, Hee‐Jong Seo, Francesco Sinigaglia, T. Tan, G. Tarlé, Ben Wang, Benjamin A. Weaver, Christophe Yèche, Zhimin Zhou
Abstract
ABSTRACT We present the one-dimensional Ly α 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 2 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 with the new DESI instrument, applying techniques similar to previous Sloan Digital Sky Survey (SDSS) measurements. We use synthetic data based on lognormal 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 Ly α forest sample than SDSS, providing an unprecedented precise one-dimensional power spectrum measurement.