Studying baryon acoustic oscillations using photometric redshifts from the DESI Legacy Imaging survey DR9

¹ Max Planck Institute for Extraterrestrial Physics, Gießenbachstraße 1, 85748 Garching, Germany
² Universitäts-Sternwarte München, Scheinerstraße 1, 81679 Munich, Germany
³ Korea Astronomy & Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, 34055 Daejeon, Republic of Korea
⁴ Chosun University, Chosundaegil 146, Dong-gu, 61452 Gwangju, Republic of Korea
⁵ School of Physics and Astronomy, Sun Yat-sen University, 2 Daxue Road, Tangjia, Zhuhai 519082, China
⁶ CSST Science Center for the Guangdong-Hong kong-Macau Greater Bay Area, SYSU, Zhuhai, China
⁷ Center for Cosmology and AstroParticle Physics, The Ohio State University, Columbus, OH 43210, USA
⁸ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
⁹ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, 3941 O’Hara St., Pittsburgh, PA 15260, USA
¹⁰ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA
¹¹ Physics Dept., Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
¹² NSF NOIRLab, 950 N. Cherry Ave., Tucson, AZ 85719, USA
¹³ Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
¹⁴ Instituto de Física, Universidad Nacional Autónoma de México, Cd. de México C.P. 04510, Mexico
¹⁵ Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
¹⁶ Departamento de Física, Universidad de los Andes, Cra. 1 No. 18A-10, Edificio Ip, CP 111711 Bogotá, Colombia
¹⁷ Observatorio Astronómico, Universidad de los Andes, Cra. 1 No. 18A-10, Edificio H, CP 111711 Bogotá, Colombia
¹⁸ Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
¹⁹ Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX, UK
²⁰ Institute of Space Sciences, ICE-CSIC, Campus UAB, Carrer de Can Magrans s/n, 08913 Bellaterra, Barcelona, Spain
²¹ Fermi National Accelerator Laboratory, PO Box 500 Batavia, IL 60510, USA
²² Department of Physics and Astronomy, University of California Irvine 92697, USA
²³ Sorbonne Université, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), FR-75005 Paris, France
²⁴ Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK
²⁵ Instituto de Física, Universidad Nacional Autónoma de México, Cd. de México C.P. 04510, Mexico
²⁶ Departamento de Física, Universidad de Guanajuato - DCI, C.P. 37150 Leon, Guanajuato, Mexico
²⁷ Instituto Avanzado de Cosmología A. C., San Marcos 11 - Atenas 202. Magdalena Contreras, 10720 Ciudad de México, Mexico
²⁸ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, s/n, E-18008 Granada, Spain
²⁹ Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, KS 66506, USA
³⁰ Department of Physics and Astronomy, Sejong University, Seoul 143-747, Korea
³¹ CIEMAT, Avenida Complutense 40, E-28040 Madrid, Spain
³² University of Michigan, Ann Arbor, MI 48109, USA
³³ National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Rd., Chaoyang District, Beijing 100012, PR China

^⋆ Corresponding author; ysong@kasi.re.kr

Received: 27 August 2024
Accepted: 17 January 2025

Abstract

Context. The Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Survey DR9 (DR9 hereafter), with its extensive dataset of galaxy locations and photometric redshifts, presents an opportunity to study baryon acoustic oscillations (BAOs) in the region covered by the ongoing spectroscopic survey with DESI.

Aims. We aim to investigate differences between different parts of the DR9 footprint. Furthermore, we want to measure the BAO scale for luminous red galaxies within them. Our selected redshift range of 0.6–0.8 corresponds to the bin in which a tension between DESI Y1 and eBOSS was found.

Methods. We calculated the anisotropic two-point correlation function in a modified binning scheme to detect the BAOs in DR9 data. We then used template fits based on simulations to measure the BAO scale in the imaging data.

Results. Our analysis reveals the expected correlation function shape in most of the footprint areas, showing a BAO scale consistent with Planck’s observations. Aside from identified mask-related data issues in the southern region of the South Galactic Cap, we find a notable variance between the different footprints.

Conclusions. We find that this variance is consistent with the difference between the DESI Y1 and eBOSS data, and it supports the argument that that tension is caused by sample variance. Additionally, we also uncovered systematic biases not previously accounted for in photometric BAO studies. We emphasize the necessity of adjusting for the systematic shift in the BAO scale associated with typical photometric redshift uncertainties to ensure accurate measurements.