DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

• DOI: 10.60692/tqmep-ypq66
• Publication Date: 2023-05-26
• Authors: ChangHoon Hahn; M. J. Wilson; Omar Ruiz-Macias; Shaun Cole; David H. Weinberg; John Moustakas; Anthony Kremin; Jeremy L. Tinker; Alex Smith; Risa H. Wechsler; S. P. Ahlen; Shadab Alam; S. Bailey; D. Brooks; Andrew P. Cooper; Tamara M. Davis; Kyle Dawson; Arjun Dey; Biprateep Dey; Sarah Eftekharzadeh; Daniel J. Eisenstein; Kevin Fanning; Jaime E. Forero-R...; Carlos S. Frenk; E. Gaztañaga; Satya Gontcho A G...; J. Guy; K. Honscheid; Mustapha Ishak; Stéphanie Juneau; R. Kehoe; T. S. Kisner; Ting-Wen Lan; Martin Landriau; L. Le Guillou; M. E. Levi; Christophe Magnev...; Paul Martini; Aaron M. Meisner; Adam D. Myers; Jundan Nie; Peder Norberg; N. Palanque‐Delab...; Will J. Percival; Claire Poppett; Francisco Prada; Anand Raichoor; Ashley J. Ross; Sasha Safonova; Christoph Saulder; Edward F. Schlafly; David J. Schlegel; D. Sierra-Porta; G. Tarlé; B. A. Weaver; Ch Yèche; Pauline Zarrouk; Rongpu Zhou; Zhimin Zhou; Hu Zou
• Keywords: Observational cosmology; Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astronomy; FOS: Physical sciences; QB1-991; Stellar Astrophysics and Exoplanet Studies; Astrophysics; 7. Clean energy; 01 natural sciences; Spectro photometry; Astronomical Instrumentation and Spectroscopy; 0103 physical sciences; Dark energy; Galactic and extragalactic astronomy; Instrumentation; Telescope; Redshift surveys; LEMB; Spectrograph; Galaxy Formation and Evolution in the Universe; Physics; Astronomy and Astrophysics; Redshift; Galaxies; Astrophysics - Astrophysics of Galaxies; 520; Cosmology; Galaxy; Physics and Astronomy; Galaxy spectroscopy; Astrophysics of Galaxies (astro-ph.GA); Physical Sciences; Observatory; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Astrophysics - Cosmology and Nongalactic Astrophysics

Abstract Over the next 5 yr, the Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on the 4 m Mayall Telescope at Kitt Peak National Observatory to conduct the first Stage IV dark energy galaxy survey. At z < 0.6, the DESI Bright Galaxy Survey (BGS) will produce the most detailed map of the universe during the dark-energy-dominated epoch with redshifts of >10 million galaxies spanning 14,000 deg2. In this work, we present and validate the final BGS target selection and survey design. From the Legacy Surveys, BGS will target an r < 19.5 mag limited sample (BGS Bright), a fainter 19.5 < r < 20.175 color-selected sample (BGS Faint), and a smaller low-z quasar sample. BGS will observe these targets using exposure times scaled to achieve homogeneous completeness and cover the footprint three times. We use observations from the Survey Validation programs conducted prior to the main survey along with simulations to show that BGS can complete its strategy and make optimal use of “bright” time. BGS targets have stellar contamination <1%, and their densities do not depend strongly on imaging properties. BGS Bright will achieve >80% fiber assignment efficiency. Finally, BGS Bright and BGS Faint will achieve >95% redshift success over any observing condition. BGS meets the requirements for an extensive range of scientific applications. BGS will yield the most precise baryon acoustic oscillation and redshift-space distortion measurements at z < 0.4. It presents opportunities for new methods that require highly complete and dense samples (e.g., N-point statistics, multitracers). BGS further provides a powerful tool to study galaxy populations and the relations between galaxies and dark matter.