We present measurements of the redshift-dependent clustering of a DESI-like luminous red galaxy (LRG) sample selected from the Legacy Survey imaging dataset, and use the halo occupation distribution (HOD) framework to fit the clustering signal. The photometric LRG sample in this study contains 2.7 million objects over the redshift range of 0.4 < z < 0.9 over 5655 sq. degrees. We have developed new photometric redshift (photo-z) estimates using the Legacy Survey DECam and WISE photometry, with σNMAD = 0.02 precision for LRGs. We compute the projected correlation function using new methods that maximize signal-to-noise while incorporating redshift uncertainties. We present a novel algorithm for dividing irregular survey geometries into equal-area patches for jackknife resampling. For a 5-parameter HOD model fit using the MultiDark halo catalog, we find that there is little evolution in HOD parameters except at the highest-redshifts. The inferred large-scale structure bias is largely consistent with constant clustering amplitude over time. In an appendix, we explore limitations of MCMC fitting using stochastic likelihood estimates resulting from applying HOD methods to N-body catalogs, and present a new technique for finding best-fit parameters in this situation. Accompanying this paper we have released the PRLS (Photometric Redshifts for the Legacy Surveys) catalog of photo-z’s obtained by applying the methods used in this work to the full Legacy Survey Data Release 8 dataset. This catalog provides accurate photometric redshifts for objects with z < 21 over more than 16,000 square degrees of sky.

We use luminous red galaxies selected from the imaging surveys that are being used for targeting by the Dark Energy Spectroscopic Instrument (DESI) in combination with CMB lensing maps from the Planck collaboration to probe the amplitude of large-scale structure over 0.4 ≤ z ≤ 1. Our galaxy sample, with an angular number density of approximately 500 deg-2 over 18,000 sq.deg., is divided into 4 tomographic bins by photometric redshift and the redshift distributions are calibrated using spectroscopy from DESI. We fit the galaxy autospectra and galaxy-convergence cross-spectra using models based on cosmological perturbation theory, restricting to large scales that are expected to be well described by such models. Within the context of ΛCDM, combining all 4 samples and using priors on the background cosmology from supernova and baryon acoustic oscillation measurements, we find S 8 = σ8(Ωm/0.3)0.5 = 0.73 ± 0.03. This result is lower than the prediction of the ΛCDM model conditioned on the Planck data. Our data prefer a slower growth of structure at low redshift than the model predictions, though at only modest significance.

BigBOSS: The Ground-Based Stage IV BAO ExperimentThis Response to the Decadal Survey is submitted by:The Lawrence Berkeley National Laboratory 1 Cyclotron Rd MS 50R-5032, Berkeley, CA 94720 David Schlegel, DJSchlegel@lbl.gov, 510-495-2595 Chris EXECUTIVE SUMMARYThe BigBOSS experiment is a proposed DOE-NSF Stage IV ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with an allsky galaxy redshift survey. The project is designed to unlock the mystery of dark energy using existing ground-based facilities operated by NOAO. A new 4000-fiber R=5000 spectrograph covering a 3-degree diameter field will measure BAO and redshift space distortions in the distribution of galaxies and hydrogen gas spanning redshifts from 0.2 < z < 3.5. The Dark Energy Task Force figure of merit (DETF FoM) for this experiment is expected to be equal to that of a JDEM mission for BAO with the lower risk and cost typical of a ground-based experiment. This project will enable an unprecedented multi-object spectroscopic capability for the U.S. community through an existing NOAO facility. The U.S. community would have access directly to this instrument/telescope combination, as well as access to the legacy archives that will be created by the BAO key project.The BigBOSS survey will target luminous red galaxies, emission line galaxies, and QSOs. This experiment builds upon the SDSS-III/BOSS project, reusing many aspects of the BOSS spectrograph and computing pipeline designs. The BigBOSS project is enabled by the impressive 3 degree diameter field of view of the 4-m Mayall telescope at KPNO. The focal plane of this telescope will be filled with an automated fiber-positioner capable of targeting 4000 objects simultaneously over a wavelength range from 340 nm to 1130 nm with resolution R=2300-6100. This carefully-designed instrument is capable of measuring redshifts to the brightest [OII] emitters to z=2 with a 4-m aperture. Assuming a majority allocation of the dark time and optimal observing conditions during 30% of all nights, and with approximately onehour exposures, over 5 million targets will be visited per year. We propose to operate for six years at KPNO and then move the instrument to CTIO, the Mayall sister telescope in the southern hemisphere, for a four year run commencing after the Dark Energy Survey (DES) program.The 30-million galaxy sample of BigBOSS-North provides precision baryon acoustic oscillation measurements over 14000 square degrees from 0.2 < z < 2.0 and a million QSOs from 1.8< z <3.5. A continuation with BigBOSS-South completes the survey, bringing the total to 50 million galaxies over 24000 square degrees. BigBOSS will sculpt the redshift distribution to maximize the statistical significance of the dark energy measurement. The target selection will be done using existing and planned imaging surveys. A summary of experiment goals is shown in Table 1.BigBOSS is proposed as a partnership between NSF/NOAO and DOE/OHEP. Details of this partnership will be determined w...

We present the status of the Dark Energy Spectroscopic Instrument (DESI) and its plans and opportunities for the coming decade. DESI construction and its initial five years of operations are an approved experiment of the U.S. Department of Energy and is summarized here as context for the Astro2020 panel. Beyond 2025, DESI will require new funding to continue operations. We expect that DESI will remain one of the world's best facilities for wide-field spectroscopy throughout the decade. More about the DESI instrument and survey can be found at https://www.desi.lbl.gov.

The DESI survey will measure large-scale structure using quasars as direct tracers of dark matter in the redshift range 0.9 < z < 2.1 and using quasar Lyα forests at z > 2.1. We present two methods to select candidate quasars for DESI based on imaging in three optical (g, r, z) and two infrared (W1, W2) bands. The first method uses traditional color cuts and the second utilizes a machine-learning algorithm.