Abstract 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 largescale 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 galaxyconvergence crossspectra 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 = σ 8 (Ω m /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.
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Cosmological constraints from unWISE and Planck CMB lensing tomography
Abstract A number of recent, lowredshift, lensing measurements hint at a universe in which the amplitude of lensing is lower than that predicted from the ΛCDM model fit to the data of the Planck CMB mission. Here we use the auto and crosscorrelation signal of unWISE galaxies and Planck CMB lensing maps to infer cosmological parameters at low redshift. In particular, we consider three unWISE samples (denoted as "blue", "green" and "red") at median redshifts z ∼ 0.6, 1.1 and 1.5, which fully cover the Dark Energy dominated era. Our crosscorrelation measurements, with combined significance S / N ∼ 80, are used to infer the amplitude of lowredshift fluctuations, σ 8 ; the fraction of matter in the Universe, Ω m ; and the combination S 8 ≡ σ 8 (Ω m /0.3) 0.5 to which these lowredshift lensing measurements are most sensitive. The combination of blue, green and red samples gives a value S m = 0.784 ± 0.015, that is fully consistent with other lowredshift lensing measurements and in 2.4σ tension with the CMB predictions from Planck. This is noteworthy, because CMB lensing probes the same physics as previous galaxy lensing measurements, but with very different systematics, thus providing an excellent complement to previous measurements.
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 Award ID(s):
 1713791
 NSFPAR ID:
 10322136
 Date Published:
 Journal Name:
 Journal of Cosmology and Astroparticle Physics
 Volume:
 2021
 Issue:
 12
 ISSN:
 14757516
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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