Galaxy clustering in the DESI Legacy Survey and its imprint on the CMB

We use data from the DESI Legacy Survey imaging to probe the galaxy density field in tomographic slices covering the redshift range 0 < z < 0.8. After careful consideration of completeness corrections and galactic cuts, we obtain a sample of 4.9 x 10(7) galaxies covering 17 739 deg(2). We derive photometric redshifts with precision sigma(z)/(1 + z) = 0.012-0.015, and compare with alternative estimates.(1) Cross-correlation of the tomographic galaxy maps with Planck maps of cosmic microwave background (CMB) temperature and lensing convergence probe the growth of structure since z = 0.8. The signals are compared with a fiducial Planck Lambda CDM model, and require an overall scaling in amplitude of A(kappa) = 0.901 +/- 0.026 for the lensing cross-correlation and AISW = 0.984 +/- 0.349 for the temperature cross-correlation, interpreted as the integrated Sachs-Wolfe effect. The ISW amplitude is consistent with the fiducial Lambda cold dark matter (Lambda CDM) prediction, but lies significantly below the prediction of the AvERA model of Racz et al., which has been proposed as an alternative explanation for cosmic acceleration. Within Lambda CDM, our low amplitude for the lensing cross-correlation requires a reduction either in fluctuation normalization or in matter density compared to the Planck results, so that Omega(0.78)(m) sigma(8) = 0.297 +/- 0.009. In combination with the total amplitude of CMB lensing, this favours a shift mainly in density: Omega(m) = 0.274 +/- 0.024. We discuss the consistency of this figure with alternative evidence. A conservative compromise between lensing and primary CMBconstraints would require Omega(m) = 0.296 +/- 0.006, where the 95 per cent confidence regions of both probes overlap.

Automated summary

Using data from the DESI Legacy Survey, research investigated the galaxy density field in tomographic slices covering the redshift range 0 < z < 0.8. Cross-correlation analysis of photometric redshifts and CMB maps revealed the growth of structure since z = 0.8. In the context of Lambda CDM, a reduction in fluctuation normalization or matter density was found to be necessary based on the results from lensing and CMB analysis.