unWISE tomography of Planck CMB lensing

TL;DR

This paper uses unWISE galaxy data and Planck CMB lensing maps to perform tomographic cross-correlation, achieving high significance detection and providing insights into structure growth and cosmological parameters.

Contribution

It presents a novel analysis combining unWISE galaxy samples with Planck CMB lensing maps across three redshift bins, including magnification bias correction and null tests.

Findings

High significance cross-correlation (S/N=79.3) over multiple scales.

Redshift distributions of unWISE sources characterized through cross-matching and cross-correlation.

Magnification bias correction is essential for accurate results.

Abstract

CMB lensing tomography, or the cross-correlation between CMB lensing maps and large-scale structure tracers over a well-defined redshift range, has the potential to map the amplitude and growth of structure over cosmic time, provide some of the most stringent tests of gravity, and break important degeneracies between cosmological parameters. In this work, we use the unWISE galaxy catalog to provide three samples at median redshifts $z \sim 0.6, 1.1$ and 1.5, fully spanning the Dark Energy dominated era, together with the most recent Planck CMB lensing maps. We obtain a combined cross-correlation significance $S/N = 79.3$ over the range of scales $100 < \ell < 1000$. We measure the redshift distribution of unWISE sources by a combination of cross-matching with the COSMOS photometric catalog and cross-correlation with BOSS galaxies and quasars and eBOSS quasars. We also show that magnification bias must be included in our analysis and perform a number of null tests. In a companion paper, we explore the derived cosmological parameters by modeling the non-linearities and propagating the redshift distribution uncertainties.