CMB lensing imprints of cosmic voids in DESI Legacy Survey DR9 LRGs with photometric redshift calibration

TL;DR

This study measures the CMB lensing imprint of cosmic voids in the DESI Legacy Survey, finding full agreement with ΛCDM predictions and resolving previous lensing tension reports.

Contribution

It provides the first detailed comparison of observed and simulated CMB lensing signals of cosmic voids, using calibrated mocks to confirm ΛCDM consistency.

Findings

Full agreement between observations and ΛCDM simulations across all void types.

Detection of void lensing signals with approximately 17σ significance.

Measurement of an amplitude parameter A_κ close to unity, indicating no tension.

Abstract

The lensing imprint of cosmic voids in the Cosmic Microwave Background (CMB) provides a powerful test of the $\Lambda$CDM model. However, recent studies report a "lensing-is-low" tension between observations and mock predictions. To investigate this, we measure the stacked CMB lensing signal of 3D cosmic voids identified in the DESI Legacy Survey DR9 Luminous Red Galaxy (LRG) sample, cross-correlated with the Planck 2018 lensing map. We compare our observations to $\Lambda$CDM templates derived from Buzzard mocks, critically calibrated using over one million DESI spectra to perfectly match the sparseness and photometric redshift error distributions of the observed data. By categorizing voids based on their gravitational potential, we disentangle the signals of void-in-voids and void-in-clouds, achieving two independent record detection significances of $\sim 17\sigma$. We find full agreement between observations and simulated $\Lambda$CDM templates across all void populations and redshift bins ($0.35\! <\! z\! <\! 0.95$), measuring an amplitude parameter $A_\kappa = 1.016 \pm 0.054$ for the full sample. This highlights the necessity of accurate systematic control, effectively resolving the reported lensing tension within this dataset. This proceeding summarizes the results presented in Sartori et al. (2025).