Cosmology from Planck CMB Lensing and DESI DR1 Quasar Tomography

R. de Belsunce, A. Krolewski, S. Chiarenza, E. Chaussidon, S. Ferraro, B. Hadzhiyska, C. Ravoux, N. Sailer, G. Farren, A. Tamone, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, J. Della Costa, Biprateep Dey, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, H. K. Herrera-Alcantar, K. Honscheid, M. Ishak, R. Joyce, S. Juneau, R. Kehoe, D. Kirkby, T. Kisner, A. Kremin, O. Lahav, A. Lambert, C. Lamman, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, P. Martini, A. Meisner, R. Miquel, S. Nadathur, G. Niz, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, A. J. Ross, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, R. Zhou, H. Zou

First listed 2025-06-27 | Last updated 2025-06-27

Abstract

We present a measurement of the amplitude of matter fluctuations over the redshift range 0.8 <= z <= 3.5 from the cross correlation of over 1.2 million spectroscopic quasars selected by the Dark Energy Spectroscopic Instrument (DESI) across 7,200 deg$^2$ (approx 170 quasars/deg$^2$) and Planck PR4 (NPIPE) cosmic microwave background (CMB) lensing maps. We perform a tomographic measurement in three bins centered at effective redshifts z=1.44, 2.27 and 2.75, which have ample overlap with the CMB lensing kernel. From a joint fit using the angular clustering of all three redshift bins (auto and cross-spectra), and including an $Ω_m$ prior from DESI DR1 baryon acoustic oscillations to break the $Ω_m-σ_8$ degeneracy, we constrain the amplitude of matter fluctuations in the matter-dominated regime to be $σ_8=0.929^{+0.059}_{-0.074}$ and $S_8\equiv σ_8(Ω_m/0.3)^{0.5} = 0.922^{+0.059}_{-0.073}$. We provide a growth of structure measurement with the largest spectroscopic quasar sample to date at high redshift, which is 1.5$σ$ higher than predictions from $Λ$CDM fits to measurements of the primary CMB from Planck PR4. The cross-correlation between PR4 lensing maps and DESI DR1 quasars is detected with a signal-to-noise ratio of 21.7 and the quasar auto-correlation at 27.2 for the joint analysis of all redshift bins. We combine our measurement with the CMB lensing auto-spectrum from the ground-based Atacama Cosmology Telescope (ACT DR6) and Planck PR4 to perform a sound-horizon-free measurement of the Hubble constant, yielding $H_0=69.1^{+2.2}_{-2.6}\,\mathrm{km}\,\mathrm{s}^{-1}\mathrm{Mpc}^{-1}$ through its sensitivity to the matter-radiation equality scale.

Short digest

Cross-correlating Planck PR4 (NPIPE) CMB lensing maps with 1.22M DESI DR1 spectroscopic quasars over 7,200 deg², the authors perform three-bin quasar–lensing tomography at z≈1.44, 2.27, and 2.75. A joint fit to quasar auto- and quasar×lensing power spectra, with an Ωm prior from DESI DR1 BAO, yields σ8=0.929(+0.059/−0.074) and S8=0.922(+0.059/−0.073), with detections of the cross and auto signals at S/N=21.7 and 27.2, respectively. The inferred growth amplitude is ≈1.5σ higher than ΛCDM predictions from Planck primary CMB, providing a high‑z, matter‑era check on structure formation. Combining with the Planck PR4 and ACT DR6 lensing auto-spectra, they obtain a sound-horizon-free H0=69.1(+2.2/−2.6) km s⁻¹ Mpc⁻¹ via sensitivity to the matter–radiation equality scale.

Key figures to inspect

• Data maps: PR4 κ-convergence, DESI DR1 quasar density, and completeness mask—inspect sky overlap (Planck 67.1% vs DESI 20.3%) and spatial nonuniformities that could affect large-scale power.
• Tomographic Cℓ(κ×q) per bin at z≈1.44, 2.27, 2.75 with best-fit model—check scale dependence, ℓ-ranges used, and per-bin S/N driving the joint constraints.
• Quasar auto-power spectra and inferred bias vs redshift—verify consistency across bins and with mocks/analytic expectations used in the likelihood.
• Posterior contours for σ8/S8 with the DESI-BAO Ωm prior—see the ≈1.5σ preference relative to Planck primary-CMB ΛCDM and how the tomographic bins combine.
• Lensing-only H0 constraint figure (Planck PR4 + ACT DR6 autospectra plus this cross-correlation)—see how the equality-scale information yields H0 without a sound-horizon prior.