Joint cosmological fits to DESI-DR1 full-shape clustering and weak gravitational lensing in configuration space

TL;DR

This work delivers the first configuration-space 3×2pt-like cosmological analysis for DESI-DR1 by jointly fitting DESI clustering multipoles with three weak-lensing surveys (KiDS-1000, DES-Y3, HSC-Y3). It combines an EFT-based perturbative model for galaxy clustering with a VD∞ FoG damping approach, and a halo-model–inspired weak-lensing description, all run through a Gaussian-process–based configuration-space emulator and Bayesian inference. The addition of weak-lensing information tightens the amplitude-related parameters (σ_{12}, ln(10^{10}A_s)) by up to ~36% and improves linear bias constraints by ~15–20%, while maintaining consistency across lensing surveys and with Planck results for several parameters. The results are consistent with the companion Fourier-space analyses and highlight the value of cross-probe, same-sky analyses, though they also reveal projection effects in amplitude parameters and the need for improved mock validation including intrinsic alignments for fully robust inference.

Abstract

We present a joint $3\times2$-pt cosmological analysis of auto- and cross-correlations between the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1) Bright Galaxy Survey (BGS) and Luminous Red Galaxy (LRG) samples and overlapping shear measurements from the KiDS-1000, DES-Y3 and HSC-Y3 weak lensing surveys. We perform our analysis in configuration space and, in addition to the cosmic shear correlation functions for each weak lensing dataset, we fit the tangential shear of the weak lensing source galaxies around DESI lens galaxies. Finally, we make use of the anisotropic BGS and LRG clustering information by fitting the full shape of the two-point correlation function multipoles measured over the full DESI-DR1 footprint, presenting the first full-shape analysis of DESI measurements in configuration space. We find that the addition of weak lensing information serves to improve, with respect to the clustering-only case, the measurements of the power spectrum amplitude parameters $\ln(10^{10}A_{\rm{s}})$ and $σ_{12}$ by $15\%$ and $36\%$, respectively. It also improves measurements of the linear bias of the lens galaxies by $15-20\%$, depending on the tracer. Our results show excellent consistency, regardless of the weak lensing survey considered, and are furthermore consistent with a companion analysis that fits $3\times2$-pt correlations including DESI projected clustering measurements, as well as the results published by the weak lensing collaborations themselves. Our measured values for weak lensing amplitude are $S_{8}^{\mathrm{DESI\times HSC}}=0.787\pm0.020$, $S_{8}^{\mathrm{DESI\times DES}}=0.791\pm0.016$, $S_{8}^{\mathrm{DESI\times KiDS}}=0.771\pm0.017$, which are $1.9σ-2.9σ$ below the $S_8$ value preferred by Planck. Finally, our clustering-only results are in good agreement with the Fourier space full-shape analysis of all DESI tracers.

Figures (12)

• Figure 1: A cartoon representation of the different source and lens correlation statistics combined by this paper. We use datasets of the shapes of distant source galaxies in photometric redshift bins, obtained from deep imaging surveys, where these shapes are correlated by weak gravitational lensing. DESI maps out a sample of foreground lens galaxies with spectroscopic redshifts. Our analysis then combines correlations between the shapes of the source galaxies (cosmic shear, $\xi_+$ and $\xi_-$), correlations between the shapes of the source galaxies and positions of the lens galaxies (average tangential shear due to galaxy-galaxy lensing, $\gamma_t$), and the auto-correlation between the redshift-space positions of the lens galaxies (clustering multipoles, $\xi_\ell$). Whilst conventional "$3 \times 2$-pt" analyses use projected clustering statistics of the lenses, our study also includes the redshift-space distortion information present in the monopole and quadrupole, $\ell = \{ 0,2 \}$.
• Figure 2: Flat $\Lambda$CDM parameter constraints derived from fits to mock-mean measurements on Abacus lightcones. We present the constraints derived from fitting the DESI-like BGS and LRG clustering multipoles, $\xi_{0,2}$, as well as joint fits to $\xi_{\pm} + \gamma_{\rm{t}}$ measurements corresponding to auto- and cross-correlations between HSC-Y1, KiDS-1000, DES-Y3, and DESI mock data. We also show the constraints obtained from fits to mock DESI$\times$DES-Y3 measurements, $\xi_{0,2}+\xi_{\pm}+\gamma_{\rm{t}}$ (shear$\times$RSD).
• Figure 3: Flat $\Lambda$CDM parameter constraints derived from galaxy clustering two-point correlation function multipole measurements on Abacus lightcones, for different DESI-like tracers.
• Figure 4: Comparison of marginalised posterior contours for the amplitude parameters $\sigma_{12}$ and $\ln(10^{10}A_{\rm{s}})$ obtained by fitting a theory vector that corresponds to Abacus clustering and the actual mock clustering measurements. The star shows the maximum posterior value for the mock fits obtained by running Minuit minimiser.
• Figure 5: Flat $\Lambda$CDM constraints derived from joint clustering and weak lensing fits to mean measurements on Abacus lightcones. Here we compare the constraints obtained using the combination of DESI with different weak lensing surveys: HSC-Y1 (in brown), KiDS-1000 (in blue) and DES (in red).