The DESI DR1 Peculiar Velocity Survey: growth rate measurements from galaxy and momentum correlation functions

TL;DR

This paper measures the growth rate of cosmic structure using velocity and galaxy density correlations from DESI DR1, validating models with mock data, and finds results consistent with extit{Planck}+ extLambda CDM and general relativity.

Contribution

It introduces a novel joint analysis of velocity and density correlation functions to measure the growth rate, validated with mock catalogues, and provides a low-redshift growth index consistent with GR.

Findings

Measured $f\sigma_8 = 0.391^{+0.080}_{-0.081}$ from data

Combined analysis yields $f\sigma_8(z=0.07) = 0.4497 \pm 0.0548$

Measured gravitational growth index $\gamma_{L} = 0.580^{+0.110}_{-0.110}$

Abstract

Joint analysis of the local peculiar velocity and galaxy density fields offers a promising route to testing cosmological models of gravity. We present a measurement of the normalised growth rate of structure, $f\sigma_8$, from the two-point correlations of velocity and density tracers from the DESI DR1 Peculiar Velocity and Bright Galaxy Surveys, the largest catalogues of their kind assembled to date. We fit the two-point correlation measurements with non-linear correlation function models, constructed from density and momentum power spectra generated using 1-loop Eulerian perturbation theory, and validate our methodology using representative mock catalogues. We find $f\sigma_8 = 0.391^{+0.080}_{-0.081}$, consistent to within $1\sigma$ with accompanying analyses of the same datasets using power spectrum and maximum-likelihood fields methods. Combining these growth rate results from different methods including appropriate correlations, we find a consensus determination $f\sigma_8(z = 0.07) = 0.4497 \pm 0.0548$, consistent with predictions from \textit{Planck}$+\Lambda$CDM cosmology. Jointly fitting to this consensus low-redshift growth rate and the DESI DR1 full-shape clustering dataset, we measure gravitational growth index $\gamma_{\rm L} = 0.580^{+0.110}_{-0.110}$, consistent with the prediction of general relativity.