Multiprobe Cosmology from the Abundance of SPT Clusters and DES Galaxy Clustering and Weak Lensing

TL;DR

This paper combines cosmic shear, galaxy clustering, and cluster abundance data from SPT and DES to constrain cosmological parameters, demonstrating the power of multi-probe analysis in understanding the Universe's large-scale structure.

Contribution

It presents a joint analysis of multiple cosmological probes, accounting for shared systematics, to improve constraints on cosmological parameters and test models like $ u$CDM and wCDM.

Findings

Measured $oxed{ ext{} ext{Ω}_ ext{m}=0.300 extpm0.017}$ and $oxed{ ext{σ}_8=0.797 extpm0.026}$.

Found $S_8=0.796 extpm0.013$, slightly lower than Planck.

Set an upper limit on neutrino mass $oxed{ ext{∑}m_ u<0.25~ ext{eV}}$ at 95% confidence.

Abstract

Cosmic shear, galaxy clustering, and the abundance of massive halos each probe the large-scale structure of the Universe in complementary ways. We present cosmological constraints from the joint analysis of the three probes, building on the latest analyses of the lensing-informed abundance of clusters identified by the South Pole Telescope (SPT) and of the auto- and cross-correlation of galaxy position and weak lensing measurements (3$\times$2pt) in the Dark Energy Survey (DES). We consider the cosmological correlation between the different tracers and we account for the systematic uncertainties that are shared between the large-scale lensing correlation functions and the small-scale lensing-based cluster mass calibration. Marginalized over the remaining $\Lambda$ cold dark matter ($\Lambda$CDM) parameters (including the sum of neutrino masses) and 52 astrophysical modeling parameters, we measure $\Omega_\mathrm{m}=0.300\pm0.017$ and $\sigma_8=0.797\pm0.026$. Compared to constraints from Planck primary cosmic microwave background (CMB) anisotropies, our constraints are only 15% wider with a probability to exceed of 0.22 ($1.2\sigma$) for the two-parameter difference. We further obtain $S_8\equiv\sigma_8(\Omega_\mathrm{m}/0.3)^{0.5}=0.796\pm0.013$ which is lower than the Planck measurement at the $1.6\sigma$ level. The combined SPT cluster, DES 3$\times$2pt, and Planck datasets mildly prefer a nonzero positive neutrino mass, with a 95% upper limit $\sum m_\nu<0.25~\mathrm{eV}$ on the sum of neutrino masses. Assuming a $w$CDM model, we constrain the dark energy equation of state parameter $w=-1.15^{+0.23}_{-0.17}$ and when combining with Planck primary CMB anisotropies, we recover $w=-1.20^{+0.15}_{-0.09}$, a $1.7\sigma$ difference with a cosmological constant. The precision of our results highlights the benefits of multiwavelength multiprobe cosmology.