AMICO galaxy clusters in KiDS-1000: Cosmological constraints from the two-point correlation function

Abstract

In this paper we study the clustering properties of an optically identified photometric galaxy cluster catalogue from KiDS-1000. The sample was identified by the AMICO algorithm and consists of 9049 clusters with $S/N\geq3.5$, in the redshift range $0.1\leq z<0.8$, spread over an effective area of 838.78 deg$^2$. Clusters are selected according to their observed intrinsic richness, with thresholds of $λ^*{obs}\geq 20,25,30$ within $0.10\leq z<0.30$, $0.30\leq z<0.45$ and $0.45\leq z<0.80$, respectively. We measure the multipoles of the two-point correlation function over different ranges of scales from 5 $h^{-1}$ Mpc to 150 $h^{-1}$ Mpc. We model the clustering signal in the context of the $Λ$CDM cosmology, accounting for the main observational effects, such RSDs and photo-$z$ uncertainties. The effective bias of the cluster sample is estimated via a mass-richness scaling relation. For the MCMC analysis, we adopt Gaussian priors on the parameters of the mass-richness scaling relation, and broad, uniform priors to derive cosmological constraints on the cold matter density parameter, the power spectrum amplitude and the structure growth parameter, $S_8\equivσ_8 \sqrt{Ω{m}/0.3}$. Specifically, we find $Ω_{m}=0.24^{+0.02}{-0.02}$ and $σ_8=0.86^{+0.13}{-0.10}$ representing an improvement in precision over both the 2D and 3D AMICO clustering analyses performed on the previous KiDS data release. Moreover, we obtain $S_8=0.77^{+0.10}_{-0.08}$ in $1σ$ agreement with the AMICO KiDS-1000 number counts constraints estimated from the same catalogue, as well as with some results from external early- and late-Universe data sets. Our work strengthens the potential of cluster clustering as a complementary and competitive probe, to be included and further developed with the final KiDS-Legacy data release, and in other future Stage-IV photometric redshift surveys.