KiDS-1000: Combined halo-model cosmology constraints from galaxy abundance, galaxy clustering and galaxy-galaxy lensing

Abstract

We present constraints on the flat $\hat{I}›$CDM cosmological model through a joint analysis of galaxy abundance, galaxy clustering and galaxy-galaxy lensing observables with the Kilo-Degree Survey. Our theoretical model combines a flexible conditional stellar mass function, to describe the galaxy-halo connection, with a cosmological N-body simulation-calibrated halo model to describe the non-linear matter field. Our magnitude-limited bright galaxy sample combines 9-band optical-to-near-infrared photometry with an extensive and complete spectroscopic training sample to provide accurate redshift and stellar mass estimates. Our faint galaxy sample provides a background of accurately calibrated lensing measurements. We constrain the structure growth parameter $S_8=\ddot{I}{ƒ}_8\sqrt{\hat{I}{\text{c◯}}_{\mathrm{m}}/0.3}=0.773_{-0.030}^{+0.028}$, and the matter density parameter $\hat{I}{\text{c◯}}_{\mathrm{m}}=0.290_{-0.017}^{+0.021}$. The galaxy-halo connection model adopted in the work is shown to be in agreement with previous studies. Our constraints on cosmological parameters are comparable to, and consistent with, joint $3\times 2\mathrm{pt}$ clustering-lensing analyses that additionally include a cosmic shear observable. This analysis therefore brings attention to the significant constraining power in the often-excluded non-linear scales for galaxy clustering and galaxy-galaxy lensing observables. By adopting a theoretical model that accounts for non-linear halo bias, halo exclusion, scale-dependent galaxy bias and the impact of baryon feedback, this work demonstrates the potential and a way forward to include non-linear scales in cosmological analyses. Varying the width of the satellite galaxy distribution with an additional parameter yields a strong preference for sub-Poissonian variance, improving the goodness of fit by 0.18 in reduced $\ddot{I}{‡}^2$ value compared to a fixed Poisson distribution.

25 pages, 16 figures, accepted for publication in A&A, v3 with updated figure from Corrigendum (https://www.aanda.org/articles/aa/full_html/2024/08/aa50702e-24/aa50702e-24.html, https://doi.org/10.1051/0004-6361/202450702e)