KiDS-1000: Combined halo-model cosmology constraints from galaxy abundance, galaxy clustering, and galaxy-galaxy lensing
Andrej Dvornik, Catherine Heymans, Marika Asgari, Constance Mahony, Benjamin Joachimi, Maciej Bilicki, Elisa Chisari, H. Hildebrandt, Henk Hoekstra, H. H. JOHNSTON, Konrad Kuijken, Alexander Mead, Hironao Miyatake, Takahiro Nishimichi, Robert Reischke, Sandra Unruh, Angus H. Wright
Abstract
We present constraints on the flat Λ cold dark matter 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, which describes the galaxy-halo connection, with a cosmological N -body simulation-calibrated halo model, which describes the non-linear matter field. Our magnitude-limited bright galaxy sample combines nine-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 to S 8 = σ 8 √Ω m /0.3 =√0.773 −0.030 +0.028 and the matter density parameter to Ω 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 × 2pt’ 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 for, and a way towards, including 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 terms of the reduced χ 2 value (and increasing the p -value by 0.25) compared to a fixed Poisson distribution.