Consistent and simultaneous modelling of galaxy clustering and galaxy–galaxy lensing with subhalo abundance matching

Abstract

ABSTRACT The spatial distribution of galaxies and their gravitational lensing signal offer complementary tests of galaxy formation physics and cosmology. However, their synergy can only be fully exploited if both probes are modelled accurately and consistently. In this paper, we demonstrate that this can be achieved using an extension of Sub-Halo Abundance Matching extended model (SHAMe), dubbed SHAMe. Specifically, we use mock catalogues built from the TNG300 hydrodynamical simulation to show that SHAMe can simultaneously model the multipoles of the redshift–space galaxy correlation function and galaxy–galaxy lensing, without noticeable bias within the statistical sampling uncertainties of a SDSS volume and on scales r ∈ [0.6 − 30]h−1 Mpc. Modelling the baryonic processes in galaxy–galaxy lensing with a baryonification scheme allows SHAMe’s range of validity to be extended to r ∈ [0.1 − 30] h−1 Mpc. Remarkably, our model achieves this level of precision with just five free parameters beyond those describing the baryonification model. At fixed cosmology, we find that galaxy–galaxy lensing provides a general consistency test but little additional information on galaxy modelling parameters beyond that encoded in the redshift-space multipoles. It does, however, improve constraints if only the projected correlation function is available, as in surveys with only photometric redshifts. We expect SHAMe to have a higher fidelity across a wider range of scales than more traditional methods such as Halo Occupation Distribution modelling. Thus it should provide a significantly more powerful and more robust tool for analysing next-generation large-scale surveys.