Towards precision cosmology with Voids x CMB correlations (I): Roman-Agora mock catalogs and pipeline validation

TL;DR

This paper develops and validates versatile mock galaxy catalogs for Roman Space Telescope surveys, emphasizing the importance of void statistics for cosmological analyses and introducing a novel analog matching technique.

Contribution

It introduces a flexible analog matching method for creating accurate mock catalogs and demonstrates the significance of void statistics in cosmological studies.

Findings

Analog matching with halo mass reproduces galaxy statistics effectively.

Matching galaxy clustering alone does not ensure accurate void properties.

Void statistics provide independent constraints on galaxy-halo connections.

Abstract

We construct and validate a set of multi-purpose mock galaxy catalogs designed to capture, to different degrees of accuracy, the main characteristics of the Nancy Grace Roman Space Telescope survey. These catalogs provide a foundation for void statistics and various CMB cross-correlation analyses. Our approach differs from traditional halo occupation or abundance matching methods by directly translating a reference mock catalog -- containing basic properties of the host halos -- into a new simulation (in our case Agora). This technique, which we call analog matching, assigns a halo counterpart in the new simulation to each reference galaxy through a nearest-neighbor search in a multi-dimensional parameter space. This space can include halo mass, environmental measures and other galaxy-specific attributes. By varying the composition of this parameter vector, we can generate catalogs of differing complexity and test how galaxy-halo prescriptions influence LSS statistics and CMB-related observables. We find that analog matching based on halo mass alone, or halo mass and galaxy-type indicators, successfully reproduces the expected Roman emission-line galaxy statistics. We also show that reproducing two-dimensional galaxy clustering does not guarantee consistent void properties. Our results highlight the importance of matching void statistics for improved mock accuracy, and demonstrate that measuring voids provides independent and sensitive constraints on galaxy-halo connections beyond the matter power spectrum. An important by-product of our setup is that it is fully general and can be applied to any combination of simulation and reference catalog, provided that the desired parameter space for both is specified. The resulting Roman-Agora mock catalogs offer a versatile resource for LSS x CMB studies and a benchmark for assessing the impact of mock accuracy on cosmological observables.