A Galaxy-Halo Model for Multiple Cosmological Tracers

TL;DR

This paper introduces a new flexible galaxy-halo model that links dark matter halos to multiple galaxy tracers across different wavelengths, enhancing the analysis of large galaxy survey data.

Contribution

It develops a novel parametric model connecting halo properties to galaxy observables, enabling analytic calculations and efficient mock catalogues for multi-tracer cosmological studies.

Findings

Allows analytic halo model calculations for multiple tracers.

Provides semi-realistic galaxy properties for fast mock catalogues.

Facilitates cross-correlation analysis of galaxy survey data.

Abstract

The information extracted from large galaxy surveys with the likes of DES, DESI, Euclid, LSST, SKA, and WFIRST will be greatly enhanced if the resultant galaxy catalogues can be cross-correlated with one another. Predicting the nature of the information gain, and developing the tools to realise it, depends on establishing a consistent model of how the galaxies detected by each survey trace the same underlying matter distribution. Existing analytic methods, such as halo occupation distribution (HOD) modelling, are not well-suited for this task, and can suffer from ambiguities and tuning issues when applied to multiple tracers. In this paper, we take the first steps towards constructing an alternative that provides a common model for the connection between galaxies and dark matter halos across a wide range of wavelengths (and thus tracer populations). This is based on a chain of parametrised statistical distributions that model the connection between (a) halo mass and bulk physical properties of galaxies, such as star-formation rate; and (b) those same physical properties and a variety of emission processes. The result is a flexible parametric model that allows analytic halo model calculations of 1-point functions to be carried out for multiple tracers, as well as providing semi-realistic galaxy properties for fast mock catalogue generation.