The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: a large sample of mock galaxy catalogues

TL;DR

This paper introduces a rapid method for generating large sets of mock galaxy catalogues using 2LPT and HOD models, enabling accurate covariance estimation and analysis testing for large-scale galaxy surveys.

Contribution

The authors develop a fast, calibrated approach to produce realistic mock galaxy catalogues that match clustering and covariance properties of actual survey data.

Findings

Clustering of halos is recovered within ~10% accuracy.

600 mock catalogues created for BOSS Data Release 9.

Method effectively reproduces covariance matrices and supports analysis validation.

Abstract

We present a fast method of producing mock galaxy catalogues that can be used to compute covariance matrices of large-scale clustering measurements and test the methods of analysis. Our method populates a 2nd-order Lagrangian Perturbation Theory (2LPT) matter field, where we calibrate masses of dark matter halos by detailed comparisons with N-body simulations. We demonstrate the clustering of halos is recovered at ~10 per cent accuracy. We populate halos with mock galaxies using a Halo Occupation Distribution (HOD) prescription, which has been calibrated to reproduce the clustering measurements on scales between 30 and 80 Mpc/h. We compare the sample covariance matrix from our mocks with analytic estimates, and discuss differences. We have used this method to make catalogues corresponding to Data Release 9 of the Baryon Oscillation Spectroscopic Survey (BOSS),producing 600 mock catalogues of the "CMASS" galaxy sample. These mocks enabled detailed tests of methods and errors that formed an integral part of companion analyses of these galaxy data.