Remapping simulated halo catalogues in redshift space

TL;DR

This paper extends a rescaling algorithm to redshift space, enabling accurate transformation of simulated halo catalogues across different cosmologies without tuning parameters, and demonstrates its effectiveness in reproducing key cosmological statistics.

Contribution

The paper adapts and validates a no-tuning rescaling method for halo catalogues in redshift space, improving its applicability for cosmological analyses.

Findings

Rescaling accurately reproduces the growth rate of density fluctuations.

Redshift-space power spectrum matches target cosmology within 5% for k<0.2h Mpc^-1.

Quadrupole-to-monopole ratio remains correct up to k=1h Mpc^-1 with velocity dispersions.

Abstract

We discuss the extension to redshift space of a rescaling algorithm, designed to alter the effective cosmology of a pre-existing simulated particle distribution or catalogue of dark matter haloes. The rescaling approach was initially developed by Angulo & White and was adapted and applied to halo catalogues in real space in our previous work. This algorithm requires no information other than the initial and target cosmological parameters, and it contains no tuned parameters. It is shown here that the rescaling method also works well in redshift space, and that the rescaled simulations can reproduce the growth rate of cosmological density fluctuations appropriate for the target cosmology. Even when rescaling a grossly non-standard model with Lambda=0 and zero baryons, the redshift-space power spectrum of standard LCDM can be reproduced to about 5% error for k<0.2h Mpc^-1. The ratio of quadrupole-to-monopole power spectra remains correct to the same tolerance up to k=1h Mpc^-1, provided that the input halo catalogue contains measured internal velocity dispersions.