The MultiTracer Optimal Estimator applied to VIPERS
Abstract
We use mock galaxy data from the VIMOS Public Extragalactic Redshift Survey (VIPERS) to test the performance of the MultiTracer Optimal Estimator (MTOE) of Abramo et al. as a tool to measure the monopoles of the power spectra of multiple tracers of the largescale structure, P^{(0)}_α (k). We show that MTOE provides more accurate measurements than the standard technique of Feldman, Kaiser & Peacock (FKP), independently of the tracerselection strategy adopted, on both small and large scales. The largest improvements on individual P^{(0)}_α (k) are obtained on small scales, using a colourmagnitude selection, due to MTOE being naturally better equipped to deal with shot noise: we report an average error reduction with respect to FKP of ∼ 30 per cent at 0.3 < k [h Mpc^{1}] < 0.5, with improvements exceeding 4050 per cent for some tracers. On large scales (k[h Mpc^{1}] ≲ 0.1), the gain in accuracy resulting from cosmicvariance cancellation is ∼10 per cent for the ratios of P^{(0)}_α (k). We have carried out a Markov chain Monte Carlo analysis to determine the impact of these gains on several quantities derived from P^{(0)}_α (k). If we pushthat the estimated power spectra are themselves the measurement to scales 0.3 < k [h Mpc^{1}] < 0.5, the average improvements are ∼ 30 per cent for the amplitudes of the monopoles, ∼ 75 per cent for the monopole ratios, and ∼ 20 per cent for the linear galaxy biases. Our results highlight the potential of MTOE to shed light upon the physics that operate both on large and small cosmological scales. The effect of MTOE on cosmological constraints using VIPERS data will be addressed in a separate paper.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 April 2020
 DOI:
 10.1093/mnras/staa405
 arXiv:
 arXiv:1909.00010
 Bibcode:
 2020MNRAS.493.5257M
 Keywords:

 methods: data analysis;
 surveys;
 galaxies: haloes;
 cosmological parameters;
 largescale structure of Universe;
 cosmology: observations;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 19 pages, 13 figures