Cosmological constraints from the redshift dependence of the Alcock-Paczynski effect: Fourier space analysis

TL;DR

This paper explores the feasibility of using Fourier space analysis of the redshift evolution of the Alcock-Paczynski effect to constrain cosmological parameters, demonstrating its robustness and advantages over traditional methods.

Contribution

It introduces a Fourier domain approach for the tomographic AP method, showing its effectiveness and advantages in cosmological parameter estimation.

Findings

Redshift evolution of AP distortion exceeds RSD effects by a factor of 1.7-3.6.

The method performs well across the entire tested k-range (0.2-1.8 h/Mpc).

Halo bias changes have minimal impact (<5%) on the results.

Abstract

The tomographic Alcock-Paczynski (AP) method utilizes the redshift evolution of the AP distortion to place constraints on cosmological parameters. It has proved to be a robust method that can separate the AP signature from the redshift space distortion (RSD) effect, and deliver powerful cosmological constraints using the $\lesssim 40h^{-1}\ \rm Mpc$ clustering region. In previous works, the tomographic AP method was performed via the anisotropic 2-point correlation function statistic. In this work we consider the feasibility of conducting the analysis in the Fourier domain and examine the pros and cons of this approach. We use the integrated galaxy power spectrum (PS) as a function of direction, $\hat P_{\Delta k}(\mu)$, to quantify the magnitude of anisotropy in the large-scale structure clustering, and use its redshift variation to do the AP test. The method is tested on the large, high resolution Big-MultiDark Planck (BigMD) simulation at redshifts $z=0-1$, using the underlying true cosmology $\Omega_m=0.3071,\ w=-1$. Testing the redshift evolution of $\hat P_{\Delta k}(\mu)$ in the true cosmology and cosmologies deviating from the truth with $\delta \Omega_m=0.1,\ \delta w=0.3$, we find that the redshift evolution of the AP distortion overwhelms the effects created by the RSD by a factor of $\sim1.7-3.6$. We test the method in the range of $k\in(0.2,1.8)\ h\ \rm Mpc^{-1}$, and find that it works well throughout the entire regime. We tune the halo mass within the range $2\times 10^{13}$ to $10^{14}\ M_{\odot}$, and find that the change of halo bias results in $\lesssim 5 \%$ change in $\hat P_{\Delta k}(\mu)$, which is less significant compared with the cosmological effect. Our work shows that it is feasible to conduct the tomographic AP analysis in the Fourier space.