Nonlinear redshift-space distortions (“fingers of God”) are challenging to model analytically, a fact that limits the applicability of perturbation theory (PT) in redshift space as compared to real space. We show how this problem can be mitigated using a new observable, $Q_0$, which can be easily estimated from the redshift-space clustering data and is approximately equal to the real-space power spectrum. The new statistic does not suffer from fingers of God and can be accurately described with PT down to $k_{\max }\simeq 0.4h{\mathrm{Mpc}}^{-1}$. It can be straightforwardly included in the likelihood at negligible additional computational cost and yields noticeable improvements on cosmological parameters compared to standard power spectrum multipole analyses. Using both simulations and observational data from the Baryon Oscillation Spectroscopic Survey, we show that improvements vary from 10% to 100% depending on the cosmological parameter considered, the galaxy sample, and the survey volume.

• Received 14 October 2021
• Accepted 27 January 2022

DOI:https://doi.org/10.1103/PhysRevD.105.043531

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society