BAO reconstruction: A swift numerical action method for massive spectroscopic surveys

Abstract

A new fully non-linear reconstruction algorithm for the accurate recovery of the baryonic acoustic oscillations (BAO) scale in two-point correlation functions is proposed, based on the least action principle and extending the Fast Action Minimisation method by Nusser & Branchini (2000). Especially designed for massive spectroscopic surveys, it is tested on dark matter halo catalogues extracted from the deus-fur Lambda cold dark matter simulation (Reverdy et al.2015) to trace the trajectories of up to ∼sim 207, 000 haloes backward in time, well beyond the first-order Lagrangian approximation. The new algorithm successfully recovers the BAO feature in real and redshift space in both the monopole and the anisotropic two-point correlation function, also for anomalous samples showing misplaced or absent signature of BAO. In redshift space, the non-linear displacement parameter Σ NL is reduced from 11.8±0.3, h-1 Mpc at redshift z = 0 to 4.0±0.5, h-1 Mpc at z ≈ 37 after reconstruction. A comparison with the first-order Lagrangian reconstruction is presented, showing that these techniques outperform the linear approximation in recovering an unbiased measurement of the acoustic scale.