# ELUCID -- Exploring the Local Universe with the reConstructed Initial Density field. II: Reconstruction diagnostics, applied to numerical halo catalogs

## TL;DR

The paper evaluates a reconstruction technique for creating initial conditions in cosmological simulations, demonstrating its effectiveness in tracing massive halos and analyzing the temporal convergence of structures.

## Contribution

It introduces and tests a reconstruction diagnostic method applied to N-body simulations, enhancing the accuracy of initial condition reconstructions for the ELUCID project.

## Key findings

- Most massive halos are effectively traced from the same initial regions.
- Reconstruction quality depends on the smoothing parameter used.
- High mass halos converge at redshifts close to the reconstruction redshift.

## Abstract

The ELUCID project aims to build a series of realistic cosmological simulations that reproduce the spatial and mass distribution of the galaxies as observed in the Sloan Digital Sky Survey (SDSS). This requires powerful reconstruction techniques to create constrained initial conditions. We test the reconstruction method by applying it to several $N$-body simulations. We use 2 medium resolution simulations from each of which three additional constrained $N$-body simulations were produced. We compare the resulting friend of friend catalogs by using the particle indexes as tracers, and quantify the quality of the reconstruction by varying the main smoothing parameter. The cross identification method we use proves to be efficient, and the results suggest that the most massive reconstructed halos are effectively traced from the same Lagrangian regions in the initial conditions. Preliminary time dependence analysis indicates that high mass end halos converge only at a redshift close to the reconstruction redshift. This suggests that, for earlier snapshots, only collections of progenitors may be effectively cross-identified.