Cross-Correlation between Damped Ly-alpha Systems and Ly-break Galaxies in Cosmological SPH Simulations

TL;DR

This study uses cosmological hydrodynamic simulations to analyze the spatial correlation between damped Ly-alpha systems and Lyman break galaxies at redshift 3, confirming their distribution aligns with the Lambda CDM model and matches observations.

Contribution

It introduces two methods for calculating the cross-correlation function between DLAs and LBGs, including a cross-section-weighted approach, and compares results with observational data.

Findings

Simulation results agree with observational measurements.

LBGs and DLAs are well described by the Lambda CDM model.

Correlation strengths are consistent with observations, higher than low-mass merger models.

Abstract

We calculate the cross-correlation function (CCF) between damped Ly-a systems (DLAs) and Lyman break galaxies (LBGs) using cosmological hydrodynamic simulations at z=3. We compute the CCF with two different methods. First, we assume that there is one DLA in each dark matter halo if its DLA cross section is non-zero. In our second approach we weight the pair-count by the DLA cross section of each halo, yielding a cross-section-weighted CCF. We also compute the angular CCF for direct comparison with observations. Finally, we calculate the auto-correlation functions of LBGs and DLAs, and their bias against the dark matter distribution. For these different approaches, we consistently find that there is good agreement between our simulations and observational measurements by Cooke et al. and Adelberger et al. Our results thus confirm that the spatial distribution of LBGs and DLAs can be well described within the framework of the concordance Lambda CDM model. We find that the correlation strengths of LBGs and DLAs are consistent with the actual observations, and in the case of LBGs it is higher than would be predicted by low-mass galaxy merger models.