ACACIA: a new method to produce on-the-fly merger trees in the RAMSES code

Abstract

The implementation of ACACIA, a new algorithm to generate dark matter halo merger trees with the Adaptive Mesh Refinement (AMR) code RAMSES, is presented. The algorithm is fully parallel and based on the Message Passing Interface (MPI). As opposed to most available merger tree tools, it works on the fly during the course of the N body simulation. It can track dark matter substructures individually using the index of the most bound particle in the clump. Once a halo (or a sub-halo) merges into another one, the algorithm still tracks it through the last identified most bound particle in the clump, allowing to check at later snapshots whether the merging event was definitive, or whether it was only temporary, with the clump only traversing another one. The same technique can be used to track orphan galaxies that are not assigned to a parent clump anymore because the clump dissolved due to numerical over-merging. We study in detail the impact of various parameters on the resulting halo catalogues and corresponding merger histories. We then compare the performance of our method using standard validation diagnostics, demonstrating that we reach a quality similar to the best available and commonly used merger tree tools. As a proof of concept, we use our merger tree algorithm together with a parametrised stellar-mass-to-halo-mass relation and generate a mock galaxy catalogue that shows good agreement with observational data.

24 pages, 17 figures. Accepted 2021 November 15 by MNRAS

References in corpus (15)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Properties of galaxies reproduced by a hydrodynamic simulation
• Simulating cosmic structure formation with the GADGET-4 code
• Disruption of Dark Matter Substructure: Fact or Fiction?
• A fitting formula for the merger timescale of galaxies in hierarchical clustering
• Building Merger Trees from Cosmological N-body Simulations
• SubHaloes going Notts: The SubHalo-Finder Comparison Project
• Evidence for the inside-out growth of the stellar mass distribution in galaxy clusters since z~1
• Climbing Halo Merger Trees with TreeFrog
• Sussing Merger Trees : The Impact of Halo Merger Trees on Galaxy Properties in a Semi-Analytic Model
• Effects of large-scale environment on the assembly history of central galaxies
• Observing Merger Trees in a New Light
• Testing subhalo abundance matching from redshift-space clustering

Cited by in corpus (3)

• On the origin of surprisingly cold gas discs in galaxies at high redshift
• Constructing Merger Trees of Density Peaks Using Phase-Space Watershed Segmentation Algorithm
• The Formation of Dwarf Galaxy Disks