Observing Merger Trees in a New Light

Abstract

Merger trees harvested from cosmological $N$-body simulations encode the assembly histories of dark matter halos over cosmic time, and are a fundamental component of semi-analytical models (SAMs) of galaxy formation. The ability to compare the tools used to construct merger trees, namely halo finders and tree building algorithms, in an unbiased and systematic manner is critical to assess the quality of merger trees. In this paper, we present the dendogram, a novel method to visualise merger trees, which provides a comprehensive characterisation of a halo's assembly history - tracking subhalo orbits, halo merger events, and the general evolution of halo properties. We show the usefulness of the dendogram as a diagnostic tool of merger trees by comparing halo assembly histories from a single $N$-Body simulation analysed with three different halo-finders -\textsc{VELOCIraptor}, \textsc{AHF} and \textsc{Rockstar} - and their associated tree-builders. Based on our analysis of the resulting dendograms, we highlight how they have been used to motivate improvements to \textsc{VELOCIraptor}. The dendogram software is publicly available online, at: https://github.com/rhyspoulton/MergerTree-Dendograms .

18 pages, 18 figures, accepted for publication in PASA

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Cited by in corpus (18)

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• Physical properties and evolution of (Sub-)millimeter selected galaxies in the galaxy formation simulation Shark
• Introducing a new, robust galaxy finder algorithm for simulations
• From Stellar Halos to Intracluster Light: the physics of the Intra-Halo Stellar Component in cosmological hydrodynamical simulations
• KiDS-Legacy calibration: unifying shear and redshift calibration with the SKiLLS multi-band image simulations
• The HI Velocity Function: a test of cosmology or baryon physics?
• The physical drivers of the atomic hydrogen-halo mass relation
• Unveiling the atomic hydrogen-halo mass relation via spectral stacking
• Constructing high-fidelity halo merger trees in AbacusSummit
• From rest-frame luminosity functions to observer-frame colour distributions: tackling the next challenge in cosmological simulations
• Forensic reconstruction of galaxy colour evolution and population characterisation
• Extreme Primordial Star Formation Enabled by High Redshift Quasars
• Extracting galaxy merger timescales I: Tracking haloes with WhereWolf and spinning orbits with OrbWeaver
• Multi-wavelength consensus of large-scale linear bias
• Extracting Galaxy Merger Timescales II: A new fitting formula
• ACACIA: a new method to produce on-the-fly merger trees in the RAMSES code