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Constructing high-fidelity halo merger trees in abacussummit

Bose, Sownak; Eisenstein, Daniel J; Hadzhiyska, Boryana; Garrison, Lehman H; Yuan, Sihan

Constructing high-fidelity halo merger trees in abacussummit Thumbnail


Daniel J Eisenstein

Boryana Hadzhiyska

Lehman H Garrison

Sihan Yuan


Tracking the formation and evolution of dark matter haloes is a critical aspect of any analysis of cosmological N-body simulations. In particular, the mass assembly of a halo and its progenitors, encapsulated in the form of its merger tree, serves as a fundamental input for constructing semi-analytic models of galaxy formation and, more generally, for building mock catalogues that emulate galaxy surveys. We present an algorithm for constructing halo merger trees from ABACUSSUMMIT, the largest suite of cosmological N-body simulations performed to date consisting of nearly 60 trillion particles, and which has been designed to meet the Cosmological Simulation Requirements of the Dark Energy Spectroscopic Instrument (DESI) survey. Our method tracks the cores of haloes to determine associations between objects across multiple time slices, yielding lists of halo progenitors and descendants for the several tens of billions of haloes identified across the entire suite. We present an application of these merger trees as a means to enhance the fidelity of ABACUSSUMMIT halo catalogues by flagging and ‘merging’ haloes deemed to exhibit non-monotonic past merger histories. We show that this cleaning technique identifies portions of the halo population that have been deblended due to choices made by the halo finder, but which could have feasibly been part of larger aggregate systems. We demonstrate that by cleaning halo catalogues in this post-processing step, we remove potentially unphysical features in the default halo catalogues, leaving behind a more robust halo population that can be used to create highly accurate mock galaxy realizations from ABACUSSUMMIT.


Bose, S., Eisenstein, D. J., Hadzhiyska, B., Garrison, L. H., & Yuan, S. (2022). Constructing high-fidelity halo merger trees in abacussummit. Monthly Notices of the Royal Astronomical Society, 512(1), 837-854.

Journal Article Type Article
Acceptance Date Feb 24, 2022
Online Publication Date Mar 3, 2022
Publication Date 2022-05
Deposit Date May 27, 2022
Publicly Available Date May 27, 2022
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 512
Issue 1
Pages 837-854


Published Journal Article (3.2 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2022 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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