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HBT+: an improved code for finding subhaloes and building merger trees in cosmological simulations

Han, J.; Cole, S.; Frenk, C.S.; Benitez-Llambay, A.; Helly, J.

HBT+: an improved code for finding subhaloes and building merger trees in cosmological simulations Thumbnail


Authors

J. Han

A. Benitez-Llambay

J. Helly



Abstract

Dark matter subhalos are the remnants of (incomplete) halo mergers. Identifying them and establishing their evolutionary links in the form of merger trees is one of the most important applications of cosmological simulations. The HBT (Hierachical Bound-Tracing) code identifies haloes as they form and tracks their evolution as they merge, simultaneously detecting subhaloes and building their merger trees. Here we present a new implementation of this approach, HBT+ , that is much faster, more user friendly, and more physically complete than the original code. Applying HBT+ to cosmological simulations, we show that both the subhalo mass function and the peak-mass function are well fitted by similar double-Schechter functions. The ratio between the two is highest at the high-mass end, reflecting the resilience of massive subhaloes that experience substantial dynamical friction but limited tidal stripping. The radial distribution of the most-massive subhaloes is more concentrated than the universal radial distribution of lower mass subhaloes. Subhalo finders that work in configuration space tend to underestimate the masses of massive subhaloes, an effect that is stronger in the host centre. This may explain, at least in part, the excess of massive subhaloes in galaxy cluster centres inferred from recent lensing observations. We demonstrate that the peak-mass function is a powerful diagnostic of merger tree defects, and the merger trees constructed using HBT+ do not suffer from the missing or switched links that tend to afflict merger trees constructed from more conventional halo finders. We make the HBT+ code publicly available.

Citation

Han, J., Cole, S., Frenk, C., Benitez-Llambay, A., & Helly, J. (2018). HBT+: an improved code for finding subhaloes and building merger trees in cosmological simulations. Monthly Notices of the Royal Astronomical Society, 474(1), 604-617. https://doi.org/10.1093/mnras/stx2792

Journal Article Type Article
Acceptance Date Oct 23, 2017
Online Publication Date Oct 26, 2017
Publication Date Feb 11, 2018
Deposit Date Jan 15, 2018
Publicly Available Date Mar 29, 2024
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 474
Issue 1
Pages 604-617
DOI https://doi.org/10.1093/mnras/stx2792

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2017. The Authors.
Published by Oxford University Press on behalf of the Royal Astronomical Society.





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