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 themerger 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.

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 [10.1093/mnras/stx2792].

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

Benitez-Llambay, Alejandro;
2018

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 themerger 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.
Articolo in rivista - Articolo scientifico
Dark matter; Galaxies: haloes; Gravitational lensing: strong; Methods: numerical;
English
2018
474
1
604
617
none
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 [10.1093/mnras/stx2792].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/396269
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