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We compare subhalo mass and velocity functions obtained from different simulations with different subhalo finders among each other, and with predictions from the new semi-analytical model of Jiang & van den Bosch (2014). We find that…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-28 Frank C. van den Bosch , Fangzhou Jiang

Multiresolution analysis is applied to the problem of halo identification in cosmological N-body simulations. The procedure makes use of a discrete wavelet transform known as the algorithme a trous and segmentation analysis. It has the…

Astrophysics · Physics 2009-10-31 Michael D. Seymour , Lawrence M. Widrow

We identify shell-like tidal structures in flattened haloes that appear stream-like under different projections. This projection dependence demonstrates how changes in the host halo directly impact the formation and classification of tidal…

Astrophysics of Galaxies · Physics 2026-04-09 Smrithi Gireesh Babu , Viraj Ekanayaka , William H. Oliver , Geraint F. Lewis

The cosmic web consists of a nested hierarchy of structures: voids, walls, filaments, and clusters. These structures interconnect and can encompass one another, collectively shaping an intricate network. Here we introduce the Hierarchical…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-31 M. A. Aragon-Calvo

Weak lensing three-point statistics are powerful probes of the structure of dark matter halos. We propose to use the correlation of the positions of galaxies with the shapes of background galaxy pairs, known as the halo-shear-shear…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-07 Masato Shirasaki , Naoki Yoshida

We introduce a new halo/subhalo finder, HIKER (a Halo fInder based on KERnel-shift algorithm), which takes advantage of a machine learning method -- the mean-shift algorithm combined with the Plummer kernel function, to effectively locate…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-06 Shuangpeng Sun , Shihong Liao , Qi Guo , Qiao Wang , Liang Gao

This paper reviews and analyses methods used to identify neighbours in 6D space and estimate the corresponding phase-space density. It compares SPH methods to 6D Delaunay tessellation on statical and dynamical realisation of single halo…

Astrophysics · Physics 2009-11-13 M. Maciejewski , S. Colombi , C. Alard , F. Bouchet , C. Pichon

The shapes of individual self-gravitating structures of an ensemble of identical, collisionless particles have remained elusive for decades. In particular, a reason why mass density profiles like the Navarro-Frenk-White or the Einasto…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-01 Jenny Wagner

We report the results of the first study of the multi-stream environment of dark matter haloes in cosmological N-body simulations in the LCDM cosmology. The full dynamical state of dark matter can be described as a three-dimensional…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-22 Nesar S. Ramachandra , Sergei F. Shandarin

We propose a new numerical procedure to simulate a single dark halo of any size and mass in a hierarchical framework coupling the extended Press-Schechter formalism (EPSF) to N-body simulations. The procedure consists of assigning…

Astrophysics · Physics 2009-11-07 Elena D'Onghia , Claudio Firmani , Guido Chincarini

We investigate hierarchical mergers among subhalos within a $\Lambda$CDM simulation using the HBT+ subhalo finder. Unlike previous methods, HBT+ tracks subhalo evolution across hierarchy levels, identifying the coalescence of subhalo cores…

A new analysis method to investigate halos in finite many-fermion systems is designed, as existing characterization methods are proven to be incomplete/inaccurate. A decomposition of the internal wave-function of the {$N$-body} system in…

Nuclear Theory · Physics 2013-05-29 V. Rotival , T. Duguet

We present a detailed comparison of the substructure properties of a single Milky Way sized dark matter halo from the Aquarius suite at five different resolutions, as identified by a variety of different (sub-)halo finders for simulations…

We present a new method to identify large scale filaments and apply it to a cosmological simulation. Using positions of haloes above a given mass as node tracers, we look for filaments between them using the positions and masses of all the…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-22 Roberto E. Gonzalez , Nelson E. Padilla

We train a machine learning algorithm to learn cosmological structure formation from N-body simulations. The algorithm infers the relationship between the initial conditions and the final dark matter haloes, without the need to introduce…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-02 Luisa Lucie-Smith , Hiranya V. Peiris , Andrew Pontzen , Michelle Lochner

As hydrodynamic simulations increase in scale and resolution, identifying structures with non-trivial geometries or regions of general interest becomes increasingly challenging. There is a growing need for algorithms that identify a variety…

Instrumentation and Methods for Astrophysics · Physics 2016-02-17 Duncan Forgan , Ian Bonnell , William Lucas , Ken Rice

At early times dark matter has a thermal velocity dispersion of unknown amplitude which, for warm dark matter models, can influence the formation of nonlinear structure on observable scales. We propose a new scheme to simulate cosmologies…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Jens Stücker , Oliver Hahn , Raul E. Angulo , Simon D. M. White

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…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-13 Jiaxin Han , Shaun Cole , Carlos S. Frenk , Alejandro Benitez-Llambay , John Helly

With advances in cosmology and computer science, cosmological simulations now resolve structures in increasingly fine detail. As key tracers of hierarchical structure formation, subhalos are among the most important objects within these…

Instrumentation and Methods for Astrophysics · Physics 2025-12-12 Minxing Li , Yun Wang , Ping He

Over $90$\% of dark matter haloes in cosmological simulations have unresolved properties. This can hinder the dynamical range of simulations and result in systematic biases when modelling cosmological tracers. We aim to more precisely…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-27 Sujatha Ramakrishnan , Violeta Gonzalez-Perez , Gabriele Parimbelli , Gustavo Yepes