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Linking the properties of galaxies to the assembly history of their dark matter haloes is a central aim of galaxy evolution theory. This paper introduces a dimensionless parameter $s\in[0,1]$, the "tree entropy", to parametrise the geometry…

Astrophysics of Galaxies · Physics 2020-02-14 Danail Obreschkow , Pascal J. Elahi , Claudia del P. Lagos , Rhys J. J. Poulton , Aaron D. Ludlow

Feature level sets (FLS) have shown significant potential in the analysis of multi-field data by using traits defined in attribute space to specify features in the domain. In this work, we address key challenges in the practical use of FLS:…

Machine Learning · Computer Science 2025-01-14 Danhua Lei , Jochen Jankowai , Petar Hristov , Hamish Carr , Leif Denby , Talha Bin Masood , Ingrid Hotz

We introduce the contour process to describe the geometrical properties of merger trees. The contour process produces a one-dimensional object, the contour walk, which is a translation of the merger tree. We portray the contour walk through…

Astrophysics · Physics 2015-05-13 Jaime E. Forero-Romero

The merger and accretion probabilities of dark matter halos have so far only been calculated for an infinitesimal time interval. This means that a Monte-Carlo simulation with very small time steps is necessary to find the merger history of…

Astrophysics · Physics 2008-10-15 Esfandiar Alizadeh , Benjamin Wandelt

Galaxy formation and evolution models, such as semi-analytic models, are powerful theoretical tools for predicting how galaxies evolve across cosmic time. These models follow the evolution of galaxies based on the halo assembly histories…

A key ingredient for semi-analytic models (SAMs) of galaxy formation is the mass assembly history of haloes, encoded in a tree structure. The most commonly used method to construct halo merger histories is based on the outcomes of…

Astrophysics of Galaxies · Physics 2022-06-28 Sandra Robles , Jonathan S. Gómez , Adín Ramírez Rivera , Nelson D. Padilla , Diego Dujovne

Merge trees are a type of topological descriptors that record the connectivity among the sublevel sets of scalar fields. They are among the most widely used topological tools in visualization. In this paper, we are interested in sketching a…

Computational Geometry · Computer Science 2021-06-01 Mingzhe Li , Sourabh Palande , Lin Yan , Bei Wang

In this work, we propose trait-based merge trees a generalization of merge trees to feature level sets, targeting the analysis of tensor field or general multi-variate data. For this, we employ the notion of traits defined in attribute…

Machine Learning · Computer Science 2023-08-21 Jochen Jankowai , Talha Bin Masood , Ingrid Hotz

Merge trees, a type of topological descriptor, serve to identify and summarize the topological characteristics associated with scalar fields. They present a great potential for the analysis and visualization of time-varying data. First,…

Human-Computer Interaction · Computer Science 2021-08-02 Lin Yan , Talha Bin Masood , Farhan Rasheed , Ingrid Hotz , Bei Wang

We construct merger trees of dark matter haloes and quantify their merger rates and mass growth rates using the joint dataset from the Millennium and Millennium-II simulations. The finer resolution of the Millennium-II Simulation has…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-26 Onsi Fakhouri , Chung-Pei Ma , Michael Boylan-Kolchin

We argue that a universal density profile for dark matter halos arises as a natural consequence of hierarchical structure formation. It is a fixed point in the process of repeated mergers. We present analytic and numerical arguments for the…

Astrophysics · Physics 2008-02-03 D. Syer , Simon D. M. White

(abridged) We study the mass assembly history (MAH) of dark matter haloes. We compare MAHs obtained using (i) merger trees constructed with the extended Press-Schechter (EPS) formalism, (ii) numerical simulations, and (iii) the Lagrangian…

Astrophysics · Physics 2008-11-26 Yun Li , H. J. Mo , Frank C. van den Bosch , W. P. Lin

We derive analytic merger rates for dark-matter haloes within the framework of the Extended Press-Schechter (EPS) formalism. These rates become self-consistent within EPS once we realize that the typical merger in the limit of a small…

Astrophysics · Physics 2009-11-13 Eyal Neistein , Avishai Dekel

We study the ability of PINOCCHIO (PINpointing Orbit-Crossing Collapsed HIerarchical Objects) to predict the merging histories of dark matter (DM) haloes, comparing the PINOCCHIO predictions with the results of two large N-body simulations…

Astrophysics · Physics 2009-11-07 G. Taffoni , P. Monaco , T. Theuns

Dark matter halo merger trees are now routinely extracted from cosmological simulations of structure formation. These trees are frequently used as inputs to semi-analytic models of galaxy formation to provide the backbone within which…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Andrew J. Benson , Stefano Borgani , Gabriella De Lucia , Michael Boylan-Kolchin , Pierluigi Monaco

We develop a simple model for estimating the mass growth histories of dark matter halos. The model is based on a fit to the formation time distribution, where formation is defined as the earliest time that the main branch of the merger tree…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Carlo Giocoli , Giuseppe Tormen , Ravi K. Sheth

Hash codes are a very efficient data representation needed to be able to cope with the ever growing amounts of data. We introduce a random forest semantic hashing scheme with information-theoretic code aggregation, showing for the first…

Computer Vision and Pattern Recognition · Computer Science 2015-04-20 Qiang Qiu , Guillermo Sapiro , Alex Bronstein

We construct merger trees based on the extended Press-Schechter theory (EPS) in order to study the merger rates of dark matter haloes over a range of present day mass ($10^{10}M_{\sun}\leq M_0 \leq10^{15}M_{\sun}$), progenitor mass…

Cosmology and Nongalactic Astrophysics · Physics 2009-05-07 Nicos Hiotelis

Merging haloes with similar masses (i.e., major mergers) pose significant challenges for halo finders. We compare five halo finding algorithms' (AHF, HBT, Rockstar, SubFind, and VELOCIraptor) recovery of halo properties for both isolated…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-28 Peter Behroozi , Alexander Knebe , Frazer R. Pearce , Pascal Elahi , Jiaxin Han , Hanni Lux , Yao-Yuan Mao , Stuart I. Muldrew , Doug Potter , Chaichalit Srisawat

The implementation of ACACIA, a new algorithm to generate dark matter halo merger trees with the Adaptive Mesh Refinement (AMR) code RAMSES, is presented. The algorithm is fully parallel and based on the Message Passing Interface (MPI). As…

Astrophysics of Galaxies · Physics 2021-11-25 Mladen Ivkovic , Romain Teyssier