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Related papers: MEGA: Merger graphs of structure formation

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Merger trees track the hierarchical assembly of dark matter halos across cosmic time and serve as essential inputs for semi-analytic models of galaxy formation. However, conventional methods for constructing merger trees rely on ad-hoc…

Astrophysics of Galaxies · Physics 2025-10-02 Tri Nguyen , Chirag Modi , Siddharth Mishra-Sharma , L. Y. Aaron Yung , Rachel S. Somerville

We examine the effect of using different halo finders and merger tree building algorithms on galaxy properties predicted using the GALFORM semi-analytical model run on a high resolution, large volume dark matter simulation. The halo…

Galaxies with Milky Way-like stellar masses have a wide range of bulge and black hole masses; in turn, these correlate with other properties such as star formation history. While many processes may drive bulge formation, major and minor…

Galaxies are thought to reside inside of large gravitationally bound structures of dark matter, so-called haloes. While the smallest of these haloes host no or only a few stars, the biggest host entire clusters of galaxies. Over cosmic…

Instrumentation and Methods for Astrophysics · Physics 2022-09-16 Mattis Magg , Tilman Hartwig , Li-Hsin Chen , Yuta Tarumi

We evaluate the accuracy of semi-analytic merger-trees by comparing them with the merging histories of dark-matter halos in N-body simulations, focusing on the joint distribution of the number of progenitors and their masses. We first…

Astrophysics · Physics 2009-10-30 Rachel S. Somerville , Gerard Lemson , Tsafrir S. Kolatt , Avishai Dekel

We construct merger trees from the largest database of dark matter haloes to date provided by the Millennium simulation to quantify the merger rates of haloes over a broad range of descendant halo mass (1e12 < M0 < 1e15 Msun), progenitor…

Astrophysics · Physics 2009-11-13 Onsi Fakhouri , Chung-Pei Ma

We model the formation and evolution of galaxy clusters in the framework of an extended dark matter halo merger-tree algorithm that includes baryons and incorporates basic physical considerations. Our modified treatment is employed to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Irina Dvorkin , Yoel Rephaeli

The cosmic web plays a major role in the formation and evolution of galaxies and defines, to a large extent, their properties. However, the relation between galaxies and environment is still not well understood. Here we present a machine…

Astrophysics of Galaxies · Physics 2018-04-11 Jianan Hui , Miguel A. Aragon-Calvo , Xinping Cui , James M. Flegal

Merger trees track the evolution of halos across multiple snapshots. They assign for halos of a particular snapshot, the set of halos from previous snapshots they possibly originated from. In this work, Association rule analysis a well…

Instrumentation and Methods for Astrophysics · Physics 2017-01-18 B. Hareesh Gautham , Rahul Nigam

We introduce and apply a new approach to probe the response of galactic stellar haloes to the interplay between cosmological merger histories and galaxy formation physics. We perform dark matter-only, zoomed simulations of two Milky…

Astrophysics of Galaxies · Physics 2022-01-21 Martin P. Rey , Tjitske K. Starkenburg

Cosmological N-body simulations rank among the most computationally intensive efforts today. A key challenge is the analysis of structure, substructure, and the merger history for many billions of compact particle clusters, called halos.…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-20 Esteban Rangel , Nicholas Frontiere , Salman Habib , Katrin Heitmann , Wei-keng Liao , Ankit Agrawal , Alok Choudhary

In a previous paper, we described a new method for including detailed information about substructure in semi-analytic models of dark matter halo formation based on merger trees. In this paper, we present the basic predictions of our full…

Astrophysics · Physics 2009-11-10 James E. Taylor , Arif Babul

We developed a new method to extract halo merger rates from the Millennium Simulation. First, by removing superfluous mergers that are artifacts of the FOF halo finder, we find a lower merger rate compared to previous work. The reductions…

Astrophysics · Physics 2010-11-02 S. Genel , R. Genzel , N. Bouché , T. Naab , A. Sternberg

We present an algorithm for generating merger histories of dark matter haloes. The algorithm is based on the excursion set approach with moving barriers whose shape is motivated by the ellipsoidal collapse model of halo formation. In…

Astrophysics · Physics 2009-01-03 Jorge Moreno , Carlo Giocoli , Ravi K. Sheth

According to the hierarchical model, small galaxies form first and merge together to form bigger objects. In parallel, galaxies assemble their mass through accretion from cosmic filaments. Recently, the increased spatial resolution of the…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-30 Benjamin L'Huillier , Francoise Combes , Benoit Semelin

A simple, 1-equation, galaxy formation model is applied to both the halo merger tree derived from a high-resolution dissipationless cosmological simulation and to 1/4 million Monte-Carlo halo merger trees. The galaxy formation model…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Gary A. Mamon , Dylan Tweed , Trinh X. Thuan , Andrea Cattaneo

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

We use semi-analytic models and cosmological merger trees to provide the initial conditions for multi-merger numerical hydrodynamic simulations, and exploit these simulations to explore the effect of galaxy interaction and merging on star…

Astrophysics of Galaxies · Physics 2015-08-06 Wouter Karman , Andrea V. Maccio , Rahul Kannan , Benjamin P. Moster , Rachel S. Somerville

We present TreeFrog, a massively parallel halo merger tree builder that is capable comparing different halo catalogues and producing halo merger trees. The code is written in c++11, use the MPI and OpenMP API's for parallelisation, and…

Instrumentation and Methods for Astrophysics · Physics 2019-08-15 Pascal J. Elahi , Rhys J. J. Poulton , Rodrigo J. Tobar , Rodrigo Canas , Claudia del P. Lagos , Chris Power , Aaron S. G. Robotham

One of the generic predictions of modern cosmological models is that large galaxies should have experienced many mergers with smaller galaxies at some point in their past. Debris from such encounters will leave spatially distinct…

Astrophysics · Physics 2007-05-23 James E. Taylor