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Random forest (RF) stands out as a highly favored machine learning approach for classification problems. The effectiveness of RF hinges on two key factors: the accuracy of individual trees and the diversity among them. In this study, we…

Machine Learning · Computer Science 2024-10-28 Ye-eun Kim , Seoung Yun Kim , Hyunjoong Kim

The relative roles of mergers and star formation in regulating galaxy growth are still a matter of intense debate. We here present our DECODE, a new Discrete statistical sEmi-empiriCal mODEl specifically designed to predict rapidly and…

We conducted an analysis on dark matter halo properties following major and minor mergers to advance our understanding of halo evolution. In this work, we analyzed ~80,000 dark matter halos from the Bolshoi-Planck cosmological simulation…

Astrophysics of Galaxies · Physics 2017-11-28 Peter Wu , Shawn Zhang

In this paper, we propose Hierarchical Federated Learning with Momentum Acceleration (HierMo), a three-tier worker-edge-cloud federated learning algorithm that applies momentum for training acceleration. Momentum is calculated and…

Machine Learning · Computer Science 2022-10-27 Zhengjie Yang , Sen Fu , Wei Bao , Dong Yuan , Albert Y. Zomaya

Extended stellar haloes are a natural by-product of the hierarchical formation of massive galaxies. If merging is a non-negligible factor in the growth of our Galaxy, evidence of such events should be encoded in its stellar halo. Reliable…

Astrophysics of Galaxies · Physics 2018-12-26 Jovan Veljanoski , Amina Helmi , Maarten Breddels , Lorenzo Posti

The merging rate of cosmic structures is computed, relying on the Ansatz that they can be predicted in the initial linear density field from the coalescence of critical points with increasing smoothing scale, used here as a proxy for cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-28 Corentin Cadiou , Christophe Pichon , Sandrine Codis , Marcello Musso , Dmitri Pogosyan , Yohan Dubois , Jean-François Cardoso , Simon Prunet

Phylogenetic tree reconciliation is employed for the examination of coevolution between host and symbiont species. An important concern is the requirement for dependable cost values when selecting event-based parsimonious reconciliation.…

Quantitative Methods · Quantitative Biology 2023-08-30 Blerina Sinaimeri , Laura Urbini , Marie-France Sagot , Catherine Matias

Virtually any investigation involving dark matter halos relies on a definition of their radius, mass, and of whether they are a subhalo. The halo boundary is most commonly defined to include a spherical overdensity contrast (such as R200c,…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-25 Benedikt Diemer

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

We investigate various phenomenological schemes for the rapid generation of 3D mock galaxy catalogues with a given power spectrum and bispectrum. We apply the fast bispectrum estimator \MODALLSS{} to these mock galaxy catalogues and compare…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-10 Johnathan Hung , Marc Manera , E. P. S. Shellard

Applications in many domains are based on a series of traversals of tree structures, and fusing these traversals together to reduce the total number of passes over the tree is a common, important optimization technique. In applications such…

Programming Languages · Computer Science 2019-04-22 Laith Sakka , Kirshanthan Sundararajah , Ryan R. Newton , Milind Kulkarni

In this study, we perform a halo-finder code comparison between Rockstar and CompaSO. Based on our previous analysis aiming at quantifying resolution of $N$-body simulations by exploiting large (up to $N=4096^3$) simulations of scale-free…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-07 Sara Maleubre , Daniel J. Eisenstein , Lehman H. Garrison , Michael Joyce

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

Elucidating the connection between the properties of galaxies and the properties of their hosting haloes is a key element in galaxy formation. When the spatial distribution of objects is also taken under consideration, it becomes very…

Predicting the merger timescale ($\tau_{\rm merge}$) of merging dark matter halos, based on their orbital parameters and the structural properties of their hosts, is a fundamental problem in gravitational dynamics that has important…

Astrophysics of Galaxies · Physics 2020-10-28 Rhys J. J. Poulton , Chris Power , Aaron S. G. Robotham , Pascal J. Elahi , Claudia del P. Lagos

Observational studies show that voids are prominent features of the large scale structure of the present day Universe. Even though their emerging from the primordial density perturbations and evolutionary patterns differ from dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-23 Esra Russell

We examine the reliability of the merger trees generated for the Monte-Carlo modeling of galaxy formation. In particular we focus on the cold gas fraction predicted from the merger trees with different assumptions on the progenitor…

Astrophysics · Physics 2015-06-24 Mamoru Shimizu , Tetsu Kitayama , Shin Sasaki , Yasushi Suto

This paper investigates the execution of tree-shaped task graphs using multiple processors. Each edge of such a tree represents some large data. A task can only be executed if all input and output data fit into memory, and a data can only…

Distributed, Parallel, and Cluster Computing · Computer Science 2014-10-02 Lionel Eyraud-Dubois , Loris Marchal , Oliver Sinnen , Frédéric Vivien

Filtered graphs provide a powerful tool for data clustering. The triangular maximally filtered graph (TMFG) method, when combined with the directed bubble hierarchy tree (DBHT) method, defines a useful algorithm for hierarchical data…

Distributed, Parallel, and Cluster Computing · Computer Science 2024-08-20 Steven Raphael , Julian Shun

We use the "Millennium Simulation" to study the mass function of accreted sub-halos during merger events in the dark halo assembly history. Our study includes three kinds of sub-halo mergers: (1) mergers that happen to the main progenitor…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-04 Yun Li , Houjun Mo