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Galaxies co-evolve with their host dark matter halos. Models of the galaxy-halo connection, calibrated using cosmological hydrodynamic simulations, can be used to populate dark matter halo catalogs with galaxies. We present a new method for…

Instrumentation and Methods for Astrophysics · Physics 2023-06-22 John F. Wu , Christian Kragh Jespersen

Current simulation of metal forging processes use advanced finite element methods. Such methods consist of solving mathematical equations, which takes a significant amount of time for the simulation to complete. Computational time can be…

Numerical Analysis · Mathematics 2023-03-20 Meduri Venkata Shivaditya , José Alves , Francesca Bugiotti , Frederic Magoules

A key yet unresolved question in modern-day astronomy is how galaxies formed and evolved under the paradigm of the $\Lambda$CDM model. A critical limiting factor lies in the lack of robust tools to describe the merger history through a…

Astrophysics of Galaxies · Physics 2022-07-07 Kwok Sun Tang , Yuan-Sen Ting

We investigate the evolution of the galaxy merger rate predicted by two semi-analytical galaxy formation models implemented on the Millennium Simulation of dark matter structure growth. The fraction of merging galaxy pairs at each time-step…

Astrophysics · Physics 2008-02-21 Abilio Mateus

Several semi-analytic models (SAMs) try to explain how galaxies form, evolve and interact inside the dark matter large-scale structure. These SAMs can be tested by comparing their predictions for galaxy-galaxy-galaxy-lensing (G3L), which is…

In order to prepare for the upcoming wide-field cosmological surveys, large simulations of the Universe with realistic galaxy populations are required. In particular, the tendency of galaxies to naturally align towards overdensities, an…

Identifying merging galaxies is an important - but difficult - step in galaxy evolution studies. We present random forest classifications of galaxy mergers from simulated JWST images based on various standard morphological parameters. We…

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

A simple, fully connected neural network with a single hidden layer is used to estimate stellar masses for star-forming galaxies. The model is trained on broad-band photometry - from far-ultraviolet to mid-infrared wavelengths - generated…

Instrumentation and Methods for Astrophysics · Physics 2025-07-15 E. Elson

We present the first results from applying the Santa Cruz semi-analytic model (SAM) for galaxy formation on merger trees extracted from a dark matter only version of the IllustrisTNG (TNG) simulations. We carry out a statistical comparison…

We investigate the evolution of dwarf galaxies using N -body/SPH simulations that incorporate their formation histories through merger trees constructed using the ex- tended Press-Schechter formalism. The simulations are computationally…

Astrophysics of Galaxies · Physics 2015-06-19 Annelies Cloet-Osselaer , Sven De Rijcke , Bert Vandenbroucke , Joeri Schroyen , Mina Koleva , Robbert Verbeke

We define a general class of network formation models, Statistical Exponential Random Graph Models (SERGMs), that nest standard exponential random graph models (ERGMs) as a special case. We provide the first general results on when these…

Physics and Society · Physics 2014-06-26 Arun G. Chandrasekhar , Matthew O. Jackson

Graph Neural Networks (GNNs) have attracted increasing attention in recent years and have achieved excellent performance in semi-supervised node classification tasks. The success of most GNNs relies on one fundamental assumption, i.e., the…

Machine Learning · Computer Science 2024-12-03 Junchao Lin , Yuan Wan , Jingwen Xu , Xingchen Qi

Semi-analytic models (SAMs) have been treating galaxy populations as dynamical systems for $\gtrsim50$ years, but their evolution equations remain poorly constrained. We introduce sapphire, a modular, automatically differentiable,…

We present a novel methodology to improve predictions of galaxy formation histories by incorporating semi-stochastic corrections to account for short-timescale variability. Our paper addresses limitations in existing models that capture…

Astrophysics of Galaxies · Physics 2025-07-24 Jayashree Behera , Rita Tojeiro , Harry George Chittenden

We use stripped-down versions of three semi-analytic galaxy formation models to study the influence of different assumptions about gas cooling and galaxy mergers. By running the three models on identical sets of merger trees extracted from…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-07 Gabriella De Lucia , Michael Boylan-Kolchin , Andrew J. Benson , Fabio Fontanot , Pierluigi Monaco

We develop a new class of random graph models for the statistical estimation of network formation -- subgraph generated models (SUGMs). Various subgraphs -- e.g., links, triangles, cliques, stars -- are generated and their union results in…

Physics and Society · Physics 2024-11-27 Arun G. Chandrasekhar , Matthew O. Jackson

Maps of cosmic structure produced by galaxy surveys are one of the key tools for answering fundamental questions about the Universe. Accurate theoretical predictions for these quantities are needed to maximize the scientific return of these…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-02 Noah Kasmanoff , Francisco Villaescusa-Navarro , Jeremy Tinker , Shirley Ho

This paper describes a new publicly available codebase for modelling galaxy formation in a cosmological context, the "Semi-Analytic Galaxy Evolution" model, or SAGE for short. SAGE is a significant update to that used in Croton et al.…

Modifications of the equations of general relativity at large distances offer one possibility to explain the observed properties of our Universe without invoking a cosmological constant. Numerous proposals for such modified gravity…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Fabio Fontanot , Ewald Puchwein , Volker Springel , Davide Bianchi