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We introduce a simple model for the formation of voids. In this model the underdensity of galaxies in voids is the product of two factors. The first arises from a gravitational expansion of the negative density perturbation. The second is…

Astrophysics · Physics 2009-10-31 Yasmin Friedmann , Tsvi Piran

Modern deep learning usually treats models as separate artifacts: trained independently, specialized for particular purposes, and replaced when improved versions appear. This thesis studies model merging as an alternative paradigm:…

Machine Learning · Computer Science 2026-05-05 Donato Crisostomi

The origins and mergers of supermassive black holes (BHs) remain a mystery. We describe a scenario from a novel multi-physics simulation featuring rapid ($\lesssim 1\,$Myr) hyper-Eddington gas capture by a $\sim 1000\,{\rm M}_{\odot}$…

Astrophysics of Galaxies · Physics 2024-07-09 Yanlong Shi , Kyle Kremer , Philip F. Hopkins

We present a statistical analysis of flybys of dark matter halos compared to mergers using cosmological $N$-body simulations. We mainly focus on gravitationally interacting target halos with mass of $10^{10.8}-10^{13.0}h^{-1}M_{\odot}$, and…

Astrophysics of Galaxies · Physics 2019-12-18 Sung-Ho An , Juhan Kim , Jun-Sung Moon , Suk-Jin Yoon

Recent observational and theoretical studies have suggested that supermassive black holes (SMBHs) grow mostly through non-merger (`secular') processes. Since galaxy mergers lead to dynamical bulge growth, the only way to observationally…

The expanding complex pattern of filaments, walls and voids build the evolving cosmic web with material flowing from underdense onto high density regions. Here we explore the dynamical behaviour of voids and galaxies in void shells relative…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-19 Marcelo Lares , Haliana Luparello , Victoria Maldonado , Andrés N. Ruiz , Dante J. Paz , Laura Cecarelli , Diego Garcia Lambas

Despite a history that dates back at least a quarter of a century studies of voids in the large--scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void--finding algorithms, a…

We present an analysis of the small-to-intermediate scale clustering of samples of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey and the 2dF-SDSS LRG and QSO (2SLAQ) survey carefully matched to have the same rest-frame…

We study the evolution of the cross-correlation between voids and the mass density field - i.e. of void profiles. We show that approaches based on the spherical model alone miss an important contribution to the evolution on large scales of…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-09 Elena Massara , Ravi K. Sheth

The evolution of dense star clusters is followed by direct high-accuracy N-body simulation. The problem is to first order a gravitational N-body problem, but stars evolve due to astrophysics and the more massive ones form black holes or…

Hierarchical black hole (BH) mergers are one of the most straightforward mechanisms to produce BHs inside and above the pair-instability mass gap. Here, we investigate the impact of globular cluster (GC) evolution on hierarchical mergers,…

High Energy Astrophysical Phenomena · Physics 2024-08-14 Stefano Torniamenti , Michela Mapelli , Carole Périgois , Manuel Arca Sedda , M. Celeste Artale , Marco Dall'Amico , M. Paola Vaccaro

We present a new algorithm for generating merger trees and halo catalogs which explicitly ensures consistency of halo properties (mass, position, and velocity) across timesteps. Our algorithm has demonstrated the ability to improve both the…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-15 Peter S. Behroozi , Risa H. Wechsler , Hao-Yi Wu , Michael T. Busha , Anatoly A. Klypin , Joel R. Primack

Observations suggest that red central galaxies align closely with their group galaxies and the large-scale environment.This finding was also replicated in simulations, which added information about the alignment of the stars that form the…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-31 Facundo Rodriguez , Manuel Merchán , M. Celeste Artale

Cosmic voids provide a unique environment to study galaxy formation and evolution. In this paper, we analyse a set of hydrodynamic zoom-in simulations of voids, to analyse in detail their inner structures. These voids were identified in a…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-16 Agustín M. Rodríguez Medrano , Dante J. Paz , Federico A. Stasyszyn , Andrés N. Ruiz

We use the Aquarius simulation series to study the imprint of assembly history on the structure of Galaxy-mass cold dark matter halos. Our results confirm earlier work regarding the influence of mergers on the mass density profile and the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Jie Wang , J. F. Navarro , C. S. Frenk , S. D. M. White , V. Springel , A. Jenkins , A. Helmi , A. Ludlow , M. Vogelsberger

In $\Lambda$CDM cosmology, galaxies form and evolve in their host dark matter (DM) halos. Halo mass is crucial for understanding the halo-galaxy connection. The abundance matching (AM) technique has been widely used to derive the halo…

The abundance of the most massive objects in the Universe at different epochs is a very sensitive probe of the cosmic background evolution and of the growth history of density perturbations, and could provide a powerful tool to distinguish…

Cosmology and Nongalactic Astrophysics · Physics 2012-02-22 Marco Baldi

We present a simple, empirically motivated model that simultaneously predicts the evolution of the mean size and the comoving mass density of massive early-type galaxies from z=2 to the present. First we demonstrate that some size evolution…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 Arjen van der Wel , Eric F. Bell , Frank C. van den Bosch , Anna Gallazzi , Hans-Walter Rix

The observational data of high redshift galaxies become increasingly abundant, especially since the operation of the James Webb Space Telescope (JWST), which allows us to verify and optimize the galaxy formation model at high redshifts. In…

Astrophysics of Galaxies · Physics 2023-12-11 Kemeng Li , Zhen Jiang , Ping He , Qi Guo , Jie Wang

We study statistical properties of voids in the distribution of mass, dark-matter haloes and galaxies (B_J<-16) in a LCDM numerical simulation populated with galaxies using a semi-analytic galaxy formation model(GALFORM, Cole et al. 2000).…

Astrophysics · Physics 2009-11-13 N. D. Padilla , L. Ceccarelli , D. G. Lambas
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