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The properties of the matter density field in the initial conditions have a decisive impact on the features of the large-scale structure of the Universe as observed today. These need to be studied via $N$-body simulations, which are…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-21 Jazhiel Chacón , Isidro Gómez-Vargas , Ricardo Menchaca Méndez , José Alberto Vázquez

The simplest models of dark matter halo formation are based on the heuristic assumption, motivated by spherical collapse, that virialized haloes originate from initial regions that are maxima of the smoothed density field. Here, we replace…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-28 Marcello Musso , Ravi K. Sheth

It has normally been assumed that primordial black holes (PBHs) always form with mass approximately equal to the mass contained within the horizon at that time. Recent work studying the application of critical phenomena in gravitational…

Astrophysics · Physics 2016-08-25 Anne M Green , Andrew R Liddle

The excursion set approach is a framework for estimating how the number density of nonlinear structures in the cosmic web depends on the expansion history of the universe and the nature of gravity. A key part of the approach is the…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-31 Farnik Nikakhtar , Mohammadreza Ayromlou , Shant Baghram , Sohrab Rahvar , M. Reza Rahimi Tabar , Ravi K. Sheth

We use an array of high-resolution N-body simulations to determine the mass function of dark matter haloes at redshifts 10-30. We develop a new method for compensating for the effects of finite simulation volume that allows us to find an…

Astrophysics · Physics 2008-11-26 Darren Reed , Richard Bower , Carlos Frenk , Adrian Jenkins , Tom Theuns

We present measurements of the number density of voids in the dark matter distribution from a series of N-body simulations of a \Lambda CDM cosmology. We define voids as spherical regions of \rho_v = 0.2\rho_m around density minima in order…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-28 Elise Jennings , Yin Li , Wayne Hu

N-body simulations have demonstrated a correlation between the properties of haloes and their environment. In this paper, we assess whether the ellipsoidal collapse model can produce a similar dependence. First, we explore the statistical…

Astrophysics · Physics 2009-11-13 Vincent Desjacques

Accurate modelling of the one-to-two halo transition has long been difficult to achieve. We demonstrate that physically motivated halo definitions that respect the bimodal phase-space distribution of dark matter particles near halos…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-11 Edgar M. Salazar , Eduardo Rozo , Rafael García , Nickolas Kokron , Susmita Adhikari , Benedikt Diemer , Calvin Osinga

We build a simple analytical model for the bias of dark matter halos that applies to objects defined by an arbitrary density threshold, $200\leq\deltas\leq 1600$, and that provides accurate predictions from low-mass to high-mass halos. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Patrick Valageas

The clustering of galaxies in ongoing and upcoming galaxy surveys contains a wealth of cosmological information, but extracting this information is a non-trivial task since galaxies and their host haloes are stochastic tracers of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-30 Tobias Baldauf , Uroš Seljak , Robert E. Smith , Nico Hamaus , Vincent Desjacques

We examine the linear density contrast at collapse time, $\delta_c$ for large-scale structure in dynamical dark energy cosmologies, including models with early dark energy. Contrary to previous results, we find that as long as dark energy…

Astrophysics · Physics 2010-03-19 Matthew J. Francis , Geraint F. Lewis , Eric V. Linder

A parameterized model of the mass distribution within the Milky Way is fitted to the available observational constraints. The most important single parameter is the ratio of the scale length R_d* of the stellar disk to R0. The disk and…

Astrophysics · Physics 2020-11-25 Walter Dehnen , James Binney

In the framework of the stochastic theory for hierarchical clustering, we investigate the time-dependent solutions of the Fokker-Planck equation describing the statistics of dark matter halos, and discuss the typical timescales needed for…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-14 A. Lapi , T. Ronconi , L. Danese

We revisit the study of the mass functions and the bias of dark matter halos. Focusing on the limit of rare massive halos, we point out that exact analytical results can be obtained for the large-mass tail of the halo mass function. This is…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-22 P. Valageas

It is well established from cosmological simulations that dark matter haloes are not precisely self-similar and an additional parameter, beyond their concentration, is required to accurately describe their spherically-averaged mass density…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-08 Shaun T. Brown , Ian G. McCarthy , Sam G. Stafford , Andreea S. Font

$N$-body cosmological simulations are an essential tool to understand the observed distribution of galaxies. We use the MultiDark simulation suite, run with the Planck cosmological parameters, to revisit the mass and velocity functions. At…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-16 Johan Comparat , Francisco Prada , Gustavo Yepes , Anatoly Klypin

In the CDM paradigm, the halo mass function is a sensitive probe of the cosmic structure. In observations, halo mass is typically estimated from its relation with other observables. The resulting halo mass function is subject to systematic…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-09 Fuyu Dong , Jun Zhang , Xiaohu Yang , Jiajun Zhang , Wentao Luo

The smallest dark matter haloes are the first objects to form in the hierarchical structure formation of cold dark matter (CDM) cosmology and are expected to be the densest and most fundamental building blocks of CDM structures in our…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-06 Chiamaka Okoli , Niayesh Afshordi

Among the most fundamental properties of a dark matter halo is its density profile. Motivated by the recent proposal by Garc\'ia et al. [R. Garc\'ia et. al., MNRAS 521, 2464 (2023)] to define a dynamical halo as the collection of orbiting…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-02 Tristen Shields , Edgar M. Salazar , Eduardo Rozo , Aakanksha Adya , Calvin Osinga , Ze'ev Vladimir

We study the evolution of the halo-halo correlation function and bias in a LCDM model using very high-resolution N-body simulations. The high force and mass resolution allows dark matter (DM) halos to survive in the tidal fields in…

Astrophysics · Physics 2007-05-23 Andrey Kravtsov , Anatoly Klypin , Pedro Colin , Alexei Khokhlov