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We describe a semi-analytic model to predict the triaxial shapes of dark matter halos utilizing the sequences of random merging events captured in merger trees to follow the evolution of each halo's energy tensor. When coupled with a simple…

Astrophysics of Galaxies · Physics 2026-03-18 Paul Menker , Andrew J. Benson

Weak lensing three-point statistics are powerful probes of the structure of dark matter halos. We propose to use the correlation of the positions of galaxies with the shapes of background galaxy pairs, known as the halo-shear-shear…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-07 Masato Shirasaki , Naoki Yoshida

We focus on the complex relationship between the shape of dark matter halos and the cosmological models underlying their formation. We used three realistic cosmological models from the Dark Energy Universe Simulation suite. They have…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-30 Jean-Michel Alimi , Remy Koskas

A dark matter halo is said to have formed when at least half its mass hass been assembled into a single progenitor. With this definition, it is possible to derive a simple but useful analytic estimate of the distribution of halo formation…

Astrophysics · Physics 2009-09-29 Carlo Giocoli , Jorge Moreno , Ravi K. Sheth , Giuseppe Tormen

The non-spherical shapes of dark matter and gas distributions introduce systematic uncertainties that affect observable-mass relations and selection functions of galaxy groups and clusters. However, the triaxial gas distributions depend on…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-19 Luis Fernando Machado Poletti Valle , Camille Avestruz , David J. Barnes , Arya Farahi , Erwin T. Lau , Daisuke Nagai

We examine the proposal that a model of the large-scale matter distribution consisting of randomly placed haloes with power-law profile, as opposed to a fractal model, can account for the observed power-law galaxy-galaxy correlations. We…

Astrophysics · Physics 2008-11-26 Jose Gaite

We present a non-parametric Lagrangian biasing model and fit the ratio of the halo and mass densities at the field level using the mass-weighted halo field in the AbacusSummit simulations at $z=0.5$. Unlike the perturbative halo bias model…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-09 Xiaohan Wu , Julian B. Munoz , Daniel Eisenstein

We extend the random-walk model of Vitvitska et al. for predicting the spins of dark matter halos from their merger histories. Using updated merger rates, orbital parameter distributions, and N-body constraints we show that this model can…

Astrophysics of Galaxies · Physics 2020-07-08 Andrew Benson , Christoph Behrens , Yu Lu

Aims: We study the dependence of the dynamical properties of dark matter halos on their environment in a whole-sky $\Lambda$CDM light-cone simulation extending to $z\sim 0.65$. The properties of interest are halo shape (parametrized by its…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-27 Maria Chira , Manolis Plionis , Shankar Agarwal

We discuss an analytic approach for modeling structure formation in sheets, filaments and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects which have…

Astrophysics · Physics 2009-07-07 Jiajian Shen , Tom Abel , H. J. Mo , Ravi Sheth

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

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

We present a new, galaxy-halo model of large-scale structure, in which the galaxies entering a given sample are the fundamental objects. Haloes attach to galaxies, in contrast to the standard halo model, in which galaxies attach to haloes.…

Astrophysics · Physics 2009-11-10 Mark C. Neyrinck , Andrew J. S. Hamilton , Nickolay Y. Gnedin

We give an analytical form for the weighted correlation function of peaks in a Gaussian random field. In a cosmological context, this approach strictly describes the formation bias and is the main result here. Nevertheless, we show its…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-24 Licia Verde , Raul Jimenez , Fergus Simpson , Luis Alvarez-Gaume , Alan Heavens , Sabino Matarrese

Tidal gravitational forces can modify the shape of galaxies and clusters of galaxies, thus correlating their orientation with the surrounding matter density field. We study the dependence of this phenomenon, known as intrinsic alignment…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-06 Davide Piras , Benjamin Joachimi , Björn Malte Schäfer , Mario Bonamigo , Stefan Hilbert , Edo van Uitert

Halo Models of large scale structure provide powerful and indispensable tools for phenomenological understanding of the clustering of matter in the Universe. While the halo model builds structures out of the superposition of haloes,…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-26 Alice Chen , Niayesh Afshordi

The dark energy dominated warm dark matter (WDM) model is a promising alternative cosmological scenario. We explore large-scale structure formation in this paradigm. We do this in two different ways: with the halo model approach and with…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Aurel Schneider , Robert E. Smith , Andrea V. Maccio , Ben Moore

The cold dark matter theory predicts triaxial dark matter haloes. The radial distribution of halo ellipticity depends on baryonic processes and the nature of dark matter particles (collisionless or collisional). Here we show that we can use…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Xinzhong Er , Shude Mao , Dandan Xu , Yixian Cao

A model of the gravitationally evolved dark matter distribution, in the Eulerian space, is developed. It is a simple extension of the excursion set model that is commonly used to estimate the mass function of collapsed dark matter haloes.…

Astrophysics · Physics 2009-10-30 Ravi K. Sheth

We investigate the spins and shapes of over a million dark matter haloes identified at z=0 in the Millennium simulation. Our sample spans halo masses ranging from dwarf galaxies to rich galaxy clusters. The very large dynamic range of this…

Astrophysics · Physics 2008-11-26 Philip Bett , Vincent Eke , Carlos S. Frenk , Adrian Jenkins , John Helly , Julio Navarro