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Violent relaxation during the collapse of a galaxy halo is known to be incomplete in realistic cases such as cosmological infall or mergers. We adopt a physical picture of strong but short lived interactions between potential fluctuations…

Astrophysics · Physics 2009-10-31 A. Mangalam , R. Nityananda , S. Sridhar

Halo Abundance Matching has been used to construct a one-parameter mapping between galaxies and dark matter haloes by assuming that halo mass and galaxy luminosity (or stellar mass) are monotonically related. While this approach has been…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-19 Andrea Kulier , Jeremiah P. Ostriker

According to the now strongly supported concordance $\Lambda$CDM model, galaxies may be grossly described as a luminous component embedded in a dark matter halo. The density profile of these mass dominating haloes may be determined by N -…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-04 A. Del Popolo , V. F. Cardone

Primordial black holes (PBHs) can form from gravitational collapse of large overdensities in the early Universe, giving rise to rich phenomena in astrophysics and cosmology. We develop a novel, general, and systematic method based on theory…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-09 Shi Pi , Misao Sasaki , Volodymyr Takhistov , Jianing Wang

The patch like model of the hierarchical galaxy formation in the $\Lambda$CDM cosmological model with small damping scale is considered. In this model galaxies and clusters of galaxies are identified with rare high density peaks, what…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-02 M. Demiański , A. Doroshkevich

The abundance of massive dark matter halos hosting galaxy clusters provides an important test of the masses of relic neutrino species. The dominant effect of neutrino mass is to lower the typical amplitude of density perturbations that…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-03 Marilena LoVerde

In this letter, combining peak theory and the numerical analysis of gravitational collapse in the radiation dominated era, we show that the abundance of primordial blacks holes, generated by an enhancement in the inflationary power…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-16 Cristiano Germani , Ilia Musco

We exploit the excursion set approach in integral formulation to derive novel, accurate analytic approximations of the unconditional and conditional first crossing distributions, for random walks with uncorrelated steps and general shapes…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 A. Lapi , P. Salucci , L. Danese

In a previous paper, we described a new method for including detailed information about substructure in semi-analytic models of halo formation based on merger trees. In this paper, we compare the predictions of our model with results from…

Astrophysics · Physics 2009-11-10 James E. Taylor , Arif Babul

We train a machine learning algorithm to learn cosmological structure formation from N-body simulations. The algorithm infers the relationship between the initial conditions and the final dark matter haloes, without the need to introduce…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-02 Luisa Lucie-Smith , Hiranya V. Peiris , Andrew Pontzen , Michelle Lochner

We study the formation of the Milky Way's halo in a $\Lambda$CDM cosmology by scaling down a high resolution simulation of the formation of a cluster of galaxies. We determine how much phase-space substructure is left over from the objects…

Astrophysics · Physics 2009-09-25 Amina Helmi , Simon D. M. White , Volker Springel

Dark matter (DM) haloes forming near the thermal cut-off scale of the density perturbations are unique, since they are the smallest objects and form through monolithic gravitational collapse, while larger haloes contrastingly have…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-06 Go Ogiya , Oliver Hahn

Mock halo catalogues are indispensable data products for developing and validating cosmological inference pipelines. A major challenge in generating mock catalogues is modelling the halo or galaxy bias, which is the mapping from matter…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-16 Simon Ding , Guilhem Lavaux , Jens Jasche

Galaxies can form in a sufficiently deep gravitational potential so that efficient gas cooling occurs. We estimate that such potential is provided by a halo of mass $M \gtsim M_{c} \approx 7.0 \times 10^{12} ~ (\Delta_{c}(z)…

Astrophysics · Physics 2009-09-07 Hung-Yu Jian , Chia-Hung Chien , Tzihong Chiueh

We obtain predictions for the properties of cold dark matter annihilation radiation using high resolution hydrodynamic zoom-in cosmological simulations of Milky Way-like galaxies (APOSTLE project) carried out as part of the "Evolution and…

Dark-matter halos are the scaffolding around which galaxies and clusters are built. They form when the gravitational instability of primordial density fluctuations causes regions which are denser than average to slow their cosmic expansion,…

Astrophysics · Physics 2007-05-23 Ilian T. Iliev , Paul R. Shapiro

In this work we investigate the spherical collapse model in flat FRW dark energy universes. We consider the Holographic Dark Energy (HDE) model as a dynamical dark energy scenario with a slowly time-varying equation-of-state (EoS) parameter…

General Relativity and Quantum Cosmology · Physics 2015-01-27 Tayebe Naderi , Mohammad Malekjani , Francesco Pace

Adaptive SPH and N-body simulations were carried out to study the collapse and evolution of dark matter halos that result from the gravitational instability and fragmentation of cosmological pancakes. Such halos resemble those formed by…

Astrophysics · Physics 2007-05-23 Marcelo A. Alvarez , Paul R. Shapiro , Hugo Martel

The study by White (1984) on the growth of angular momentum in dark haloes is extended towards a more detailed investigation of the spin parameter $\lambda\equiv L\sqrt{E}/{G M^{2.5}}$. Starting from the Zel'dovich approximation to…

Astrophysics · Physics 2015-06-24 Matthias Steinmetz , Matthias Bartelmann

We use numerical simulations to examine the substructure within galactic and cluster mass halos that form within a hierarchical universe. Clusters are easily reproduced with a steep mass spectrum of thousands of substructure clumps that…

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