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We investigate galaxy clustering and galaxy-mass correlations in the LCDM cosmological model using a large volume SPH simulation. For the most part, the predicted biases between galaxies and dark matter lead to good agreement with current…

Astrophysics · Physics 2009-11-07 David H. Weinberg , Romeel Dav'e , Neal Katz , Lars Hernquist

We propose a heuristic model that displays the main features of realistic theories for galaxy bias. We show that the low-order clustering statistics of the dark-matter distribution depend almost entirely on the locations and density…

Astrophysics · Physics 2011-05-05 J. A. Peacock , R. E. Smith

It has long been regarded as difficult for a cosmological model to account simultaneously for the galaxy luminosity, mass, and velocity distributions. We revisit this issue using a modern compilation of observational data along with the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Sebastian Trujillo-Gomez , Anatoly Klypin , Joel Primack , Aaron J. Romanowsky

We study the cluster mass function in mixed dark matter (MDM) models, using two COBE normalized simulations with Omega_h = 0.26 and n=1.2, and Omega_h = 0.14 and n = 1.05, both with 2 massive nu's (MDM1 and MDM2, respectively). For the sake…

Astrophysics · Physics 2009-10-31 A. Gardini , S. A. Bonometto , G. Murante

N-body simulations and analytical calculations of the gravitational collapse in an expanding universe predict that halos should form with a diverging inner density profile, the cusp. There are some observational indications that the dark…

Astrophysics · Physics 2009-11-06 Amr El-Zant , Isaac Shlosman , Yehuda Hoffman

We present a precise estimate of the bulk virial scaling relation of halos formed via hierarchical clustering in an ensemble of simulated cold dark matter cosmologies. The result is insensitive to cosmological parameters, the presence of a…

We analyse the large--scale velocity field obtained by N--body simulations of cold dark matter (CDM) models with non--Gaussian primordial density fluctuations, considering models with both positive and negative primordial skewness in the…

Astrophysics · Physics 2015-06-24 F. Lucchin , S. Matarrese , A. Messina , L. Moscardini , G. Tormen

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

Astrophysics · Physics 2009-11-06 Marcelo Alvarez , Paul R. Shapiro , Hugo Martel

We test an analytic model for the two-point correlations of galaxy clusters in redshift space using the Hubble Volume N-body simulations. The correlation function of clusters shows no enhancement along the line of sight, due to the lack of…

Astrophysics · Physics 2009-11-06 Nelson D. Padilla , Carlton M. Baugh

Discrepancies have emerged between the predictions of standard cold dark matter (CDM) theory and observations of clustering on sub-galactic scales. Warm dark matter (WDM) is a simple modification of CDM in which the dark matter particles…

Astrophysics · Physics 2009-10-31 Paul Bode , Jeremiah P. Ostriker , Neil Turok

In the CDM scenario, dark matter halos are assembled hierarchically from smaller subunits. A long-standing problem with this picture is that the number of sub-halos predicted by CDM simulations is orders of magnitudes higher than the known…

Astrophysics · Physics 2014-11-18 T. Riehm , E. Zackrisson , O. Moeller , E. Mortsell , K. Wiik

The two-year COBE-DMR 53 and 90 GHz sky maps, in both galactic and ecliptic coordinates, are used to determine the normalisation of inflationary universe models with a flat global geometry and adiabatic density perturbations. The…

Astrophysics · Physics 2015-06-24 R. Stompor , K. M. Gorski , A. J. Banday

In the last time the cold dark matter (CDM) model has suggested more and more that it is not able to describe all the properties of nearby galaxies that can be observed in great detail as well as that it has some problems in the mechanism…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Juan Magaña , Tonatiuh Matos , Victor Robles , Abril Suárez

COBE-normalized flat (matter plus cosmological constant) and open Cold Dark Matter (CDM) models are tested by comparing their expected Hubble flow variations and the observed variations in a Type Ia supernova sample and a Tully Fisher…

Astrophysics · Physics 2009-10-30 Xiangdong Shi

We perform a detailed investigation of the statistical properties of the projected distribution of galaxy clusters obtained in Cold Dark Matter (CDM) models with both Gaussian and skewed primordial density fluctuations. We use N-body…

Astrophysics · Physics 2015-06-24 S. Borgani , P. Coles , L. Moscardini , M. Plionis

We present distribution functions and spatial correlations of the shapes of dark matter halos derived from Hubble Volume simulations of a LambdaCDM universe. We measure both position and velocity shapes within spheres encompassing mean…

Astrophysics · Physics 2008-11-26 S. F. Kasun , A. E. Evrard

Cold Dark Matter (CDM) has become the standard modern theory of cosmological structure formation. Its predictions appear to be in good agreement with data on large scales, and it naturally accounts for many properties of galaxies. But…

Astrophysics · Physics 2009-11-07 Joel R. Primack

The Cold Dark Matter (CDM) theory predicts a wealth of substructure within dark halos. These predictions match observations of galaxy clusters like the nearby Virgo cluster. However, CDM has a "small scale crisis" since galaxies dominate…

Astrophysics · Physics 2009-11-10 Elena D'Onghia , George Lake

We present a series of four simulations of Cold Dark Matter (CDM) and Cold + Hot Dark Matter (CHDM) cosmologies. We discuss the power spectrum and correlation functions in real and redshift space, with comparisons to the CfA2 and IRAS…

Astrophysics · Physics 2016-08-30 A. Klypin , R. Nolthenius , J. Primack

We exmaine the distribution of hot gas in a standard CDM model of the universe using high resolution hydrodynamic simulations. Adopting standard parameters determined from COBE and light element nucleosynthesis, $\sigma_8=1.05$,…

Astrophysics · Physics 2009-10-22 Hyesung Kang , Renyue Cen , Jeremiah P. Ostriker , Dongsu Ryu