The ART of Cosmological Simulations (2008)
Gottloeber, Stefan, Klypin, Anatoly
We describe the basic ideas of MPI parallelization of the N-body Adaptive Refinement Tree (ART) code. The code uses self-adaptive domain decomposition where boundaries of the domains...
Toward a halo mass function for precision cosmology: the limits of universality (2008)
Tinker, Jeremy L, Kravtsov, Andrey V, Klypin, Anatoly, Abazajian, Kevork, Warren, Michael S, Yepes, Gustavo, ...
We measure the mass function of dark matter halos in a large set of collisionless cosmological simulations of flat LCDM cosmology and investigate its evolution at z
The distribution function of dark matter in massive haloes (2008)
Wojtak, Radoslaw, Lokas, Ewa L., Mamon, Gary A., Gottloeber, Stefan, Klypin, Anatoly, Hoffman, Yehuda
We study the distribution function (DF) of dark matter particles in haloes of mass range 10^{14}--10^{15}\Msun. In the numerical part of this work we measure the DF for a sample of relaxed haloes...
The role of stellar feedback in the formation of galaxies (2007)
Ceverino, Daniel, Klypin, Anatoly
We develop a new realistic prescription for modeling the stellar feedback, which minimizes any ad hoc assumptions about sub-grid physics. We start with developing high resolution models of the ISM...
The role of Stellar Feedback in the formation of galactic disks and bulges in a LCDM Universe (2007)
Ceverino, Daniel, Klypin, Anatoly
Although supernova explosions and stellar winds happens at scales bellow 100 pc, they affect the interstellar medium(ISM) and galaxy formation. We use cosmological N-body+Hydrodynamics simulations of...
The Fossil Phase in the Life of a Galaxy Group (2007)
D'Onghia, Elena, Gottloeber, Stefan, Hoeft, Matthias, Khalatyan, Arman, Klypin, Anatoly, ...
We investigate the origin and evolution of fossil groups in a concordance LCDM cosmological simulation. We consider haloes with masses between $(1-5)\times10^{13} \hMsun$ and study the physical...
Properties of voids in the Local Volume (2007)
Tikhonov, Anton, Klypin, Anatoly
Current explanation of the overabundance of dark matter subhalos in the Local Group (LG) indicates that there maybe a limit on mass of a halo, which can host a galaxy. This idea can be tested using...
Resonances in Barred Galaxies (2007)
Ceverino, Daniel, Klypin, Anatoly
The inner parts of many spiral galaxies are dominated by bars. These are strong non-axisymmetric features which significantly affect orbits of stars and dark matter particles. One of the main effects...
Conroy, Charlie, Prada, Francisco, Newman, Jeffrey A., Croton, Darren, Coil, Alison L., Conselice, Christopher J., ...
We measure the evolution in the virial mass-to-light ratio (M 200/LB) and virial-to-stellar mass ratio (M 200/M*) for isolated ∼L* galaxies between z ∼ 1 and z ∼ 0 by combining data...
Evolution in the Halo Masses of Isolated Galaxies between z~1 and z~0: From DEEP2 to SDSS (2006)
Conroy, Charlie, Prada, Francisco, Newman, Jeffrey A., Croton, Darren, Coil, Alison L., Conselice, Christopher J., ...
We measure the evolution in the virial mass-to-light ratio (M_{200}/L_B) and virial-to-stellar mass ratio (M_{200}/M_\ast) for isolated ~ L* galaxies between z~1 and z~0 by combining data from the...
The alignment of dark matter halos with the cosmic web (2006)
Patiri, Santiago G., Cuesta, Antonio J., Prada, Francisco, Betancort-Rijo, Juan, Klypin, Anatoly
We investigate the orientation of the axes and angular momentum of dark matter halos with respect to their neighboring voids using high resolution N-body cosmological simulations. We find that the...
The Properties of Galaxies in Voids (2006)
Patiri, Santiago G., Prada, Francisco, Holtzman, Jon, Klypin, Anatoly, Betancort-Rijo, Juan
We present a comparison of the properties of galaxies in the most underdense regions of the Universe, where the galaxy number density is less than 10% of the mean density, with galaxies from more...
Valenzuela, Octavio, Rhee, George, Klypin, Anatoly, Governato, Fabio, Stinson, Gregory, Quinn, Thomas, ...
Two well studied dwarf galaxies -- NGC 3109 and NGC 6822 -- present some of the strongest observational support for a flat core at the center of galactic dark matter (DM) halos. We use detailed...
Statistics of Voids in the 2dF Galaxy Redshift Survey (2005)
Patiri, Santiago G., Betancort-Rijo, Juan, Prada, Francisco, Klypin, Anatoly, Gottlöber, Stefan
We present a statistical analysis of voids in the 2dF galaxy redshift survey (2dFGRS). In order to detect the voids, we have developed two robust algorithms. We define voids as non-overlapping...
The role of resonances in barred galaxies (2005)
Ceverino, Daniel, Klypin, Anatoly
The dynamics of the inner disk of many galaxies is dominated by bars. As a result, resonances between the bar and the disk become an important factor. In order to detect resonances, we measure...
Astrophysical inputs on the SUSY dark matter annihilation detectability (2004)
Prada, Francisco, Klypin, Anatoly, Flix, J., Martinez, M., Simonneau, E.
If dark matter (DM), which is considered to constitute most of the mass of galaxies, is made of supersymmetric (SUSY) particles, the centers of galaxies should emit gamma-rays produced by their...
The rotation curves of dwarf galaxies: a problem for Cold Dark Matter? (2003)
Rhee, George, Valenzuela, Octavio, Klypin, Anatoly, Holtzman, Jon, Moorthy, Bhasker
We address the issue of accuracy in recovering density profiles from observations of rotation curves of galaxies. We ``observe'' and analyze our models in much the same way as observers do the real...
Gottloeber, Stefan, Lokas, Ewa, Klypin, Anatoly, Hoffman, Yehuda
Using high resolution N-body simulations we address the problem of emptiness of giant 20 Mpc/h diameter voids found in the distribution of bright galaxies. Are the voids filled by dwarf galaxies? Do...
Observing the dark matter density profile of isolated galaxies (2003)
Prada, Francisco, Vitvitska, Mayrita, Klypin, Anatoly, Holtzman, Jon A., Schlegel, David J., Grebel, Eva K., ...
Using the Sloan Digital Sky Survey (SDSS), we probe the halo mass distribution by studying the velocities of satellites orbiting isolated galaxies. In a subsample that covers 2500 sq. degrees on the...
Cusps, satellites, and resonances Elektronische Daten (2003)
Klypin, Anatoly, Valenzuela, Octavio, Astrophysics Conference
Talk Abstract von Kongress: Star and Structure Formation: From First Light to the Milky Way, Astrophysics Conference, August 18-22, 2003, ETH Zurich, Switzerland
Formation and evolution of DM halos in different environment Elektronische Daten (2003)
Gottlöber, Stefan, Klypin, Anatoly, Astrophysics Conference
Talk Abstract von Kongress: Star and Structure Formation: From First Light to the Milky Way, Astrophysics Conference, August 18-22, 2003, ETH Zurich, Switzerland
Observing the dark matter density profile of isolated galaxies (2003)
Prada, Francisco, Vitvitska, Mayrita, Klypin, Anatoly, Holtzman, Jon A., Schlegel, David J., Grebel, Eva K., ...
Using the Sloan Digital Sky Survey (SDSS), we probe the halo mass distribution by studying the velocities of satellites orbiting isolated galaxies. In a subsample that covers 2500 deg2 on the sky, we...
Simulations of the Local Universe (2002)
Gottloeber, Stefan, Klypin, Anatoly, Kravtsov, Andrey, Hoffman, Yehuda, Faltenbacher, Andreas
The theory of structure formation predicts that galaxies form within extended massive dark matter halos built from smaller pieces that collided and merged, resulting in the hierarchy of galaxies,...
Low mass dark matter halos in voids (2002)
Gottloeber, Stefan, Lokas, Ewa, Klypin, Anatoly
Using numerical simulations and the Sheth-Tormen approximation we study the mass function of dark matter halos in voids. We find that the void mass function is significantly lower and its shape is...
Secular bar formation in galaxies with significant amount of dark matter (2002)
Valenzuela, Octavio, Klypin, Anatoly
Using high resolution N-body simulations of stellar disks embedded in cosmologically motivated dark matter halos, we study the evolution of bars and the transfer of angular momentum between halos and...
Spatial distribution of galactic halos and their merger histories (2002)
Gottloeber, Stefan, Kerscher, Martin, Kravtsov, Andrey V., Faltenbacher, Andreas, Klypin, Anatoly, Mueller, Volker
We use a novel statistical tool, the mark correlation functions (MCFs), to study clustering of galaxy-size halos as a function of their properties and environment in a high-resolution numerical...
Sloan Digital Sky Survey: Early data release (2002)
Stoughton, Chirs, Lupton, Rpbert H., Bernardi, Mariangela, Blanton, Michael R., Burles, Scott, Castander, Francsico J., ...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of 10 6 galaxies, 100,000...
Sloan Digital Sky Survey: early data release (2002)
Stoughton, Chris, Lupton, Robert H., Bernardi, Mariangela, Blanton, Michael R., Burles, Scott M., Castander, Francisco J., ...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of ≈ 106 galaxies,...
Sloan Digital Sky Survey: early data release (2002)
Stoughton, Chris, Lupton, Robert H., Bernardi, Mariangela, Blanton, Michael R., Burles, Scott M., Castander, Francisco J., ...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of ≈ 106 galaxies,...
LCDM-based models for the Milky Way and M31 I: Dynamical Models (2001)
Klypin, Anatoly, Zhao, HongSheng, Somerville, Rachel S.
We apply standard disk formation theory with adiabatic contraction within cuspy halo models predicted by the standard LCDM cosmology. The resulting models score remarkably well when confronted with...
Constrained Simulations of the Real Universe: the Local Supercluster (2001)
Klypin, Anatoly, Hoffman, Yehuda, Kravtsov, Andrey, Gottloeber, Stefan
We present cosmological simulations which closely mimic the real Universe within 100Mpc of the Local Group. The simulations, called Constrained Simulations, reproduce the large-scale density field...
Resolving the Structure of Cold Dark Matter Halos II (2000)
Klypin, Anatoly, Kravtsov, Andrey V., Bullock, James, Primack, Joel
We study the effects of mass and force resolution on the density profiles of galaxy-size Cold Dark Matter (CDM) halos in a flat, low-density cosmological model with vacuum energy. We show...
Numerical Simulations in Cosmology I: Methods (2000)
This lecture gives a short introduction to different methods used in cosmology. The focus is on major features of N-body simulations: equations, main numerical techniques, effects of resolution, and...
Numerical Simulations in Cosmology II: Spatial and Velocity Biases (2000)
We give a summary of recent results on spatial and velocity biases in cosmological models. Progress in numerical techniques made it possible to simulate halos in large volumes with a such accuracy...
Numerical Simulations in Cosmology III: Dark Matter Halos (2000)
Properties of dark matter halos are reviewed. Taken from different publications, we present results on (1) the mass and velocity functions, (2) density and velocity profiles, and (3) concentration of...
Simulated Cluster Archive: A Computational Catalog of X-Ray Clusters in a Lambda-CDM Universe (2000)
Norman, Michael L., Daues, Greg, Nelson, Erik, Loken, Chris, Burns, Jack, Bryan, Greg, ...
We have simulated the evolution of a large sample of X-ray clusters in a Lambda-CDM universe at high spatial resolution using adaptive mesh refinement and placed the results in an online archive for...
Merging history as a function of halo environment (2000)
Gottloeber, Stefan, Klypin, Anatoly, Kravtsov, Andrey
According to the hierarchical scenario, galaxies form via merging and accretion of small objects. Using N-body simulations, we study the frequency of merging events in the history of the halos. We...
On effects of resolution in dissipationless cosmological simulations (1999)
Knebe, Alexander, Kravtsov, Andrey V., Gottloeber, Stefan, Klypin, Anatoly
We present a study of numerical effects in dissipationless cosmological simulations. The numerical effects are evaluated and studied by comparing results of a series of 64^3-particle simulations of...
Spatial and Velocity Biases (1999)
Klypin, Anatoly, Kravtsov, Andrey V., Colin, Pedro
We give a summary of our recent studies of spatial and velocity biases of galaxy-size halos in cosmological models. Recent progress in numerical techniques made it possible to simulate halos in large...
Merging Rate of Dark Matter Halos: Evolution and Dependence on Environment (1999)
Gottloeber, Stefan, Klypin, Anatoly, Kravtsov, Andrey V.
We discuss the impact of the cosmological environment on the evolution of dark matter halos using a high-resolution simulation within a spatially flat LCDM cosmology.
Velocity bias in a LCDM model (1999)
Colin, Pedro, Klypin, Anatoly, Kravtsov, Andrey V.
We use N-body simulations to study the velocity bias of dark matter halos, the difference in the velocity fields of dark matter and halos, in a flat low- density LCDM model. The high force, 2kpc/h,...
Origin and evolution of halo bias in linear and non-linear regimes (1998)
Kravtsov, Andrey, Klypin, Anatoly
We present results from a study of bias and its evolution for galaxy-size halos in a large, high-resolution simulation of a LCDM model. We consider the evolution of bias estimated using two-point...
Evolution of isolated halos and halos inside of groups and clusters in a LCDM model (1998)
Gottloeber, Stefan, Klypin, Anatoly, Kravtsov, Andrey
A significant fraction of mass in the universe is believed to be in the form of dark matter (DM). Due to gravitational instability, the DM collapses hierarchically into DM halos. In this contribution...
Evolution of halo-halo clustering and bias in a LCDM model (1998)
Kravtsov, Andrey, Klypin, Anatoly, Colin, Pedro, Khokhlov, Alexei
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...
Numerical Simulations of Galaxy Formation: Cooling, Heating, Star Formation (1997)
Klypin, Anatoly, Gottlober, Stefan, Yepes, Gustavo
Formation of luminous matter in the Universe is a complicated process, which includes many processes and components. It is the vastly different scales involved in the process (from star formation on...
Particle-Mesh code for cosmological simulations (1997)
Klypin, Anatoly, Holtzman, Jon
Particle-Mesh (PM) codes are still very useful tools for testing predictions of cosmological models in cases when extra high resolution is not very important. We release for public use a cosmological...
CDM-Variant Cosmological Models - I: Simulations and Preliminary Comparisons (1997)
Gross, Michael A. K., Somerville, Rachel S., Primack, Joel R., Holtzman, Jon, Klypin, Anatoly
We present two matched sets of five simulations each, covering five presently favored simple modifications to the standard cold dark matter (CDM) scenario. One simulation suite, with a linear box...
Galaxies in N-body simulations: overcoming the overmerging problem (1997)
Klypin, Anatoly, Gottloeber, Stefan, Kravtsov, Andrey, Khokhlov, Alexei
We present analysis of the evolution of dark matter halos in dense environments of groups and clusters in dissipationless cosmological simulations. The premature destruction of halos in such...
Linearizing the Observed Power Spectrum (1997)
Smith, Clay, Klypin, Anatoly, Gross, Michael, Primack, Joel, Holtzman, Jon
Reconstruction of the linear power spectrum from observational data provides a way to compare cosmological models to a large amount of data, as Peacock & Dodds (1994, 1996) have shown. By applying...
Davé, Romeel, Hellinger, Doug, Primack, Joel, Nolthenius, Richard, Klypin, Anatoly
A new class of geometric statistics for analyzing galaxy catalogs is presented. Filament statistics quantify filamentarity and planarity in large scale structure in a manner consistent with catalog...
Primack, Joel, Klypin, Anatoly
Here we discuss what are perhaps the two most popular variants of CDM that might agree with the data: \lcdm\ and CHDM. While the predictions of COBE-normalized \lcdm\ and CHDM both agree well with...
Burns, Jack O., Ledlow, Michael J., Loken, Chris, Klypin, Anatoly, Voges, Wolfgang, Bryan, Greg L., ...
We present the first X-ray Luminosity Function (XLF) for an optically-selected sample of 49 nearby poor clusters of galaxies and a sample of 67 Abell clusters with z < 0.15. We have extended the...
Small-Scale Power Spectrum and Correlations in LCDM (1995)
Klypin, Anatoly, Primack, Joel, Holtzman, Jon
Cosmological models with a positive cosmological constant and $\Omega_0
Mixed Dark Matter Model in Halos of Clusters (1995)
Kofman, Lev, Klypin, Anatoly, Pogosyan, Dmitri, Henry, J. Patrick
We discuss the structure of clusters in a class of flat cosmological models with the fraction of mass \Omega_{CDM} ~0.8 in cold dark matter, and the rest in hot dark matter in the form of massive...
Evolution of Clusters in Cold plus Hot Dark Matter Models (1995)
Walter, Charles, Klypin, Anatoly
We use N-body simulations to study evolution of galaxy clusters over the redshift interval 0
Davé, Romeel, Hellinger, Doug, Nolthenius, Richard, Primack, Joel, Klypin, Anatoly
A new class of geometric statistics for analyzing galaxy catalogs is presented. {\it Filament statistics} quantify filamentarity and planarity in large scale structure in a manner consistent with...
Cold + Hot Dark Matter Cosmology with $m(\nu_\mu) \approx m(\nu_\tau) \approx 2.4$ ev (1994)
Primack, Joel R., Holtzman, Jon, Klypin, Anatoly, File, Uuencoded Compressed . Ps
Cold + Hot Dark Matter (CHDM) $\Omega=1$ cosmological models require a total neutrino mass $\sim 5$ eV. Because recent data support the $\nu_\mu \to \nu_\tau$ oscillation explanation of the cosmic...
Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter (1994)
Klypin, Anatoly, Borgani, Stefano, Holtzman, Jon, Primack, Joel
Damped Ly$\alpha$ systems provide possibly the most significant evidence for early structure formation, and thus a stringent constraint on the Cold + Hot Dark Matter (CHDM) cosmology. Using the...
The Evolution of X-Ray Clusters in a Cold Plus Hot Dark Matter Universe (1994)
Bryan, Greg L., Klypin, Anatoly, Loken, Chris, Norman, Michael L., Burns, Jack O.
We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a Cold + Hot Dark Matter (CHDM) model. We have performed a hydrodynamic plus N-body...
Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter (1994)
Klypin, Anatoly, Borgani, Stefano, Holtzman, Jon, Primack, Joel
Although the Cold + Hot Dark Matter (CHDM) cosmology provides perhaps the best fit of any model to all the available data at the current epoch, CHDM produces structure at relatively low redshifts and...
The Evolution of X-ray Clusters in a Cold plus Hot Dark Matter Universe (1994)
Greg L. Bryan, Anatoly Klypin, Chris Loken, Michael L. Norman, Jack O. Burns
We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a Cold + Hot Dark Matter (CHDM) model. We have performed a hydrodynamic plus N-body...
Galaxy Groups in Cold + Hot and CDM Universes: Comparison with CfA (1993)
Nolthenius, Richard, Klypin, Anatoly, Primack, Joel R.
This letter presents results of new high resolution $\Omega=1$ Cold + Hot Dark Matter (CHDM) and Cold Dark Matter (CDM) simulations. Properties of groups in these simulations reflect the lower...
We propose the zero-point of the cluster-cluster correlation function as a sensitive test for the shape of the power spectrum of initial fluctuations. It is now possible to go beyond the power law...
Structure Formation with Cold + Hot Dark Matter (1993)
Klypin, Anatoly, Holtzman, Jon, Primack, Joel, Regos, Eniko
We report results from high-resolution particle-mesh (PM) N-body simulations of structure formation in an $\Omega=1$ cosmological model with a mixture of Cold plus Hot Dark Matter (C+HDM) having...