A5039347456- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Black Holes and Theoretical Physics
- Remote Sensing in Agriculture
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Neutrino Physics Research
- Computer Graphics and Visualization Techniques
- Astronomical Observations and Instrumentation
- Earth Systems and Cosmic Evolution
- Computational Physics and Python Applications
Leibniz Institute for Astrophysics Potsdam
2016-2025
Observatoire astronomique de Strasbourg
2018-2019
Leibniz Association
2013-2016
Leibniz Institute for Neurobiology
2011-2014
American Institute of Physics
2011
Universidad Autónoma de Madrid
2009
Hebrew University of Jerusalem
2009
Universidad Nacional Autónoma de México
2003
New Mexico State University
1999
Astronomical Observatory of Rome
1993
Predicting structural properties of dark matter haloes is one the fundamental goals modern cosmology. We use suite MultiDark cosmological simulations to study evolution halo density profiles, concentrations, and velocity anisotropies. find that in order understand structure make 1–2 per cent accurate predictions for needs realize concentration more complex than ratio virial radius core Navarro–Frenk–White (NFW) profile. For massive haloes, average profile far from NFW shape defined by both...
We analyze the halo occupation distribution (HOD), probability for a of mass M to host number subhalos N, and two-point correlation function galaxy-size dark matter halos using high-resolution dissipationless simulations concordance flat LCDM model. The samples include both subhalos, distinct gravitationally-bound within virialized regions larger systems. find that first moment HOD, (M), has complicated shape consisting step, shoulder, power law high-mass tail. HOD can be described by...
We measure the clustering of dark matter halos in a large set collisionless cosmological simulations flat LCDM cosmology. Halos are identified using spherical overdensity algorithm, which finds mass around isolated peaks density field such that mean is Delta times background. calibrate fitting functions for scale bias adaptable to any value we examine. find ~6% scatter about our best fit relation. Our couple halo Tinker et. al. (2008) all normalized unity. demonstrate massive, rare higher...
We present analysis of the evolution dark matter halos in dense environments groups and clusters dissipationless cosmological simulations. The premature destruction such environments, known as "the overmerging," reduces predictive power N-body simulations makes difficult any comparison between models observations. analyze possible processes that cause overmerging assess extent to which this problem can be cured with current computer resources codes. Using both analytic estimates...
[abridged] We present a detailed comparison of fundamental dark matter halo properties retrieved by substantial number different finders. These codes span wide range techniques including friends-of-friends (FOF), spherical-overdensity (SO) and phase-space based algorithms. further introduce robust (and publicly available) suite test scenarios that allows finder developers to compare the performance their against those presented here. This set includes mock haloes containing various levels...
The cosmic web is one of the most striking features distribution galaxies and dark matter on largest scales in Universe. It composed dense regions packed full galaxies, long filamentary bridges, flattened sheets vast low-density voids. study has focused primarily identification such features, understanding environmental effects galaxy formation halo assembly. As such, a variety different methods have been devised to classify – depending data at hand, be it numerical simulations, large sky...
We present a study of the clustering and halo occupation distribution Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies in redshift range 0.43 < z 0.7 drawn from Final SDSS-III Data Release. compare BOSS results with predictions abundance matching (HAM) model that assigns to dark matter haloes selected large BigMultiDark N-body simulation flat Λ cold Planck cosmology. observational data simulated ones on light cone constructed 20 subsequent outputs simulation. Observational...
Cosmic reionization by starlight from early galaxies affected their evolution, thereby impacting reionization, itself. Star formation suppression, for example, may explain the observed underabundance of Local Group dwarfs relative to N-body predictions Cold Dark Matter. Reionization modelling requires simulating volumes large enough [~(100Mpc)^3] sample "patchiness", while resolving millions galaxy sources above ~10^8 Msun , combining gravitational and gas dynamics with radiative transfer....
We introduce the THE THREE HUNDRED project, an endeavour to model 324 large galaxy clusters with full-physics hydrodynamical re-simulations. Here we present data set and study differences observations for fundamental cluster properties scaling relations. find that modelled are generally in reasonable agreement respect baryonic fractions gas relations at redshift z = 0. However, there still some (model-dependent) differences, such as central galaxies being too massive, colours (g - r) bluer...
ABSTRACT Cosmic Dawn II (CoDa II) is a new, fully coupled radiation-hydrodynamics simulation of cosmic reionization and galaxy formation their mutual impact, to redshift z &lt; 6. With 40963 particles cells in 94 Mpc box, it large enough model global its feedback on while resolving all haloes above 108 M⊙. Using the same hybrid CPU–GPU code RAMSES–CUDATON as CoDa I Ocvirk et al. (2016), modified re-calibrated subgrid star algorithm, making end earlier, at ≳ 6, thereby better matching...
The James Webb Space Telescope (JWST) has uncovered an abundance of z>10 galaxies bright in the ultraviolet (UV), whose presence poses a challenge to traditional theoretical models at high redshifts. Various new have recently emerged address this discrepancy by refining their description star formation. Here, we investigate whether modifications stellar initial mass function (IMF) alone can reproduce UV luminosity functions (UV LFs) when formation rate is used as proxy for fraction...
We study the structure formation in cosmological void regions using high-resolution hydrodynamical simulations. Despite being significantly underdense, voids are populated abundantly with small dark matter haloes which should appear as dwarf galaxies if their star is not suppressed significantly. here investigate to extent ultraviolet (UV) background reduces baryon content of galaxies, and thereby limits cooling rates. Assuming a Haardt & Madau UV reionization at redshift z= 6, our samples...
A dynamical classification of the cosmic web is proposed. The large scale environment classified into four types: voids, sheets, filaments and knots. based on evaluation deformation tensor, i.e. Hessian gravitational potential, a grid. counting number eigenvalues above certain threshold, lambda_th at each grid point, where case zero, one, two or three such corresponds to void, sheet, filament knot point. collection neighboring points, friends-of-friends, same attribute constitutes knots as...
Despite a history that dates back at least quarter of century, studies voids in the large-scale structure Universe are bedevilled by major problem: there exist large number quite different void-finding algorithms, fact has so far got way groups comparing their results without worrying about whether such comparison makes sense. Because recent increased interest voids, both very galaxy surveys and detailed simulations cosmic formation, this situation is unfortunate. We here present first...
The authors derive field equations for sixth-order gravity with the Lagrangian containing terms R Square Operator and R2 show its conformal equivalence to Einstein theory two interacting scalar fields. Their masses are calculated in weak-field limit. This is generalised higher order linearised case. Inflationary regimes investigated.
The ever increasing size and complexity of data coming from simulations cosmic structure formation demands equally sophisticated tools for their analysis. During the past decade, art object finding in these has hence developed into an important discipline itself. A multitude codes based upon a huge variety methods techniques have been spawned yet question remained as to whether or not they will provide same (physical) information about structures interest. Here we summarize extent previous...
We present a detailed study of the redshift evolution dark matter halo structural parameters in LambdaCDM cosmology. mass and dependence concentration, shape spin parameter Nbody simulations spanning masses from 10^{10} Msun/h to 10^{15} redshifts 0 2. series fitting formulas that accurately describe time concentration-mass relation since z=2. Using arguments based on spherical collapse model we behaviour scale length density profile during assembly history haloes, obtaining physical...
A new approach for the classification of cosmic web is presented. In extension previous work Hahn et al. (2007) and Forero-Romero (2009) algorithm based on analysis velocity shear tensor rather than gravitational tidal tensor. The procedure consists construction at each (grid) point in space evaluation its three eigenvectors. given classified to be either a void, sheet, filament or knot according number eigenvalues above certain threshold, 0, 1, 2, 3 respectively. threshold treated as free...
We present the online MultiDark Database -- a Virtual Observatory-oriented, relational database for hosting various cosmological simulations. The data is accessible via an SQL (Structured Query Language) query interface, which also allows users to directly pose scientific questions, as shown in number of examples this paper. Further usage are given its extensive documentation (www.multidark.org). based on same technology Millennium Database, fact that will greatly facilitate both suites...
The friends-of-friends algorithm (hereafter, FOF) is a percolation which routinely used to identify dark matter halos from N-body simulations. We use results theory show that the boundary of FOF does not correspond single density threshold but range densities close critical value depends upon linking length parameter, b. for commonly choice b = 0.2, this equal 81.62 times mean density. Consequently, identified by enclose an average overdensity on their profile (concentration) and therefore...
We present an analysis of the MUSIC-2 N-body/hydrodynamical simulations aimed at estimating expected concentration–mass relation for CLASH (Cluster Lensing and Supernova Survey with Hubble) cluster sample. study nearly 1,400 halos simulated high spatial mass resolution. shape both their density surface-density profiles fit them a variety radial functions, including Navarro–Frenk–White (NFW), generalized NFW, Einasto profiles. derive concentrations masses from these fits. produce Chandra...
The alignment of DM halos and the surrounding large scale structure (LSS) is examined in context cosmic web. Halo spin, shape orbital angular momentum subhaloes investigated relative to LSS using eigenvectors velocity shear tensor evaluated on a grid with 1 Mpc/h, deep within non-linear regime. Knots, filaments, sheets voids are associated regions that collapsing along 3, 2, or 0 principal directions simultaneously. Each halo tagged web classification (i.e. knot halo, filament etc) according...
We present results on the clustering of 282 068 galaxies in Baryon Oscillation Spectroscopic Survey (BOSS) sample massive with redshifts 0.4 < z 0.7 which is part Sloan Digital Sky III project. Our cover a large range scales from ∼500 to ∼90 h−1 Mpc. compare these estimates expectations flat Λ cold dark matter (ΛCDM) standard cosmological model parameters compatible Wilkinson Microwave Anisotropy Probe 7 data. use MultiDark simulation, one largest N-body runs presently available, together...
ABSTRACT The James Webb Space Telescope (JWST) is expected to observe galaxies at z &gt; 10 that are presently inaccessible. Here, we use a self-consistent empirical model, the universemachine, generate mock galaxy catalogues and light-cones over redshift range = 0−15. These data include realistic properties (stellar masses, star formation rates, UV luminosities), galaxy–halo relationships, galaxy–galaxy clustering. Mock observables also provided for different model parameters spanning...
We present results from the semi-analytic model of galaxy formation SAG applied on MultiDark simulation MDPL2. features an updated supernova (SN) feedback scheme and a robust modelling environmental effects satellite galaxies. This incorporates gradual starvation hot gas halo driven by action ram pressure stripping (RPS), that can affect cold disc, tidal (TS), which act all baryonic components. Galaxy orbits orphan satellites are integrated providing adequate positions velocities for...