scholarly journals The dynamical state of dark matter haloes in cosmological simulations - I. Correlations with mass assembly history

2011 ◽  
Vol 419 (2) ◽  
pp. 1576-1587 ◽  
Author(s):  
Chris Power ◽  
Alexander Knebe ◽  
Steffen R. Knollmann
Keyword(s):  
Dark Matter ◽  
Cosmological Simulations ◽  
Dynamical State ◽  
Mass Assembly

scholarly journals The anisotropy of the power spectrum in periodic cosmological simulations

2021 ◽  
Vol 503 (4) ◽  
pp. 5638-5645
Author(s):  
Gábor Rácz ◽  
István Szapudi ◽  
István Csabai ◽  
László Dobos
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Power Spectra ◽  
Cosmological Simulations ◽  
Spherical Collapse ◽  
Lower Amplitude ◽  
Hydrodynamical Simulations

ABSTRACT The classical gravitational force on a torus is anisotropic and always lower than Newton’s 1/r2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard Lambda cold dark matter (ΛCDM) initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The lower amplitude of power spectra of small periodic simulations is a consequence of the missing large-scale modes and the equally important smaller periodic forces. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

scholarly journals Star formation and stellar mass assembly in dark matter haloes: from giants to dwarfs

2015 ◽  
Vol 450 (2) ◽  
pp. 1604-1617 ◽  
Author(s):  
Zhankui Lu ◽  
H. J. Mo ◽  
Yu Lu ◽  
Neal Katz ◽  
Martin D. Weinberg ◽  
...  
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Stellar Mass ◽  
Mass Assembly

scholarly journals Cosmological simulations with self-interacting dark matter – I. Constant-density cores and substructure

2013 ◽  
Vol 430 (1) ◽  
pp. 81-104 ◽  
Author(s):  
Miguel Rocha ◽  
Annika H. G. Peter ◽  
James S. Bullock ◽  
Manoj Kaplinghat ◽  
Shea Garrison-Kimmel ◽  
...  
Keyword(s):  
Dark Matter ◽  
Constant Density ◽  
Cosmological Simulations

scholarly journals A dark matter disc in three cosmological simulations of Milky Way mass galaxies

2009 ◽  
Vol 397 (1) ◽  
pp. 44-51 ◽  
Author(s):  
J. I. Read ◽  
L. Mayer ◽  
A. M. Brooks ◽  
F. Governato ◽  
G. Lake
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Cosmological Simulations

scholarly journals Energy equipartition between stellar and dark matter particles in cosmological simulations results in spurious growth of galaxy sizes

2019 ◽  
Vol 488 (1) ◽  
pp. L123-L128 ◽  
Author(s):  
Aaron D Ludlow ◽  
Joop Schaye ◽  
Matthieu Schaller ◽  
Jack Richings
Keyword(s):  
Dark Matter ◽  
Dark Matter Particle ◽  
Mass Resolution ◽  
Particle Mass ◽  
Cosmological Simulations ◽  
Massive Particles ◽  
Energy Equipartition ◽  
Mass Segregation ◽  
Baryonic Mass ◽  
The Impact

ABSTRACTThe impact of 2-body scattering on the innermost density profiles of dark matter haloes is well established. We use a suite of cosmological simulations and idealized numerical experiments to show that 2-body scattering is exacerbated in situations where there are two species of unequal mass. This is a consequence of mass segregation and reflects a flow of kinetic energy from the more to less massive particles. This has important implications for the interpretation of galaxy sizes in cosmological hydrodynamic simulations, which nearly always model stars with less massive particles than are used for the dark matter. We compare idealized models as well as simulations from the eagle project that differ only in the mass resolution of the dark matter component, but keep subgrid physics, baryonic mass resolution, and gravitational force softening fixed. If the dark matter particle mass exceeds the mass of stellar particles, then galaxy sizes – quantified by their projected half-mass radii, R50 – increase systematically with time until R50 exceeds a small fraction of the redshift-dependent mean interparticle separation, l (${\rm R_{50}} \gtrsim 0.05\times l$). Our conclusions should also apply to simulations that adopt different hydrodynamic solvers, subgrid physics, or adaptive softening, but in that case may need quantitative revision. Any simulation employing a stellar-to-dark matter particle mass ratio greater than unity will escalate spurious energy transfer from dark matter to baryons on small scales.

scholarly journals Characterizing the structure of halo merger trees using a single parameter: the tree entropy

2020 ◽  
Vol 493 (3) ◽  
pp. 4551-4569 ◽  
Author(s):  
Danail Obreschkow ◽  
Pascal J Elahi ◽  
Claudia del P Lagos ◽  
Rhys J J Poulton ◽  
Aaron D Ludlow
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Peak Height ◽  
Equal Mass ◽  
Minimum Entropy ◽  
Spin Concentration ◽  
Bell Curve ◽  
History Of ◽  
Binary Mergers ◽  
Mass Assembly

ABSTRACT Linking the properties of galaxies to the assembly history of their dark matter haloes is a central aim of galaxy evolution theory. This paper introduces a dimensionless parameter s ∈ [0, 1], the ‘tree entropy’, to parametrize the geometry of a halo’s entire mass assembly hierarchy, building on a generalization of Shannon’s information entropy. By construction, the minimum entropy (s = 0) corresponds to smoothly assembled haloes without any mergers. In contrast, the highest entropy (s = 1) represents haloes grown purely by equal-mass binary mergers. Using simulated merger trees extracted from the cosmological N-body simulation SURFS, we compute the natural distribution of s, a skewed bell curve peaking near s = 0.4. This distribution exhibits weak dependences on halo mass M and redshift z, which can be reduced to a single dependence on the relative peak height δc/σ(M, z) in the matter perturbation field. By exploring the correlations between s and global galaxy properties generated by the SHARK semi-analytic model, we find that s contains a significant amount of information on the morphology of galaxies – in fact more information than the spin, concentration, and assembly time of the halo. Therefore, the tree entropy provides an information-rich link between galaxies and their dark matter haloes.

scholarly journals Cold Dark Matter Substructure and the Heating of Galactic Disks

2003 ◽  
Vol 208 ◽  
pp. 391-392
Author(s):  
Andreea S. Font ◽  
Julio F. Navarro
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dark Matter Halo ◽  
Stellar Disk ◽  
Minor Role ◽  
Galactic Disks ◽  
Cosmological Simulations ◽  
A Minor

We investigate recent suggestions that substructure in cold dark matter (CDM) halos has potentially destructive effects on galactic disks. N-body simulations of disk/bulge models of the Milky Way, embedded in a dark matter halo with substructure similar to that found in cosmological simulations, show that tides from substructure halos play only a minor role in the dynamical heating of the stellar disk. This suggests that substructure might not preclude CDM halos from being acceptable hosts of thin stellar disks.

scholarly journals The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies

2020 ◽  
Vol 495 (3) ◽  
pp. 3002-3013 ◽  
Author(s):  
Alexander Knebe ◽  
Matías Gámez-Marín ◽  
Frazer R Pearce ◽  
Weiguang Cui ◽  
Kai Hoffmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Cluster Radius ◽  
Dynamical State ◽  
The Galaxy ◽  
Radial Orbit ◽  
Galaxy Halo ◽  
Satellite Galaxies

ABSTRACT Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.

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