Structure of Dark Matter Halos from Hierarchical Clustering

Fukushige, Toshiyuki; Makino, Junichiro

doi:10.1086/321666

Cited by 201 publications

(209 citation statements)

References 38 publications

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“…Firstly, the universal cuspy halo density profiles Moore et al 1999;Fukushige & Makino 2001), while in agreement with observations of galaxy clusters, are in apparent Send offprint requests to: M. Samland, e-mail: samland@astro.unibas.ch disagreement with the flat dark matter density distributions inferred from observations in the centres of galaxies (Salucci & Burkert 2000;Blais-Ouellette et al 2001;Borriello & Salucci 2001;de Blok et al 2001). Secondly, the specific angular momenta and scale lengths of the disk galaxies in the cosmological simulations are too small compared to real galaxies (Navarro & Steinmetz 2000b).…”

Section: Introductionmentioning

confidence: 51%

The formation of a disk galaxy within a growing dark halo

Samland

Gerhard

2003

A&A

126

153

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Abstract. We present a dynamical model for the formation and evolution of a massive disk galaxy, within a growing dark halo whose mass evolves according to cosmological simulations of structure formation. The galactic evolution is simulated with a new three-dimensional chemo-dynamical code, including dark matter, stars and a multi-phase ISM. The simulations start at redshift z = 4.85 with a small dark halo in a ΛCDM universe and we follow the evolution until the present epoch. The energy release by massive stars and supernovae prevents a rapid collapse of the baryonic matter and delays the maximum star formation until redshift z ≈ 1. The metal enrichment history in this model is broadly consistent with the evolution of [Zn/H] in damped Lyα systems. The galaxy forms radially from inside-out and vertically from halo to disk. As a function of metallicity, we have described a sequence of populations, reminiscent of the extreme halo, inner halo, metal-poor thick disk, thick disk, thin disk and inner bulge in the Milky Way. The first galactic component that forms is the halo, followed by the bulge, the disk-halo transition region, and the disk. At redshift z ≈ 1, a bar begins to form which later turns into a triaxial bulge. Despite the still idealized model, the final galaxy resembles present-day disk galaxies in many aspects. The bulge in the model consists of at least two stellar subpopulations, an early collapse population and a population that formed later in the bar. The initial metallicity gradients in the disk are later smoothed out by large scale gas motions induced by the bar. There is a pronounced deficiency of low-metallicity disk stars due to pre-enrichment of the disk ISM with metal-rich gas from the bulge and inner disk ("G-dwarf problem"). The mean rotation and the distribution of orbital eccentricities for all stars as a function of metallicity are not very different from those observed in the solar neighbourhood, showing that early homogeneous collapse models are oversimplified. The approach presented here provides a detailed description of the formation and evolution of an isolated disk galaxy in a ΛCDM universe, yielding new information about the kinematical and chemical history of the stars and the interstellar medium, but also about the evolution of the luminosity, the colours and the morphology of disk galaxies with redshift.

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Section: Introductionmentioning

confidence: 51%

The formation of a disk galaxy within a growing dark halo

Samland

Gerhard

2003

A&A

126

153

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“…In general, the orbits of dark matter particles in simulated halos are isotropic near their centers and more radial further out (Colín et al 2000;Fukushige & Makino 2001). To explore the connection between this trend and the ROI, we calculate velocity dispersion profiles for our halos.…”

Section: Velocity Dispersionsmentioning

confidence: 99%

On Universal Halos and the Radial Orbit Instability

MacMillan

Widrow

Henriksen

2006

ApJ

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The radial orbit instability drives the density profile of a collapsing nearly spherical density perturbation toward the universal form found in cosmological simulations. This conclusion, first noted by Huss and coworkers, is explored in detail through a series of numerical experiments involving isolated halos. Simulations are run with and without the nonradial forces responsible for the instability. In the absence of the instability, the density profile is a pure power law, the differential energy distribution is close to a Boltzmann distribution, and the orbits are radially biased. The instability transforms the density profile to the NFW form, induces an energy cutoff at high binding energy, and isotropizes the orbits near the center of the system. New insights into the underlying physics of the radial orbit instability are presented. Subject headingg s: cosmology: theory -dark matter -large-scale structure of universe

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“…The N-body profiles are characterized by an r −3 decline at large radii and a cuspy profile of the form ρ(r) ∝ r −α , where α < 2 close to the center. The true value of the inner density slope α is a matter of controversy, with NFW suggesting α = 1, but with Moore et al (1998), Ghigna et al (2000), and Fukushige & Makino (2001) arguing for α = 1.5, while Jing & Suto (2000) and Klypin et al (2001) claimed that the true value of α may depend on halo mass, merger history, Article published by EDP Sciences and substructure. Power et al (2003) pointed out that the logarithmic slope becomes increasingly shallow inwards, with little sign of approaching an asymptotic value at the resolved radii.…”

Section: Introductionmentioning

confidence: 99%

Density profiles of dark matter haloes on galactic and cluster scales

Popolo

Kroupa²

2009

A&A

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Aims. In the present paper, we improve the "extended secondary infall model" (ESIM) of Williams and collaborators to obtain further insights into the cusp/core problem. Methods. A secondary infall model close to the collapse reality is obtained by simultaneously taking into account effects that till now have been studied separately, namely ordered and random angular momentum, dynamical friction, and baryon adiabatic contraction. The model is applied to structures on galactic scales (normal and dwarf spiral galaxies) and on galaxy cluster scales. Results. Our results imply that angular momentum and dynamical friction are able, on galactic scales, of overcoming the competing effect of adiabatic contraction and eliminating the Cusp. The NFW profile is not the standard outcome of the model, and it can be recovered in our model only if the system consists entirely of dark matter and the magnitude of angular momentum and dynamical friction are lower than the values predicted by the model itself. Comparison of the rotation curves of LSB galaxies with the results of our model are in good agreement. On scales smaller than 10 11 h −1 M , the slope is α 0, and on cluster scales we observe a similar evolution in the dark matter density profile but in this case the density profile slope flattens to α 0.7 for a cluster of 10 14 h −1 M . The total mass profile differs from that of dark matter showing a central cusp that is reproduced by a NFW model.

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Structure of Dark Matter Halos from Hierarchical Clustering

Cited by 201 publications

References 38 publications

The formation of a disk galaxy within a growing dark halo

The formation of a disk galaxy within a growing dark halo

On Universal Halos and the Radial Orbit Instability

Density profiles of dark matter haloes on galactic and cluster scales

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