Shapes of dark matter halos

Abstract

I present an analysis of the density shapes of dark matter halos in LCDM and LWDM cosmologies. The main results are derived from a statistical sample of galaxy-mass halos drawn from a high resolution LCDM N-body simulation. Halo shapes show significant trends with mass and redshift: low-mass halos are rounder than high mass halos, and, for a fixed mass, halos are rounder at low z. Contrary to previous expectations, which were based on cluster-mass halos and non-COBE normalized simulations, LCDM galaxy-mass halos at z=0 are not strongly flattened, with short to long axis ratios of s = 0.70 +/- 0.17. I go on to study how the shapes of individual halos change when going from a LCDM simulation to a simulation with a warm dark matter power spectrum (LWDM). Four halos were compared, and, on average, the WDM halos are more spherical than their CDM counterparts (s =0.77 compared to s = 0.71). A larger sample of objects will be needed to test whether the trend is significant.

5 pages, 2 figures, to appear in proceedings of the May 2001 Yale workshop "The Shapes of Galaxies and their Halos"

Cited by in corpus (52)

• Tracing Galaxy Formation with Stellar Halos I: Methods
• The Sagittarius Dwarf Galaxy: a Model for Evolution in a Triaxial Milky Way Halo
• The spin and shape of dark matter haloes in the Millennium simulation of a LambdaCDM universe
• The great disk of Milky-Way satellites and cosmological sub-structures
• Internal and External Alignment of the Shapes and Angular Momenta of LCDM Halos
• The Effect of Gas Cooling on the Shapes of Dark Matter Halos
• The Anisotropic Distribution of Galactic Satellites
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: III. Constraints on the Flattening of the Galactic Halo
• Velocity trends in the debris of Sagittarius and the shape of the dark-matter halo of the Galaxy
• The Galaxy and its stellar halo: insights on their formation from a hybrid cosmological approach
• The Shape of Dark Matter Haloes in the Aquarius Simulations: Evolution and Memory
• Evidence for a Triaxial Milky Way Dark Matter Halo from the Sagittarius Stellar Tidal Stream
• Chandra Evidence for a Flattened, Triaxial Dark Matter Halo in the Elliptical Galaxy NGC 720
• The shapes, orientation, and alignment of Galactic dark matter subhalos
• Probing the Shape of the Galactic Halo with Hyper-Velocity Stars
• The dependence on environment of Cold Dark Matter Halo properties
• Is the dark halo of our Galaxy spherical?
• Stellar Streams as Probes of Dark Halo Mass and Morphology: A Bayesian Reconstruction
• Are mergers responsible for universal halo properties?
• Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: the Case of Palomar 5
• Spatial and kinematic alignments between central and satellite halos
• The Alignment between Satellites and Central Galaxies: Theory vs. Observations
• The origin and tidal evolution of cuspy triaxial haloes
• Stellar Bar Evolution in Cuspy and Flat-Cored Triaxial CDM Halos
• Growing Live Disks Within Cosmologically Assembling Asymmetric Halos: Washing Out the Halo Prolateness
• Dynamical friction in flattened systems: A numerical test of Binney's approach
• Properties of Dark Matter Haloes
• The Tidal Streams of Disrupting Subhaloes in Cosmological Dark Matter Haloes
• NGC 4608 and NGC 5701: Barred Galaxies without Disks?
• Detection of satellite remnants in the Galactic Halo with Gaia - I. The effect of the Galactic background, observational errors and sampling
• On the Spiral Structure of NGC 2915 and Dark Matter
• The impact of galactic feedback on the shapes of dark-matter haloes
• An artificial neural network to discover Hypervelocity stars: Candidates in Gaia DR1/TGAS
• An Analytic Model for the Axis-Ratio Distribution of Dark Matter Halos from the Primordial Gaussian Density Field
• The impact of inelastic self-interacting dark matter on the dark matter structure of a Milky Way halo
• Spherically Averaging Ellipsoidal Galaxy Clusters in X-Ray and Sunyaev-Zel'dovich Studies: I. Analytical Relations
• Phase-space shapes of clusters and rich groups of galaxies
• The Shape of Galaxy Cluster Dark Matter Haloes: Systematics of Its Imprint on Cluster Gas, and Comparison to Observations
• The peculiar velocities of satellites of external disk galaxies
• Dynamics of Gaseous Disks in a Non-axisymmetric Dark Halo
• The Effect of Substructure on Mass Estimates of Galaxies
• A Counterpart to the Radial Orbit Instability in Triaxial Stellar Systems
• Theoretical dark matter halo kinematics and triaxial shape
• The Axis-Ratio Distribution of Galaxy Clusters in the SDSS-C4 Catalog as a New Cosmological Probe
• Dynamical measurement of the stellar surface density of face-on galaxies
• Prospects for $\gamma$-ray observations of the Perseus galaxy cluster with the Cherenkov Telescope Array
• Measurement of halo properties with weak lensing shear and flexion
• Estimate of halo ellipticity as a function of radius with flexions
• Estimation of halo ellipticity using spin-3 flexion
• Shapes of dark matter haloes with discrete globular cluster dynamics: The example of NGC 5128 (Centaurus A)
• Precision Astrometry, Galactic Mergers, Halo Substructure and Local Dark Matter
• Evolution of axis ratios from phase space dynamics of triaxial collapse