相关论文: Dark and visible matter distribution in Coma clust…
In the context of the CNOC1 cluster survey, redshifts were obtained for galaxies in 16 clusters. The resulting sample is ideally suited for an analysis of the internal velocity and mass distribution of clusters. Previous analyses of this…
Heavy particles in galaxy clusters tend to be more centrally concentrated than light ones according to the Boltzmann distribution. An estimate of the drift velocity suggests that it is possible that the helium nuclei may have entirely or…
(Abriged) Assuming that the hydrostatic equilibrium holds between the intracluster medium and the gravitational potential, we constrain the NFW profiles in a sample of 44 X-ray luminous galaxy clusters observed with XMM-Newton in the…
We consider the inference of the cosmic radiation density, traditionally parameterised as the effective number of neutrino species N_eff, from precision cosmological data. Paying particular attention to systematic effects, notably…
The density profiles established in the self-similar dynamical phase of dark matter haloes recollapse are all close to isothermal. This is steeper than the predictions of some n-body simulations for the central regions of the halo, which…
Using a penalised maximum likelihood we estimate, for the first time, the velocity distribution of white dwarfs in the Solar neighbourhood. Our sample consists of 129 675 white dwarfs within 500 pc in Gaia Early Data Release 3 The white…
The dynamical friction timescale of massive globular clusters (GCs) in the inner regions of cuspy dark haloes in dwarf spheroidal (dSph) galaxies can be much shorter than the Hubble time. This implies that a small fraction of the GCs is…
We assemble and observe a sample of poor galaxy systems that is suitable for testing N-body simulations of hierarchical clustering (Navarro, Frenk, & White 1997; NFW) and other dynamical halo models (e.g., Hernquist 1990). We (1) determine…
Elliptical galaxies are modelled as Sersic luminosity distributions with density profiles (DPs) for the total mass adopted from the DPs of haloes within dissipationless LambdaCDM N-body simulations. Ellipticals turn out to be inconsistent…
With the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, we have discovered in M4 (NGC 6121, C 1620-264) the first extensive sequence of cooling white dwarfs seen in a globular cluster. Adopting a distance modulus of…
We have discovered both a red and a blue subpopulation of Ultra-Compact Dwarf (UCD) galaxy candidates in the Coma galaxy cluster. We analyzed deep F475W (Sloan g) and F814W (I) Hubble Space Telescope images obtained with the Advanced Camera…
Discoveries of extended rotation curves have suggested the presence of dark matter in spiral galaxy haloes. It has led to many studies that estimated the galaxy total mass, mostly by using the Navarro Frenk and White (NFW) density profile.…
The spatial and kinematic distribution of warm gas in and around the Coma Cluster is presented through observations of Lyman-alpha absorbers using background QSOs. Updates to the Lyman-alpha absorber distribution found in Yoon et al. (2012)…
In this paper, we construct the circular velocity curve of the Milky Way out to $\sim 30$ kpc, providing an updated model of the dark matter density profile. We derive precise parallaxes for 120,309 stars with a data-driven model, using…
Aims. We determine masses and mass-to-light ratios of five ultra-compact dwarf galaxies and one dwarf elliptical nucleus in the Fornax cluster from high resolution spectroscopy. Methods. Velocity dispersions were derived from selected…
We have detected the weak lensing signal induced by the cluster of galaxies MS 2053-04 (z=0.58) from a two-colour mosaic of 6 HST WFPC2 images. The best fit singular isothermal sphere model to the observed tangential distortion yields an…
The magnification of distant sources by mass clumps at lower ($z \leq 1$) redshifts is calculated analytically. The clumps are initially assumed to be galaxy group isothermal spheres with properties inferred from an extensive survey. The…
We determine the inner density profiles of massive galaxy clusters (M$_{200}$ > $5 \times 10^{14}$ M$_{\odot}$) in the Cluster-EAGLE (C-EAGLE) hydrodynamic simulations, and investigate whether the dark matter density profiles can be…
We have measured redshifts and Kron-Cousins R-band magnitudes for a sample of galaxies in the poor cluster AWM 7. We have measured redshifts for 172 galaxies; 106 of these are cluster members. We determine the luminosity function from a…
Weak gravitational lensing provides a direct way to study the mass distribution of clusters of galaxies at large radii. Unfortunately, large scale structure along the line of sight also contributes to the lensing signal, and consequently…