Related papers: Luminosity Function of Faint Globular Clusters in …
Following a number of conflicting studies of M87's mass profile, we undertake a dynamical analysis of multiple tracer populations to constrain its mass over a large radius range. We combine stellar kinematics in the central regions with the…
We present the results of our detailed WFPC2-based photometric study of the globular cluster systems (GCS) of over 60 elliptical and S0 galaxies. Approximately 50\% of the GCSs of ellipticals, and at least 15-20\% of S0s reveal bimodality…
Analysing the weak lensing distortions of the images of faint background galaxies provides a means to constrain the average mass distribution of cluster galaxies and potentially to test the extent of their dark matter haloes as a function…
High mass galaxies, with halo masses $M_{200} \ge 10^{10} M_{\odot}$, reveal a remarkable near-linear relation between their globular cluster (GC) system mass and their host galaxy halo mass. Extending this relation to the mass range of…
We investigate the potential to improve optical tracers of cluster mass by exploiting measurements of the magnitude gap, m12, defined as the difference between the r-band absolute magnitude of the two brightest cluster members. We find that…
The relation between the total mass contained in the globular clusters of a galaxy and the mass of its dark matter halo has been found observationally to be nearly linear over five decades of mass. However, the high-mass end of this…
Cluster scaling relations are key ingredients in cluster abundance-based cosmological studies. In optical cluster cosmology, where clusters are detected through their richness, cluster-weak gravitational lensing has proven to be a powerful…
We measure the clustering of DEEP2 galaxies at z=1 as a function of luminosity on scales 0.1 Mpc/h to 20 Mpc/h. Drawing from a parent catalog of 25,000 galaxies at 0.7<z<1.3 in the full DEEP2 survey, we create volume-limited samples having…
Recent studies of nearby globular clusters have discovered excess dark mass in their cores, apparently in an extended distribution, and simulations indicate that this mass is composed mostly of white dwarfs (respectively stellar-mass black…
We have used a large format CCD camera to survey the nearby Fornax cluster and its immediate environment for low luminosity low surface brightness galaxies. Recent observations indicate that these are the most dark matter dominated galaxies…
The gravitational lensing constraints on the small mass end of the LCDM mass function are discussed. Here a conservative approach is taken where only the most difficult to explain image flux anomalies in strong QSO lenses are emphasized.…
We present deep composite luminosity functions in $B$, $g$, $V$, $r$, $i$ and $z$ for six clusters at $0.14 < z < 0.40$ observed with the Hubble Space Telescope Advanced Camera for Surveys. The luminosity functions reach to absolute…
Low-mass stars, those with main-sequence lifetimes that are of order the age of the Universe, provide unique constraints on the Initial Mass Function (IMF) when they formed. Star counts in systems with simple star-formation histories are…
We have previously reported the discovery of strong gravitational lensing by faint elliptical galaxies using the WFPC2 on HST and here we investigate their potential usefulness in putting constraints on lens mass models. We compare various…
We review selected measurements of the galaxy luminosity function including the global field, the local group, the local sphere, nearby clusters (Virgo, Coma and Fornax) and clusters in general. We conclude that the overall cluster…
We present deep Hubble Space Telescope optical imaging observations of two Galactic globular clusters, 47 Tuc and M15, using the Space Telescope Imaging Spectrograph (STIS) longpass (LP) filter and the Wide Field and Planetary Camera 2…
Defined as X-ray bright galaxy groups with large differences between the luminosities of their brightest and second brightest galaxies, "fossil groups" are believed to be some of the oldest galaxy systems in the universe. They have…
We derive structural parameters for ~2000 globular clusters in the giant Virgo elliptical M87 using extremely deep Hubble Space Telescope images in F606W (V) and F814W (I) taken with the ACS/WFC. The cluster scale sizes (half-light radii…
The mass function of dark halos in a Lambda-dominated cold dark matter (LambdaCDM) universe is investigated. 529 output files from five runs of N-body simulations are analyzed using the friends-of-friends cluster finding algorithm. All the…
We study relation between stellar mass and halo mass for high-mass halos using a sample of galaxy clusters with accurate measurements of stellar masses from optical and IR data and total masses from X-ray observations. We find that stellar…