Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants, Dwarfs, and Nuclei from ACS Imaging

We report the discovery of 4 candidate intracluster globular clusters (IGCs) in a single deep HST ACS field of the Virgo Cluster. We show that each cluster is roughly spherical, has a magnitude near the peak of the Virgo globular cluster luminosity function, has a radial profile that is best-fit by a King model, and is surrounded by an excess of point sources which have the colors and magnitudes of cluster red giant stars. Despite the fact that two of our IGC candidates have ...

We examine the correlation between globular cluster (GC) color and magnitude using HST/ACS imaging for a sample of 79 early-type galaxies (-21.7<M_B<-15.2 mag) with accurate SBF distances from the ACS Virgo Cluster Survey. Using the KMM mixture modeling algorithm, we find a highly significant correlation, d(g-z)/dz = -0.037 +- 0.004, between color and magnitude for the subpopulation of blue GCs in the co-added GC color-magnitude diagram of the three brightest Virgo galaxies (...

We present the results of a Hubble Space Telescope WFPC2 F555W and F814W survey of 69 dwarf elliptical galaxies (dEs) in the Virgo and Fornax Clusters and Leo Group. The $V-I$ colors of the dE globular clusters, nuclei, and underlying field star populations are used to trace the dE star-formation histories. We find that the dE globular cluster candidates are as blue as the metal-poor globular clusters of the Milky Way. The observed correlation of the dE globular cluster syste...

With the aim of finding evidence of tidal stripping of globular clusters (GCs) we analysed a sample of 13 elliptical galaxies taken from the ACS Virgo Cluster Survey (VCS). These galaxies belong to the main concentration of the Virgo cluster (VC) and present absolute magnitudes $-18.5<M_z<-22.5$. We used the public GC catalog of Jord\'an et al. (2008) and separated the GC population into metal poor (blue) and metal rich (red) according to their integrated colors. The galaxy p...

We present g and z photometry and size estimates for globular clusters (GCs) in the massive Virgo elliptical NGC 4649 (M60) using a five-pointing Hubble Space Telescope/Advanced Camera for Surveys mosaic. The metal-poor GCs show a monotonic negative metallicity gradient of (-0.43 +/- 0.10) dex per dex in radius over the full radial range of the data, out to ~ 24 kpc. There is evidence for substantial color substructure among the metal-rich GCs. The metal-poor GCs have typical...

We present in this paper the deepest Arecibo HI observations of Virgo cluster dwarf ellipticals (dEs) taken to date. Based on this data we argue that a significant fraction of Virgo cluster dEs recently underwent evolution. Our new observations consist of HI 21-cm line observations for 22 classified dE galaxies with optical radial velocities consistent with membership in the Virgo cluster. Cluster members VCC 390 and VCC 1713 are detected with HI masses M(HI) = 6*10^7 M_solar...

We report the discovery of significant localized structures in the projected two-dimensional (2D) spatial distributions of the Globular Cluster (GC) systems of the ten brightest galaxies in the Virgo Cluster. We use catalogs of GCs extracted from the HST ACS Virgo Cluster Survey (ACSVCS) imaging data, complemented, when available, by additional archival ACS data. These structures have projected sizes ranging from $\sim\!5$ arcsec to few arc-minutes ($\sim\!1$ to $\sim\!25$ kp...

We investigate the connection between globular clusters and ultra-compact dwarf galaxies (UCDs) by examining the properties of several compact objects associated with M87, all of which were previously classified as globular clusters. Combining imaging from the Hubble Space Telescope with ground-based Keck spectroscopy, we find two objects to have half-light radii, velocity dispersions and mass-to-light ratios that are consistent with the predictions of population synthesis mo...

(ABRIDGED) The ACS camera on board the Hubble Space Telescope has been used to obtain deep images of the giant elliptical galaxy NGC 3610, a well-established dissipative galaxy merger remnant. These observations supersede previous WFPC2 images which revealed the presence of a population of metal-rich globular clusters (GCs) of intermediate age (~1.5-4 Gyr). We detect a total of 580 GC candidates, 46% more than from the previous WFPC2 images. The new photometry strengthens the...

We present a kinematic analysis of the globular cluster (GC) system in the giant elliptical galaxy (gE) M60 in the Virgo cluster. Using the photometric and spectroscopic database of 121 GCs (83 blue GCs and 38 red GCs), we have investigated the kinematics of the GC system. We have found that the M60 GC system shows a significant overall rotation. The rotation amplitude of the blue GCs is slightly smaller than or similar to that of the red GCs, and their angles of rotation axe...