If the favored hierarchical cosmological model is correct, then the Milky Way system should have accreted ∼ 100− 200 luminous satellite galaxies in the past ∼ 12 Gyr. We model this process using a hybrid semi-analytic plus N-body approach which distinguishes explicitly between the evolution of light and dark matter in accreted satellites. This distinction is essential to our ability to produce ...

Effective star formation rates in tabular form are computed which yield a prescription for the star formation activity in model galaxies as a function of ambient density, metallicity, and stellar feedback. The effects of supernova explosions on the thermal balance of the Interstellar Medium (ISM) and the presence of a multi-phase ISM are explicitly included. The resulting grid of models can be ...

We use a numerical simulation of cosmological reionization to estimate the likelihood of detecting Lyman-α emitting galaxies during the pre-reionization era. We show that it is possible to find galaxies even at z ∼ 9 that are barely affected by the dumping wing of the Gunn-Peterson absorption from the neutral IGM outside of their H II regions. The damping wing becomes rapidly more significant a...

Using the Early Data Release of the Sloan Digital Sky Survey (SDSS) we investigated the clustering properties of Low Surface Brightness (LSB) galaxies in comparison to normal, High Surface Brightness (HSB) galaxies. We selected LSB galaxies and HSB galaxies with well measured redshifts from the SDSS data base and performed three-dimensional neighbour counting analysis within spheres of radii be...

We use HST/ACS images and a photometric catalog of the COSMOS field to analyze morphologies of the host galaxies of ∼400 AGN candidates at redshifts 0.3 < z < 1.0. We compare the AGN hosts with a sample of non-active galaxies drawn from the COSMOS field to match the magnitude and redshift distribution of the AGN hosts. We perform 2-D surface brightness modeling with GALFIT to yield host galaxy ...

We study how massive halos respond to perturbations. Through numerical solution of the coupled linearized Boltzmann-Poisson equations, we find that halos can transmit and amplify disturbances over large distances within galaxies. In particular, as Weinberg has noted, the halo provides an excellent medium for transmitting disturbances from the outer regions of galaxies to the inner regions. The ...

We examine the dynamics of the stars and globular clusters in the nearby giant elliptical galaxy M87 and constrain the mass distribution, using all the available data over a large range of radii, including higher-order moments of the stellar line-of-sight velocity distributions and the discrete velocities of over two hundred globular clusters. We introduce an extension of spherical orbit modeli...

We examine the relationship between environment and the luminosities, surface brightnesses, colors, and profile shapes of luminous galaxies in the Sloan Digital Sky Survey (SDSS). For the SDSS sample, galaxy color is the galaxy property most predictive of the local environment. Galaxy color and luminosity—measures of the star formation history—jointly comprise the most predictive pair of proper...

Optical variability in galaxies at high redshift is a tracer of evolution in AGN activity, and should provide a useful constraint on models of galaxy evolution, AGN structure, and cosmology. We studied optical variability in multiple deep CCD and photographic surveys of blank fields for galaxies with Bj = 20− 25 mag. Weakly variable objects are far more common than strongly variable ones. For o...

We report the first results of our multicolour broad-band BVRI photometry for a statistically well defined sample of interacting pairs, drawn from the Catalogue of Isolated Pairs of Galaxies in the Northern Hemisphere Karachentsev (1972). At present, the details of photometric structure of disk-disk (S+S) galaxies are just beginning to be studied because of their intrinsic difficulties. We take...