Observations of high redshift type Ia supernovae (SNe) will enable us to probe the structure of galaxy halos and the composition of dark matter. The future prospects for this field are briefly discussed here. First the ability of SN observations to differentiate between dark matter made of macroscopic compact objects and dark matter made of microscopic particles is reviewed. Then a new method f...

Using large-scale hydrodynamic simulations with heuristic criteria for galaxy formation, we investigate how the galaxy field is related to physical parameters, such as the mass density and the gas temperature. We find that the relation between the galaxy and mass density fields is a function of scale. The bias b(R) ≡ σg(R)/σ(R), where σg(R) is the variance of galaxy counts in spheres of radius ...

We study the stellar mass assembly of the Spiderweb Galaxy (MRC 1138-262), a massive z = 2.2 radio galaxy in a protocluster and the probable progenitor of a brightest cluster galaxy. Nearby protocluster galaxies are identified and their properties are determined by fitting stellar population models to their rest-frame ultraviolet to optical spectral energy distributions. We find that within 150...

Growing evidence has been accumulated for that some gas-rich dwarf galaxies are formed from material liberated by galaxy collisions and/or mergers. Also, gas-poor dwarf elliptical galaxies are often found in the central regions of clusters of galaxies. These observations suggest strongly that the formation of most dwarf galaxies is linked to galaxy interactions. Therefore, now seems like the ri...

A synopsis of the recent results from our study of galaxygalaxy lensing in clusters is presented. We have applied our analysis techniques to the sample of HST cluster-lenses that span a redshift range from z = 0.18–0.58. We find that there is evidence that the total mass of a typical early-type cluster L galaxy increases with redshift. For the lowest redshift bin, a sensible comparison can be m...