We applied computational tools for automatic detection of peculiar galaxy pairs. We first detected in SDSS DR7 ∼400,000 galaxy images with i magnitude <18 that had more than one point spread function, and then applied a machine learning algorithm that detected ∼26,000 galaxy images that had morphology similar to the morphology of galaxy mergers. That dataset was mined using a novelty detection ...

The SDSS galaxy catalog is one of the best databases for galaxy distribution studies. The SDSS DR8 data is used to construct the galaxy cluster catalog. We construct the clusters from the calculated luminosity density field and identify denser regions. Around these peak regions we construct galaxy clusters. Another interesting question in cosmology is how observable galaxy structures are connec...

We note that galaxy-galaxy lensing by non-spherical galaxy halos produces a net anti-correlation between the shear of background galaxies and the ellipticity of foreground galaxies. This anti-correlation would contaminate the tomographic cosmological weak lensing two point function if the effect were not taken into account. We compare the size of the galaxy-galaxy lensing contribution to the ch...

The CNOC2 Field Galaxy Redshift Survey presently contains some 5000 galaxy redshifts, plus extensive UBgRI photometry, and is the largest galaxy sample at moderate redshifts 0.1 < z < 0.6. Here we present some preliminary results on the galaxy luminosity function (LF) and its redshift evolution, using a sample of R < 21.5 CNOC2 galaxies, subdivided into early, intermediate, and late types based...

We present evidence for a Spitzer-selected luminous infrared galaxy (LIRG) behind the Bullet Cluster (1E0657-56). The galaxy, originally identified in IRAC photometry as a multiply imaged source, has a spectral energy distribution consistent with a highly extincted (AV ∼ 3.3), strongly star-forming galaxy at z ∼ 2.7. Our strong gravitational lensing analysis of the cluster indicates that the ma...

We explore the distribution of mass about the expected sites of galaxy formation in a high-resolution hydrodynamical simulation of a ΛCDM cosmology which includes cooling, star-formation and feedback. We show that the evolution of the galaxy bias is non-trivial and non-monotonic and that the bias is stochastic. We discuss the galaxy-mass cross-correlation function and highlight problems with th...

We present the results of our HI survey of six loose groups of galaxies analogous to the Local Group. The survey was conducted using the Parkes telescope and the Australia Telescope Compact Array to produce a census of all the gas-rich galaxies and analogs to the high-velocity clouds (HVCs) within these groups down to MHI< 10 M⊙ as a test of models of galaxy formation. We present the HI mass fu...

Gravitational light deflection due to mass along the line-of-sight will distort the images of background sources. This effect has been used successfully to investigate the mass distribution of galaxy clusters. Although an individual galaxy is not massive enough to cause a detectable lensing distortion in the background population, this effect can be measured statistically for a population of ga...

We present the results of a study of galaxy activity in two merging binary clusters (A168 and A1750) using the Sloan Digital Sky Survey (SDSS) data supplemented with the data in the literature. We have investigated the merger histories of A168 and A1750 by combining the results from a two-body dynamical model and X-ray data. In A168 two subclusters appear to have passed each other and to be com...