A Sloan Digital Sky Survey (SDSS) source sample containing 44,200 quasar redshifts is examined. Although arguments have been put forth to explain some of the structure observed in the redshift distribution, it is argued here that this structure may just as easily be explained by the presence of previously predicted preferred redshifts. Subject headings: galaxies: active galaxies: distances and ...

The distribution in color and absolute magnitude is presented for 55,158 galaxies taken from the Sloan Digital Sky Survey in the redshift range 0.08 < z < 0.12, as a function of galaxy number overdensity in a line-of-sight cylinder of transverse radius 1 h−1 Mpc. In all environments, bulge-dominated galaxies (defined to be those with radial profiles best fit with large Sérsic indices) form a na...

We have measured the central stellar velocity dispersion in the host galaxies of 11 BL Lac objects with redshifts z ≤ 0.125. The range of velocity dispersions, ∼ 170 − 370 km s−1, is similar to that of nearby radio galaxies. Using the correlation between stellar velocity dispersion and black hole mass defined for nearby galaxies, we derive estimates of the black hole masses in the range 107.9 −...

We present a model to investigate the formation and evolution of cluster galaxies using cosmological high-resolution N -body simulations. The N -body simulations are used to construct merging history trees of dark halos. Gas cooling, star formation, supernova feedback and mergers of galaxies within dark halos are included by using simple prescriptions taken from semi-analytic models of galaxy f...

This work presents high S/N spectroscopic observations of a representative sample of nearby elliptical galaxies. These observations provide a strong test of models for the formation of elliptical galaxies and their star formation histories. Combining these data with the Gonzalez (1993) data set, a volume limited sample of 45 galaxies has been defined. Results are in agreement with previous stud...

We discovered strong gravitational lensing in 4 galaxy clusters by visual inspection of the Sloan Digital Sky Survey images in Data Release 6 (SDSS DR6). Two of them show the Einstein rings, and the other two show tangential giant arcs. These arcs or rings have large angle separations of > 8 from the bright central galaxies. The lensed images in general are bluer than cluster member galaxies. T...

The deep near–infrared luminosity function of AC118, a cluster of galaxies at z = 0.3, is presented. AC118 is a bimodal cluster, as evidenced both by our near–infrared images of lensed galaxies, by public X–ray Rosat images and by the spatial distribution of bright galaxies. Taking advantage of the extension and depth of our data, which sample an almost unexplored region in the depth vs. observ...

We compare the cosmic evolution of star formation rates in galaxies with that of their neutral hydrogen densities. We highlight the need for neutral hydrogen to be continually replenished from a reservoir of ionized gas to maintain the observed star formation rates in galaxies. Hydrodynamic simulations indicate that the replenishment may occur naturally through gas infall, although measured rat...

We present the Arecibo Dual-Beam Survey (ADBS), a “blind” 21cm survey for galaxies. The ADBS is the largest to date with the Arecibo radio telescope. We were able to achieve an rms sensitivity of 3-4 mJy in only 7 seconds. The ADBS covers substantially more volume than the Spitzak & Schneider (1998) and the Zwaan et al. (1997) surveys. It is surpassed by the Parkes HIPASS survey (Kilborn et al....