Related papers: Compact groups from the Millennium Simulations: I.…
Studies of galaxy protoclusters yield insights into galaxy cluster formation complementary to those obtained via `archaeological' studies of present-day galaxy clusters. Submillimetre-selected galaxies (SMGs) are one class of sources used…
The Arecibo HI Strip Survey probed the halos of ~300 cataloged galaxies and the environments of ~14 groups with sensitivity to neutral hydrogen masses > 10^7 M_sun. The survey detected no objects with properties resembling the High Velocity…
Galactic conformity is the phenomenon whereby galaxy properties exhibit excess correlations across distance than that expected if these properties only depended on halo mass. We perform a comprehensive study of conformity at low redshift…
Compact groups (CGs) of galaxies are extreme environments for morphological transformations and the cessation of star formation. Though initially considered isolated, it is now recognised that many CGs are embedded in larger structures. We…
We use a matched filter algorithm to find and study clusters in both N-body simulations artificially populated with galaxies and the 2MASS survey. In addition to numerous checks of the matched filter algorithm, we present results on the…
Major mergers of disk galaxies are thought to be a substantial driver in galaxy evolution. To trace the fraction and the rate galaxies are in mergers over cosmic times, several observational techniques, including morphological selection…
We present the catalog of galaxy groups in the Local Supercluster. Our algorithm bases on assumption that a total energy of physical pair of galaxies must be negative. About 54% of the galaxies in our sample have been gathered in 1082…
In the last decade, extended stellar clusters with masses in the range from a few 10^4 to 10^8 M_sun have been found in various types of galaxies in different environments. Objects with masses comparable to normal globular clusters (GCs)…
From R-band images of 39 Hickson compact groups (HCGs), we use galaxy counts to determine a luminosity function extending to M_R=-14.0, approximately two magnitudes deeper than previous compact group luminosity functions. We find that a…
We predict the amplitude of the gravitational redshift of galaxies in galaxy clusters using an N-body simulation of a Lambda CDM universe. We examine if it might be possible to detect the gravitational effect on the total redshift observed…
A galaxy group catalog is built from the sample of the 2MASS Redshift Survey almost complete to Ks=11.75 over 91% of the sky. Constraints in the construction of the groups were provided by scaling relations determined by close examination…
Identifying galaxy groups from redshift surveys of galaxies plays an important role in connecting galaxies with the underlying dark matter distribution. Current and future high-$z$ spectroscopic surveys, usually incomplete in redshift…
We find evidence for accelerated evolution in compact group galaxies from the distribution in mid-infrared colorspace of 42 galaxies from 12 Hickson Compact Groups (HCGs) compared to the the distributions of several other samples including…
A robust prediction of $\Lambda{\rm CDM}$ cosmology is the halo circular velocity function (CVF), a dynamical cousin of the halo mass function. The correspondence between theoretical and observed CVFs is uncertain, however: cluster galaxies…
We consider here the class of compact, isolated, high-velocity HI clouds, CHVCs, which are sharply bounded in angular extent down to a limiting column density of 1.5x10^18 cm^-2. We describe our automated search algorithm and it's…
The most massive and luminous galaxies in the Universe serve as powerful probes to study the formation of structure, the assembly of mass, and cosmology. However, their detailed formation and evolution is still barely understood. Here we…
The Millennium Galaxy Catalogue (MGC) provides a structural database comprising 10,095 well resolved galaxies drawn from a 37.5 sq. deg region of sky, with $B_{\tiny \sc mgc} < 20.0$ mag and 96.1 per cent spectroscopic completeness. The…
We present a very large high-resolution cosmological N-body simulation, the Millennium-XXL or MXXL, which uses 303 billion particles to represent the formation of dark matter structures throughout a 4.1Gpc box in a LambdaCDM cosmology. We…
We present results from a systematic investigation of the X-ray properties of a sample of moderate redshift (0.3<z<0.6) galaxy groups. These groups were selected not by traditional X-ray or optical search methods, but rather by an…
We study the luminosity gap, dm12, between the first and second ranked galaxies in a sample of 59 massive galaxy clusters, using data from the Hale Telescope, HST, Chandra, and Spitzer. We find that the dm12 distribution, p(dm12), is a…