Related papers: Tides, Interactions, and Fine-Scale Substructures …
How does the tidal debris of minor galaxy mergers contribute to structures in spiral galaxies or in the intergalactic medium? While major mergers are known to create structures such as tidal dwarf galaxies and star clusters within their…
We study a sample of 19 galaxy clusters in the redshift range $0.15<z<0.30$ with highly complete spectroscopic membership catalogues (to $K < K^{\ast}(\rm z)+1.5$) from the Arizona Cluster Redshift Survey (ACReS); individual weak-lensing…
High-redshift clusters of galaxies show an over-abundance of spirals by a factor of 2-3, and the corresponding under-abundance of S0 galaxies, relative to the nearby clusters. This morphological evolution can be explained by tidal…
Deep images of the Centaurus and Coma clusters reveal two spectacular arcs of diffuse light that stretch for over 100 kpc, yet are just a few kpc wide. At a surface brightness of m_b \sim 27-28th arcsec^-2, the Centaurus arc is the most…
We present new results of a program to study the detailed morphologies of galaxies in intermediate redshift clusters and hence understand the physical origin of the enhanced star formation in these environments at earlier epochs. Deep, high…
We present new deep photometry of the rich globular cluster (GC) systems around the Brightest Cluster Galaxies UGC 9799 (Abell 2052) and UGC 10143 (Abell 2147), obtained with the HST ACS and WFC3 cameras. For comparison, we also present new…
We have observed three fields of the Coma cluster of galaxies with a narrow band (modified Stromgren) filter system. Observed galaxies include 31 in the vicinity of NGC 4889, 48 near NGC 4874, and 60 near NGC 4839 complete to M_5500=-18 in…
We compare V-band structural properties of cluster and field galaxies, to test whether much of the current cluster membership resulted from the transformation of infalling spirals into red early types. We use 140 galaxies from 3 z<0.6 Abell…
We present a study of galaxy mergers and the influence of environment in the Abell 901/902 supercluster at z~0.165. We use HST ACS F606W data from the STAGES survey, COMBO-17, Spitzer 24um, and XMM-Newton X-ray data. Our analysis utilizes…
Galaxy groups and clusters are the most massive collapsed structures in the Universe. Those structures are formed by collapsing with other smaller structures. Groups and cluster mergers provide an appropriate environment for the evolution…
The hierarchical mergers that form the haloes of dark matter surrounding galaxies, groups and clusters are not entirely efficient, leaving substantial amounts of dense substructure, in the form of stripped halo cores or `subhaloes',…
We investigate how the environment of a dynamically unrelaxed galaxy cluster influences the structure and dynamics of stellar bars. In particular, we examine cluster-centric variations in normalised bar size and bar pattern speed in Abell…
I analyse the projected density distribution of member stars over a wide area surrounding 18 Galactic globular clusters using the photometric and astrometric information provided by the second data release of the Gaia mission. A 5D mixture…
Minor mergers are thought to be important for the build-up and structural evolution of massive elliptical galaxies. In this work, we report the discovery of a system of four shell features in NGC 4889, one of the brightest members of the…
Clusters of galaxies are believed to be at the intersections of cosmological filaments and to grow by accreting matter from these filaments. Such continuous infall has major consequences not only on clusters but also on the physics of…
We present a high-resolution simulation of globular cluster formation in a galaxy merger. For the first time in such a simulation, individual star clusters are directly identified and followed on their orbits. We quantitatively compare star…
We present an end-to-end, two-phase model for the origin of globular clusters (GCs). In the model, populations of stellar clusters form in the high-pressure discs of high-redshift ($z>2$) galaxies (a rapid-disruption phase due to tidal…
Structure formation is thought to act via hierarchical mergers and accretion of smaller systems driven by gravity with dark matter dominating the gravitational field. Combining X-ray and optical imaging and spectroscopy provides a powerful…
The ~800 optically unseen (R>25.5) 24mum-selected sources in the complete Spitzer First Look Survey sample (Fadda et al. 2006) with F[24mum]>0.35 mJy are found to be very strongly clustered. If, as indicated by several lines of…
We study the presence of tidal features associated with ultra diffuse galaxies (UDGs) in galaxy clusters. Specifically, we stack deep Subaru images of UDGs in the Coma cluster to determine whether they show position angle twists at large…