Related papers: Enhanced interactions, mergers and starbursts in d…
Star complexes are the highest level groupings in the hierarchy of the embedded young stars, clusters and associations, which obey the size - age relation. Starburst clumps, superassociations, supergiant HII regions are different titles for…
Young star clusters in interacting galaxies are often found in groups or clusters of star clusters containing up to 100 single clusters. In our project we study the future fate of these clusters of star clusters. We find that the star…
Disk galaxies at high redshift (z~2) are characterized by high fractions of cold gas, strong turbulence, and giant star-forming clumps. Major mergers of disk galaxies at high redshift should then generally involve such turbulent clumpy…
Clusters of galaxies are merging during the formation of large-scale structures in the Universe. Based on optical survey data, we identify a large sample of pre-mergers of galaxy clusters and merging subclusters in rich clusters. We find…
Most giant spiral galaxies have pseudo or disk-like bulges that are considered to be the result of purely secular processes. This may challenge the hierarchical scenario predicting about one major merger per massive galaxy ($>$$3\times…
Shell galaxies make a class of tidally distorted galaxies, characterised by wide concentric arc(s), extending out to large galactocentric distances with sharp outer edges. Recent observations of young massive star clusters in the prominent…
We study the formation and the evolution of galaxy groups in a critical universe, showing the importance of secondary infall for their dynamical evolution. Merging is only slightly accelerated if galaxies have massive halos, because the…
We use extensive new observations of the very rich z ~ 0.4 cluster of galaxies A851 to examine the nature and origin of starburst galaxies in intermediate-redshift clusters. New HST observations, Spitzer photometry and ground-based…
An ensemble cluster has been formed from a data set comprising a complete magnitude-limited sample of 680 giant galaxies (M(B) < -19) in 8 low-redshift clusters, normalised by the velocity dispersions and virial radii for the early-type…
The observed morphological evolution since z ~ 0.5 within galaxy clusters provides evidence for a hierarchical universe. This evolution is driven by dynamical effects that operate within the cluster environment -- suppression of…
We study the effect of mergers on the morphology of galaxies by means of the simulated merger tree approach first proposed by Moster et al. This method combines N-body cosmological simulations and semi-analytic techniques to extract…
The strongest starbursts are observed towards galaxy nuclei, or circumnuclear regions. However in interacting galaxies, star formation is also triggered in overlap regions far from nuclei, in spiral arms and sometimes in tidal tails. What…
Interacting galaxies favor the formation of star clusters but are also suspected to affect their evolution through an intense and rapidly varying tidal field. Treating this complex behaviour remains out-of-reach of (semi-)analytical…
Galaxy evolution is in transition from an early universe dominated by hierarchical clustering to a future dominated by secular processes. These result from interactions involving collective phenomena such as bars, oval disks, spiral…
Merging of galaxy clusters are some of the most energetic events in the Universe, and they provide a unique environment to study galaxy evolution. We use a sample of 84 merging and relaxed SPT galaxy clusters candidates, observed with the…
An overview of our current understanding of the formation and evolution of star clusters is given, with main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within…
Clusters are the dense inner regions of a wide-spread hierarchy of young stellar structures. They often reveal a continuation of this hierarchy inside of them, to smaller scales, when they are young, but orbital mixing eventually erases…
Galaxy evolution depends strongly on the environment. Dynamical interactions and subsequent evolution make galaxies more concentrated, with higher surface densities, and also trigger star-formation, which consumes the available cold gas.…
Theoretical considerations and observational data support the idea that mergers were more frequent in the past. At redshifts z = 2 to 5, violent interactions and mergers may be implicated by observations of Lyman-break galaxies, sub-mm…
Close encounters and physical collisions between stars in young dense clusters may lead to the formation of very massive stars and black holes via runaway merging. We examine critically some details of this process, using N-body simulations…