The formation of ultra-compact and ultra-diffuse galaxies in clusters

Abstract

Gravitational dynamical processes are essential for the formation and evolution of structures in the universe. When we have an object inserted into a given environment, several processes will act differently in determining their dynamical history. Here, we will focus on tidal forces and dynamical friction. The former will be responsible for mass loss and, in more extreme cases, will lead to the complete disrupt of the object within the gravitational potential. The dynamical friction acts by decelerating an object, making it spiral towards the central region of the host system. This may lead to galactic cannibalism or mergers. These dynamical processes contribute, for example, to the formation of cD galaxies, stellar streams and the intra-cluster light. Recent observations and numerical simulations suggest that tidal effects and dynamical friction may play an important role in the formation of Ultra-Compact Dwarfs (UCDs) and Ultra-Diffuse Galaxies (UDGs) in groups and clusters. The main goal of this research project, which is part of the student doctoral thesis, is to study quantitatively how tidal forces and dynamical friction will impact the evolution of falling galaxies in clusters, which may lead to the formation of UCDs or UDGs. This will be done by comparing N-body simulations with a theoretical description of tidal forces and dynamical friction. We will use both tailor-made simulations (where we can control the initial conditions) and publicly available cosmological simulations. (AU)