A Disk-Disk Major Merger Event in a

Cosmological Hydrodynamical Zoom-Simulation

by David Schlachtberger

A Disk-Disk Major Merger Event in a Cosmological Hydrodynamical Zoom-Simulation

The idea of the hierarchical growth of structures has shaped our understanding of the formation of galaxies in the universe for many years, but due to numerical complexity a detailed study of the evolution of those galaxies from high redshift to present day has been a challenge so far. With larger computational powers and improved numerical methods available that include detailed baryonic physics, the goal of understanding the formation of the large variety of galaxies at the present day and their connections with each other has come into reach. With the aim to understand the formation of galaxies and especially the impact of the gas component and the feedback on the evolution of elliptical galaxies, we performed high-resolution zoom simulations of galaxies selected from a large cosmological box (Gpc in size), which are forming at the border or inside a void structure at present day. The movie presented in this highlight shows, within a self consistent cosmological context, the formation of a disk galaxy from a redshift of z=10 to z=0.45, where it suffers a major merging event with another massive disk galaxy. This causes a starburst and changes the morphology of the two galaxies that then form a single spheroidal galaxy. This is an event that can be seen in the present day universe, for example in the famous Mice Galaxies or the Antennae Galaxies. Our spheroidal galaxy undergoes another dynamical event during the last 2 Gyrs of its life until the present day that is also a major component of galaxy evolution: a massive dry minor merger. This merger leaves shell-like structures around the galaxy as a signature that is visible for about 200-500 Myrs, a phenomenon that can be observed at present day, for example in the Arp 227 Galaxy.
This galaxy is part of the work of the Magneticum Team at the CAST Group of the University observatory in Munich. Feel free to use this Movie for educational purposes. Computations where performed within the SuperCAST project on SuperMUC, located at the LRZ.
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The corresponding animations can be found here:

high resolution movie
low resolution movie