We can get a better handle on the look & feel of accretion events like this in this Illustris sim:
http://www.illustris-project.org/mov..._adiabatic.mp4
The sim starts at z=10, roughly 600 million years after the BB. The left panel shows the timeline evolution of adiabatic heating (density variations at constant temperature) and the right side shows the combined effects of gas cooling, primordial star formation, and AGN or active galactic nuclei. AGNs mix newly formed and chemically enriched gas with the older primordial gas, thus seeding the universe with the complex elements that eventually build up into structures like us. The words "gas cooling" above may seem odd given that what we see in this sim reflects the effects of enormous system-wide heating via star formation. However, in order for gas to get dense enough for stars to form, the gas has to cool down from its primordial extreme kinetic activity (kinetic energy is considered "heat") of millions of degrees K. The only way it can do that is by radiating away the energy excess into space as space itself expands. The whole process begins slowly but by the midpoint of the sim you can see what messy places galaxies can be as they eat each other alive.
If you Google phrases like "simulations of galaxy formation" you will be astonished at the number of accurate visualizations which the professional astronomy community creates to show us visually what they know mathematically.
=Dana in S Africa