ytree: A Python package for analyzing merger trees
Britton Smith, Meagan Lang · The Journal of Open Source Software · 2019
The formation of cosmological structure is dominated, especially on large scales, by the force of gravity.In the early Universe, matter is distributed homogeneously, with only small fluctuations about the average density.Overdense regions undergo gravitational collapse to form bound structures, called halos, which will host galaxies within them.Halos grow via accretion of the surrounding material and by merging with other halos.This process of merging to form increasingly massive halos is naturally conceptualized as an inverted tree, where small branches connect up to continually larger ones, leading eventually to a trunk.