References: https://www.cfa.harvard.edu/news/middleweight-black-hole-hiding-center-giant-star-cluster https://www.nature.com/articles/nature21361 http://spiff.rit.edu/classes/phys230/lectures/clusters/clusters.html https://arxiv.org/pdf/2005.00801.pdf
In depth description and implementation of Plummer model: http://www.artcompsci.org/kali/vol/plummer/title.html#TOC
Videos on Barnes-Hut: https://www.youtube.com/watch?v=r8RC1kmdCiQ (visualization) https://www.youtube.com/watch?v=tOlKLJ4WmSE