The hierarchical structure of galactic haloes: Classification and characterization with halo-optics

William H. Oliver, Pascal J. Elahi, Geraint F. Lewis, Chris Power

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
31 Downloads (Pure)


We build upon Ordering Points To Identify the Clustering Structure (optics), a hierarchical clustering algorithm well known to be a robust data miner, in order to produce halo-optics, an algorithm designed for the automatic detection and extraction of all meaningful clusters between any two arbitrary sizes. We then apply halo-optics to the 3D spatial positions of halo particles within four separate synthetic Milky Way-type galaxies, classifying the stellar and dark matter structural hierarchies. Through visualization of the halo-optics output, we compare its structure identification to the state-of-the-art galaxy/(sub)halo finder VELOCIraptor, finding excellent agreement even though halo-optics does not consider kinematic information in this current implementation. We conclude that halo-optics is a robust hierarchical halo finder, although its determination of lower spatial-density features such as the tails of streams could be improved with the inclusion of extra localized information such as particle kinematics and stellar metallicity into its distance metric.

Original languageEnglish
Pages (from-to)4420-4437
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 1 Mar 2021


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