VELOCIraptor is a C++ halo finder using MPI and OpenMP APIs. The repository also contains several associated analysis tools in python, example configuration files and analysis python scripts (and sample jupyter notebooks). The code can also be compiled as a library for on-the-fly halo finding within an N-body/hydrodynamnical code. Currently integration is limited to SWIFTSIM but extensions are in the works for other codes.

There is an associated halo merger tree code TreeFrog (also C++ MPI+OpenMP).

If you are using VELOCIraptor please cite the following paper, which describe the code in full:

  author = {{Elahi}, Pascal J. and {Ca{\~n}as}, Rodrigo and {Poulton}, Rhys J.~J. and {Tobar}, Rodrigo J. and {Willis}, James S. and {Lagos}, Claudia del P. and {Power}, Chris and {Robotham}, Aaron S.~G.},
  title = {Hunting for galaxies and halos in simulations with VELOCIraptor},
  journal = {\pasa},
  keywords = {dark matter, galaxies: evolution, galaxies: halos, methods: numerical, Astrophysics -Cosmology and Nongalactic Astrophysics},
  year = {2019},
  month = {Jan},
  volume = {36},
  eid = {e021},
  pages = {e021},
  doi = {10.1017/pasa.2019.12},
  archivePrefix = {arXiv},
  eprint = {1902.01010},
  adsurl = {},

If using VELOCIraptor for galaxy finding, please also cite:

  author = {{Ca{\~n}as}, Rodrigo and {Elahi}, Pascal J. and {Welker}, Charlotte and {del P Lagos}, Claudia and {Power}, Chris and {Dubois}, Yohan and {Pichon}, Christophe},
  title = {Introducing a new, robust galaxy-finder algorithm for simulations},
  journal = {\mnras},
  keywords = {methods: numerical, galaxies: evolution, dark matter, cosmology: theory, Astrophysics - Astrophysics of Galaxies},
  year = {2019},
  month = {Jan},
  volume = {482},
  number = {2},
  pages = {2039-2064},
  doi = {10.1093/mnras/sty2725},
  archivePrefix = {arXiv},
  eprint = {1806.11417},
  primaryClass = {astro-ph.GA},
  adsurl = {},

The original idea, which also discusses the identification of tidal debris is in:

  author = {{Elahi}, Pascal J. and {Thacker}, Robert J. and {Widrow}, Lawrence M.},
  title = {Peaks above the Maxwellian Sea: a new approach to finding substructures in N-body haloes},
  journal = {\mnras},
  keywords = {methods: data analysis, methods: numerical, galaxies: haloes, galaxies: structure, dark matter, Astrophysics - Cosmology and Extragalactic Astrophysics},
  year = {2011},
  month = {Nov},
  volume = {418},
  number = {1},
  pages = {320-335},
  doi = {10.1111/j.1365-2966.2011.19485.x},
  archivePrefix = {arXiv},
  eprint = {1107.4289},
  primaryClass = {astro-ph.CO},
  adsurl = {},

An online entry can also be found at NASA’s ADS service.