Group or Cluster Detection Algorithms

• This topic has become more and more important for the study of galaxy-halo connection.

Based on clustering of galaxies

• sfof - Friends-of-Friends Galaxy Cluster Detection Algorithm
  • By Samuel Farrens. SFoF is a friends-of-friends galaxy cluster detection algorithm that operates in either spectroscopic or photometric redshift space. The linking parameters, both transverse and along the line-of-sight, change as a function of redshift to account for selection effects.

Using the velocity (redshift information)

• [FOG - identifies locations of clusters by looking for the Finger-of-God effect]
  • Also in Abdullah et al. 2018 (AWK18) introduced a new technique (GalWeight) to assign cluster membership.
  • A catalog of 1870 clusters at 0.01 < z < 0.2 from SDSS DR13 (GalWCat19) can be found here

Based on red-sequence of the cluster members

redMaPPer: red-sequence Matched-filter Probabilistic Percolation

• redMaPPer - The Red-sequence Cluster Finder
  • By Eli Rykoff. This is the open-source, python version of the red-sequence matched-filter Probabilistic Percolation (redMaPPer) cluster finder, originally described in Rykoff et al. (2014), with updates described in Rozo et al. (2015) and Rykoff et al. (2016).
  • One of the most commonly used algorithm in recent years.

Papers:

• redMaPPer. I. Algorithm and SDSS DR8 Catalog
• redMaPPer II: X-Ray and SZ Performance Benchmarks for the SDSS Catalog
• redMaPPer - III. A detailed comparison of the Planck 2013 and SDSS DR8 redMaPPer cluster catalogues
• redMaPPer - IV. Photometric membership identification of red cluster galaxies with 1 per cent precision

Calibration:

Issues:

CAMIRA

Test cluster finder in mock catalog

• pycymatch
  • Pycymatch is a cylindrical matching code for identifying matches between a catalogue of simulated dark matter haloes populated with galaxies and the results of a cluster detection algorithm run on said catalogue.