Loose groups of galaxies in the las campanas redshift survey

Douglas L. Tucker*, Augustus Oemler, Yasuhiro Hashimoto, Stephen A. Shectman, Robert P. Kirshner, Lin Huan, Stephen D. Landy, Paul L. Schechter, Sahar S. Allam

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

82 Citations (Scopus)


A "friends-of-friends" percolation algorithm has been used to extract a catalog of δn/n = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalog contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample that either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55″ "orphan" (a galaxy with a mock redshift that was excluded from the original LCRS redshift catalog due to its proximity to another galaxy - i.e., within 55″). Median properties derived from the clean sample include a line-of-sight velocity dispersion σlos = 164 km s-1, crossing time tcr = 0.10 H-10, harmonic radius Rh = 0.58 h-1 Mpc, pairwise separation Rp = 0.64 h-1 Mpc, virial mass Mvir = 1.90 × 1013 h-1 M, total group R-band luminosity Ltot = 1.30 × 1011 h-2L, and R-band mass-to-light ratio M/L = 171 h M/L; the median number of observed members in a group is three.

Original languageEnglish
Pages (from-to)237-265
Number of pages29
JournalAstrophysical Journal, Supplement Series
Issue number2
Publication statusPublished - 2000 Oct
Externally publishedYes


  • Catalogs
  • Galaxies: Clusters: General
  • Galaxies: Distances and redshifts
  • Large-scale structure of universe
  • Surveys on-line material: Machine-readable tables

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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