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

Research output: Contribution to journalReview articlepeer-review

78 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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