Butcher & Oemler cluster A 2111: A head-on merger at z = 0.23

Q. Daniel Wang*, Melville P. Ulmer, Russell J. Lavery

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We present ROSAT PSPC and HRI observations of A 2111, the richest galaxy cluster photometrically surveyed by Butcher & Oemler. The cluster contains a distinct comet-shaped X-ray subcomponent that appears hotter than the rest of the cluster. The galaxy and X-ray surface brightness distributions of the cluster show a similarly elongated morphology. These results suggest that the cluster is undergoing a head-on subcluster merger. This merger may also be responsible for the high fraction of gas-rich blue galaxies observed in the cluster. We have further detected a poor cluster along the merging axis and at a projected distance of ∼ 5 Mpc from A2111.

Original languageEnglish (US)
Pages (from-to)702-714
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 1997


  • Cosmology: observations
  • Galaxies: clusters: individual: A 2111
  • Galaxies: evolution
  • Large-scale structure of Universe
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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