Detection of a galaxy cluster at z=2.4
Session 107 -- Galaxies: Morphology and Interactions
Display presentation, Thursday, 12, 1995, 9:20am - 6:30pm

## [107.02] Detection of a galaxy cluster at z=2.4

Bruce Woodgate (GSFC), Paul Francis (U. Melbourne), Steve Warren (Imperial College), Palle Moller (STScI), Ted Williams (Rutgers U.), James Lowenthal (Lick Obs)

We have detected a group of galaxies at z=2.38. The group lies near a triple system of damped Lyman-$\alpha$ absorption-lines in a background QSO, and is part of a large ($> 3$Mpc) cluster of damped systems (Francis \& Hewett 1993, AJ 105, 1633).

Two of the galaxies in the group were detected using Fabry-Perot narrow band imaging and broad band imaging at the CTIO 4-m telescope. Both have been spectroscopically confirmed. An additional 10 IR-bright objects cluster around these two; from their IR/optical colours most have to be galaxies at the same redshift.

The group has a diameter of $\sim 80$kpc, a velocity dispersion of $\sim 500$ km$s^{-1}$ and a mass of $\sim 10^{12}$ Solar masses; it may represent a giant elliptical galaxy in the act of formation. One galaxy in the group shows an extended tail of Lyman-$\alpha$ emission.