DISTANT CLUSTERS

A simulated view of a field in the core of the Coma cluster as it would be seen in a deep HST exposure of the type shown below. The simulated cluster is at z=0.4 and has been observed for ~8 orbits in F814W. The image on the left is the original F606W single orbit of Coma taken by John Lucey, that on the right shows this shifted and degraded to represent the z=0.4 view. The bottom frame shows a 75×75 arcsec region from the simulated z=0.4 cluster after adding in foreground field contamination. While the luminous cluster ellipticals are still easily visible a very large fraction of the cluster population has disappeared or become unrecognizable due to a combination of dimming and and lower angular resolution. The latter appears to be particularly important when dealing with populations which were originally very compact anyway (e.g. lower luminosity ellipticals).

A 150×150 arcsec (1.1 Mpc square for H=50km/s/Mpc) region of the HST/WFPC2 image of the distant rich cluster Cl0054-27 (z=0.56) from the Morphs sample. The cluster is seen as it was roughly 6 billion years ago. The image is a `real' color representation of the field made by combining images in Blue and Red filters. Note the massive red galaxies which dominate the very central regions of the cluster and the large population of blue disturbed galaxies on the outskirts. In addition you can see a number of faint blue objects in the very center of the cluster, these are likely to be images of background galaxies which are being gravitationally magnified by the mass in the foreground cluster. These are large, full scale GIF images which may be more easily viewed if they are downloaded and then manipulated with XV.

A `harassed' galaxy in the cluster, this is a 20×20 arcsec (150kpc) section of the above frame showing the faint 100-kpc long tidal streams emanating from the galaxy.

The full frame HST/WFPC2 image of the distant rich cluster Cl0016+16 (z=0.55) from the Morphs sample, corresponding to 1.1 Mpc across at the cluster for H=50km/s/Mpc. The cluster galaxies are viewed as they were roughly 6 billion years ago. The image is a `real' color representation of the field made by combining images in Blue and Red filters. Note the massive red galaxies which dominate the very central regions of the cluster (bottom-left) and the large population of blue disturbed and interacting galaxies on the outskirts.

The distant cluster Cl0412-65 (z=0.51) from the Morphs sample shown as a `true' color image from the HST/WFPC2 F555W/F814W exposures. Again the field of view corresponds to 1.1 Mpc at the cluster redshift for H=50km/s/Mpc. Note the low surface brightness galaxies seen in the central regions of the cluster. The redshift of these features are of particular interest to understanding the evolution of the cluster population and the role of dynamical processes in changing the morphologies of cluster galaxies over the last 6 Gyrs.

HST/WFPC2 `real' color images of confirmed members in three z=0.55 clusters. These are 6×6 mosaics objects from the Morphs samples. The individual subimages are each 7 arcsec across (70 pixels square = 52 kpc at the cluster distance using H=50km/s/Mpc). The two images have different stretches.

  • Higher contrast stretch

    HST/WFPC2 images of confirmed members of z=0.4 clusters. These are 5×5 mosaics of emission line objects from the Morphs samples. The individual subimages are each 5 arcsec (50 pixels square = 32 kpc at the cluster distance using H=50km/s/Mpc).

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    Last Modified: April 25th, 1997. [Netscape 2.0]