A successful theory has to explain the extremes. We see these galaxies as they existed billions of years ago. The amount of matter connected with quasars and galaxies at such distances and distant times in the past is probably not be the same as we would measure in the local universe today, so it's very important to find out how much mass we are actually looking at in the supercluster. The first step is to look for signs of extra galaxies in the area, and now we have evidence for a surplus of galaxies. This research will be presented January 8 during the winter meeting of the American Astronomical Society in San Diego, California, and is being prepared for submission to the Astrophysical Journal.
Quasars are galaxies with bright cores, probably powered by giant black holes.
Some quasars shine with the light of a trillion Suns, and astronomers use them as cosmic beacons to probe the remotest reaches of the universe. This large quasar group holds 18 quasars in a swath of space roughly a half billion light years across. Normally, only about two to three quasars would be expected in a region this size if there were no galaxy cluster present. Those galaxies themselves are faint and have not yet been directly seen. However, magnesium atoms in the halo gas of the galaxies absorb light coming from quasars behind the cluster.