Results of the new survey are reported in a set of three papers to be submitted to the Astrophysical Journal. Impey collaborated in the research with his former graduate student David Sprayberry, now at Kapteyn Laboratorium in Groningen, the Netherlands, Michael Irwin at the Royal Greenwich Observatory and Gregory Bothun at the University of Oregon. The astronomers scanned plates taken with the UK Schmidt Telescope at Siding Spring, Australia, with the automated plate measuring machine in Cambridge. They found more than 600 previously uncataloged galaxies in a strip of sky centered on the equator. The new galaxies are at typical distances of 200 million to 400 million light years from the Earth, Impey said.
Astronomers count the galaxies that are most easy to see.
It's as simple as that. The big bang theory predicts the existence of two to three times as much matter as is observed in the sum of all galaxies in existing catalogues. Recent surveys indicate that black holes or brown dwarfs are unlikely to contribute a significant amount of mass. However, much of the shortfall can be made up of copious numbers of dim galaxies, Impey said. The team estimates that there are between 30 percent and 100 percent more galaxies in a volume of space than astronomers previously thought, but the amount of unseen mass they represent could be even larger as these low surface brightness galaxies appear to have substantial amounts of dark matter associated with them.