Galaxies Dark and Distant
On June 19 this blog reported on discovery of a Dark Galaxy. In addition to hosting the Carnival of Space, Dr. Pamela Gay has just written about Finding Dark Galaxies. In the 1930's Fritz Zwicky suspected that unseen "dark matter" dominated galaxy clusters. Vera Rubin in the 1970's deduced its existence in galaxies from their rotation curves. Now we know that an unknown number of galaxies are completely made of the stuff.
Since DM emits no light and can be located only through gravity, we should consider Black Holes. Since every galaxy ever examined contains a Black Hole, it would be safe to surmise that dark galaxies contain them too. The dark halo surrounding a galaxy could contain billions of Black Holes. The "voids" in Space could hold billions of dark galaxies. The 71.62% of the Universe ascribed to "dark energy" could be hidden in these voids.
Atop Mauna Kea, the ultraviolet telescopes are grouped together in "Millimeter Valley." Using the UV spectrum, astronomers have discovered extremely bright young galaxies in the process of forming stars. 12 billion light-years away, we see them as they were when the Universe was less than 2 billion years old. They are the most luminous and massive galaxies ever seen at that distance.
The AzTEC submillimeter camera first detected a very bright ultraviolet source (left). Next the Smithsonian Submillimeter Array localised the source (centre). The Hubble Space Telescope database found this tiny point of light at the edge of detectability (right). This shows that the source is very bright but extremely distant, nearly hidden by dust. A bright ultraviolet signature indicates that the galaxies are in the midst of star formation, producing new suns at a rate 1000 times faster than our galaxy.
Astronomers have no idea how large galaxies could form so soon after the Big Bang. One way to form them would be around massive Primordial Black Holes. PBH's were formed from quantum fluctuations shortly after the Big Bang. Previously it was thought they would be tiny because of a finite speed of light. Discovery of massive dark galaxies is one more sign of a "c change" in physics.