Saturday, January 12, 2013
Largest Spiral Galaxy Discovered
Astonomers have discoverd the largest lnown structure in the universe. clump of active galactic core that stretches four billion light-years from end to end. The structure is a large quasar group (LQG), a collection of extemely luminous galactic nuclei powered by supermassive central black holes. This particular group is so large that it challenges modern cosmological theort, researchers said. "While it is difficult to fathom the scale of this LQG, we can say quite definetely it is the largst structure even seen in the entire universe", the lead author Roger Glowes, of the Central University of Lankshire in England, said in a statement. "This is a hugely exciting not least because it runs counter to our understanding of the scale of the universe". Quasars are the brightest objects in the universe, For decades, astronomers have known that they tend to assemble in huge groups, some of which are 600 milion light years wide. But the record-breaking quasar group, which Glowes and his team spotted in data gathered by Sloan Digital Sky Survey, is on another scale altogether. The newly found LQG is composed of 73 quasars and spans about 1.6 billion light-years in most of the directions, though it is 4 billion light-years across at its widest point. To put that mind- boggling size into perspective, the disk of Milky-Way galaxy, home of Earth's solar system- is about 100,000 light-years wide. The Milky-Way is separated from its nearest neighbour, Andromeda, by about 2.5 million light-years. The newly discovered LQC is so enormous that theory predicts it should not exist, researchers said. The quasar group appears to violate a widely accepted asssumption known as cosmological principle, which holds that universe is essentialy homogenous when viewed at a sufficiently large scale. Researcher say that a structure larger than about 2.5 light-years should not exist.