Credit: R. G. Clowes / UCLan
Thanks to John Merryman for suggesting the topic of this post. Earlier this month, a team of astronomers led by Roger G. Clowes at the University of Central Lancashire reported the discovery of the largest structure seen in the universe, a clump of 73 quasars spanning 4 billion light years across, in data taken by the Sloan Digital Sky Survey. (Our Milky Way, is about 100,000 light years across for comparison). The results were published in MNRAS.
The cluster has been dubbed the "Huge-LQG" (Huge-large-quasar-group), and neighbors another large clump, the "CCLQG" (where the CC stands for the names of its discoverers, Clowes (again) and Campusano). This corner of the sky is apparently where all fashionable quasars want to hang out, and that's a problem for modern cosmology, which is founded on the "cosmological principle" that
the universe should look pretty much the same in every direction, on large scales.
The image shows the occurrence of quasars (darker colors indicate more quasars) in the region. The HUGE-LQG is marked by the chain of black circles, while the red crosses mark its smaller neighbor. The map covers an impressive 29.4 by 24 degrees on the sky. (Credit: R. G. Clowes / UCLan.)
The story has been reported a lot in the news, and you can listen to a nice NPR podcast about it here. Taken alone, it's a nice story about a puzzling thing that seems to defy our current theories of cosmology. But there's a wider question: Cosmology is a relatively new science (there'll be a bit more about that in this month's forthcoming podcast, which I am about to upload). Cosmologists and astronomers don't have the luxury of being able to carry out experiments to test their theories and so models are built based on the relatively small amount of data available at the time. So should we be surprised that as we push the observational boundaries, the data calls our models into question? Or do you think that each apparently startling result will eventually be brought into the fold?
Please feel free to add in other links to recent results that have been puzzling astronomers and cosmologists and to discuss what they ultimately mean for our standard model of cosmology.