This gaseous blob is the center of a galaxy cluster.
Lab-1 Image: J.Geach/D.Narayanan/R.Crain
There's an enormous, glowing, colorful blob in space that has perplexed scientists for years. Until now.
The SSA22-Lyman-alpha blob 1, or LAB-1, is part of a class of cold hydrogen gas accumulations called Lyman-alpha blobs. LABs, as they're called for short, extend across hundreds of thousands of light years toward distant regions of the universe. They're named after Lyman-alpha radiation, the specific frequency of ultraviolet light they emit. The findings about LAB-1 were recently accepted for publishing in the Astrophysical Journal.
LAB-1 is one of the largest blobs ever discovered, initially spotted in 2000. It's at the center of a large protocluster, a dense region of the universe, according to Jim Geach, an astronomer at the University of Hertfordshire. "This region will eventually collapse into a large cluster. So the fact that we see this large blob close to the center suggests it has something to do with the formation of large galaxies," he told Gizmodo.
The blob emits several clumps of wavelength radiation that correspond to different galaxies. The emissions come from two central galaxies that are about to converge. Meanwhile, the smaller galaxies have gathered around them. "We're basically seeing the formation of the center of a cluster of galaxies, right when all the action is taking place," Geach told Gizmodo.
To uncover the blob's source of light, researchers used a simulation of galaxy evolution called Feedback in Realistic Environments. It showed that hydrogen gas would absorb light from new stars and emit it as Lyman-alpha radiation.
LAB-1 is 11.5 billion light years away—so the way astronomers are observing it now, via a radio telescope called Atacama Large Millimeter/submillimeter Array (ALMA), is the way the blob was 11.5 billion years ago. And because the blob is so far away both in time and space, the radiation shifted toward longer wavelengths of spectral light emissions, so that it looks like well, just a blob of color to astronomers down on Earth.
The findings about LAB-1 could offer insight into how structures in the universe are formed. The 15-year-old mystery of the blob has finally been solved, he told UPI. And he told Motherboard that the findings suggest that all of these blobs are formed in the same way.
"Lyman-alpha blob 1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster," he told me. "This is a region that is key for galaxy formation, but is very poorly explored. With LABs, nature seems to have given us the tantalising snapshot of what's going on."
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