In particular, the extended Lyman-alpha glow provides information on what is happening in the primordial gas clouds surrounding young galaxies, a region that is very hard to study, but critical to understand.
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Scientists believe some of the universe’s most massive galaxies form in LABs and each discovery brings us closer to understanding how and why that happens. The incredible pictures are of a hydrogen based gas formation source, often times referred to as the Lyman-alpha Blobs (LABs). The name reflects the characteristic wavelength of ultraviolet light that they emit, known as Lyman-alpha radiation.
New observations with numerous most powerful telescopes in the world-including the Atacama Large Millimeter Array (ALMA) in Chile, the ESO’s Very Large Telescope (VLT), and the Hubble Space Telescope-have revealed that two large galaxies engaging in furious star formation are at the center of the enormous cloud of gas that is SSA22-Lyman-alpha Blob 1, or LAB-1. The blob’s luminosity is caused by large and star-rich galaxies that were observed at the center of the blob. The light looks green to viewers on Earth, because its wavelength is stretched by the expanding universe during its long trip here.
That explains the glow of the blobs, why are they green?
The blob is one of the biggest and most mysterious objects in our universe. LAB-1 was discovered in 2000, located at about 11.5 billion light-years away from Earth. This means that the giant “blob” must be powered by galaxies embedded within the cloud. Each of the large central galaxies is about 30,000 to 60,000 light years across, while the smaller “satellite” galaxies average about 3,000 to 6,000 light years.
“Think of a streetlight on a foggy night – you see the diffuse glow because light is scattering off the tiny water droplets”, Dr. Geach said.
This diagram explains how a Lyman-alpha Blob, one of the largest and brightest objects in the uUniverse, shines.
“What’s exciting about these blobs is that we are getting a rare glimpse of what’s happening around these young, growing galaxies”, said Jim Geach, an astrophysicist from the University of Hertfordshire, U.K., who led the global research team.
Thanks to a combination of observations from the Atacama Large Millimeter/Submillimeter Array (ALMA), the Very Large Telescope (VLT), Hubble, and the Keck Observatory, we’ve got the first detailed look at what’s going on in there. A similar thing is happening here, except the streetlight is an intensely star-forming galaxy and the fog is a huge cloud of intergalactic gas. They said that the surrounding galaxies are likely delivering material for the duo’s rapid star formation. “Basically it is an environment that is very important for our understanding of how galaxies are growing, but is very hard to study”.
Jim Geach concludes, “What’s exciting about these blobs is that we are getting a rare glimpse of what’s happening around these young, growing galaxies”.
Lyman-alpha blobs are made up of hydrogen gas and the rapid star production activity is making the surrounding gas glow.
And it turns out the light show it puts on is more than pretty – it may be indicative of the birth of a massive cluster of galaxies.
“We are seeing a snapshot of the assembly of that galaxy 11.5 billion years ago”, co-author Dave Clements said in a statement.
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The SSA22-Lyman-alpha blob 1, or LAB-1, is part of a class of cold hydrogen gas accumulations called Lyman-alpha blobs. LAB-1 is an ancient artifact of the early universe, and studying it with other Lyman-alpha Blobs can help astronomers refine theories about galactic formation, the fabric of space-time, and the structure of the universe itself.
