Since they were first discovered 16 years ago, scientists have been wondering how and why the unusual objects known as Lyman-alpha blobs – gigantic clouds of hydrogen gas which glow 10 times more brightly than the Milky Way – were so bright, or why the even existed at all.
Now, as the Washington Post reported Thursday morning, they have found their answer: using the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile, a team of researchers has discovered that Lyman-alpha blob 1 (the original object discovered by Caltech astronomers back in 2000) contained a pair of young galaxies creating new stars at an extremely fast pace.
This activity causes the cloud of gas enveloping these stars to glow like “a streetlight on a foggy night,” lead author Jim Geach, an astronomer with the University of Hertfordshire, told the Post. “You see the diffuse glow because light is scattering off the tiny water droplets. 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. The galaxies are illuminating their surroundings.”
Geach and his colleagues believe that their discovery could help scientists better understand how galaxies form and evolve. The two located at the heart of Lyman-alpha blob 1 are currently in the first stages of their development, but eventually, they will likely merge into one elliptical galaxy, similar to but considerably larger than our own Milky Way, the newspaper explained.
Findings could shed new light on formation, evolution of galaxies
Lyman-alpha blob 1 (also known as LAB-1) is one of the largest and most thoroughly analyzed objects of its kind, the researchers explained in a statement. It is three times larger than the Milky Way (measuring 300,000 light years across) and is so far away that its light takes approximately 11.5 billion light years to reach the Earth, they added in a second press release.
Most experts believe that LABs are the incubators in which the universe’s most massive galaxies form, which is why this new research – published recently in The Astrophysical Journal – is such an important breakthrough in understanding the evolution of galaxies The glow which surrounds these objects in particular could lead to new discoveries about the processes that occur within the difficult-to-study primordial gas clouds surrounding young galaxies.
“Unveiling the galaxies shrouded in LAB-1 did more than just put to bed the longstanding issue of the gas cloud’s glow,” explained study co-author Desika Narayanan of Haverford College in Pennsylvania. “It provided a rare opportunity to see how young, growing galaxies behaved when the universe was quite young.”
“What’s exciting about these blobs is that we are getting a rare glimpse of what’s happening around these young, growing galaxies,” said Geach. “For a long time, the origin of the extended Lyman-alpha light has been controversial. But with the combination of new observations and cutting-edge simulations, we think we have solved a 15-year-old mystery: 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. We are seeing a snapshot of the assembly of that galaxy 11.5 billion years ago.”
Image credit: J.Geach/D.Narayanan/R.Crain