NASA’s Hubble Space Telescope is at it again with a discovery dating back more than 8 billion years ago. Using one hell of a natural magnifying lens (gravitational lensing), the Hubble can tease out details of far-flung galaxies.
You’re looking at galaxies that existed between 8 billion and 11.5 billion years ago. The weird rings and arcs seen in the image above are the result of gravitational lensing from the foreground galaxy distorting the image.
“We have hit the jackpot of gravitational lenses,” says lead researcher James Lowenthal. “These ultra-luminous, massive, starburst galaxies are very rare. Gravitational lensing magnifies them so that you can see small details that otherwise are unimaginable. We can see features as small as about 100 light-years or less across.”
Here’s a quick rundown on gravitational lensing. Astronomers look for a massive galaxy or cluster of galaxies. The extraordinary gravity from this foreground target magnifies the light of the galaxies ‘behind’ it or further away. The bigger the galaxy or cluster, the more magnifying power you get.
These bright galaxies are up to 10,000 times more luminous than our Milky Way. And were pumping stars out at a rate of 10,000 per year. Using the same amount of gas as we see in the Milky Way according to researchers. It’s a mystery that still stumps researchers.
“There are so many unknowns about star and galaxy formation,” said Lowenthal. “We need to understand the extreme cases, such as these galaxies, as well as the average cases, like our Milky Way, in order to have a complete story about how galaxy and star formation happen.”
Studying these images isn’t as easy as just snapping a picture with Hubble. The researchers have to deconstruct what they’re looking at. The foreground galaxy causes a lot of distortion. “We need to understand the nature and scale of those lensing effects to interpret properly what we’re seeing in the distant, early universe,” Lowenthal explains.
Galaxies like this are very rare. At least, in the parts of the sky we’ve already looked in. Hubble’s deep field surveys have revealed none of these star-churning factories. Lowenthal says they are littered in random parts of the sky that telescopes haven’t looked at yet. At least, not in-depth observations.
Lowenthal and his colleagues plan to fire up the Hubble again, along with the Gemini Observatory in Hawaii, to study these distant galaxies in even greater detail.
How can a galaxy produce 10,000 stars/year?
Two possibilities are raised in the research. The first is galaxy collisions. Ultra-luminous infrared galaxies (ULIRGS) see insane star production after two spiral galaxies merge. But Lowenthal says computer models show these mergers happening at a later time in the universe’s life.
Another theory suggests huge amounts of gas was flowing into galaxies during the early universe. “The early universe was denser, so maybe gas is raining down on the galaxies, or they are fed by some sort of channel or conduit, which we have not figured out yet,” said Lowenthal. They just don’t have a good answer yet to explain how these galaxies are producing stars at such a fast rate.