Twelve years ago, researchers noticed that two colliding galaxies some 500 million light-years away were emitting a copious amount of infrared light.
While the precise origin of the illumination was impossible to pinpoint at the time, they were convinced the infrared illumination may have come from a "powerful energy source." Somewhere in that galactic merger known as IIZw096, was what the researchers called the "engine" of the collision.
And now, using the NASA's James Webb Space Telescope, which is capable of delivering the deepest infrared images ever taken of the universe, they've finally revealed where this mysterious entity resides once and for all, as detailed in a paper published in The Astrophysical Journal Letters late last year.
"We wanted to find the 'engine' that powers this merging galaxy system," explained study author Hanae Inami, an assistant professor at Hiroshima University's Astrophysical Science Center, in a new press release. "We knew that this source was deeply hidden by cosmic dust, so we could not use visible or ultraviolet light to find it."
"Only in the mid-infrared, observed with the James Webb Space Telescope, do we now see that this source outshines everything else in these merging galaxies," he added.
Roughly 500 million light-years away, two galaxies are colliding. Known as IIZw096, this luminous phenomenon is obscured by cosmic dust. Now, with the Webb Telescope, a team identified the exact location of the “engine” that powers the merging galaxy.🌌https://t.co/4PSrQ3HsFc
— Hiroshima University (@HiroshimaUnivEn) February 8, 2023
Small Source, Shining Bright
According to the researchers, the engine accounted for up to a whopping 70 percent of all the infrared light emitted from the merger — an astounding proportion, considering how small it is at a mere 570 light-years. To put that number into perspective, the entire system spans 65,000 light-years.
"It is intriguing that this compact source, far from the galactic centers, dominates the infrared luminosity of the system," said co-author and Hiroshima University researcher Thomas Bohn, who compared its size to a speck of pepper on a white egg.
In some ways, their findings incur more questions than answers. What exactly could be making this galactic engine so luminous?
Inami proposes that it could be a starburst or a massive black hole, but the team won't know for sure without an extensive follow-up investigation, and perhaps observations.
"It is also unusual that the 'engine' lies outside of the main parts of the merging galaxies, so we will explore how this powerful source ended up there," Inami added.
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