02-04-2025
This Deep-Space Spiral Galaxy Does Something It Shouldn't
Scientists are scratching their heads after taking a closer look at 2MASX J23453268−0449256, a spiral galaxy with a mouthful of a name. Nearly 1 billion light-years from Earth, the galaxy contains something it shouldn't: a supermassive black hole with jets so powerful, the spiral should no longer be stable.
J2345-0449—as the galaxy is thankfully also known—was found in 2014, when astronomers in India hunted down a giant radio source known to possess relativistic jets, whose blasts of plasma travel at nearly the speed of light. Even then, the astronomers knew that J2345-0449 was strange: Relativistic jets are some of the universe's most powerful particle accelerators, and they're not typically found in spiral galaxies. Adding to the mystery was the size of J2345-0449's black hole, which the team considered "unusually massive" for a bulgeless disk galaxy.
They were right to be surprised. More than a decade later, the same astronomers have completed an in-depth investigation of J2345-0449 using the Hubble Space Telescope, the Giant Metrewave Radio Telescope, and the Atacama Large Millimeter Wave Array. Published last week in Monthly Notices of the Royal Astronomical Society, their findings highlight the galaxy's bizarre combination of structural components, which appear to contradict each other despite likely having "peacefully co-evolved."
J2345-0449's jets extend 6 million light-years away from its central supermassive black hole. Credit: Bagchi and Ray et al/Giant Metrewave Radio Telescope
J2345-0449 might be three times the size of the Milky Way, but its central supermassive black hole is even more intimidating: The astronomers say its mass is billions of times larger than our Sun's. (Sagittarius A, the Milky Way's black hole, is merely 4 million times as massive as the Sun.) Though black holes don't produce their own radiation, they can influence their surroundings in ways that do. J2345-0449 exhibits signs of suppressed star formation in its central region; while the mechanisms of star formation suppression aren't well known, the astronomers think feedback from J2345-0449's black hole is pumping the brakes.
Accretion disks are known to "reroute" material that would otherwise fall into a black hole. When that happens—or when an accretion disk squeezes infalling material—a plasma jet forms, spewing energy outward, away from the black hole. These blasts are believed to play a role in J2345-0449's suppression of star formation, which in turn could produce powerful radio jets.
But jets of this capacity would render any other spiral galaxy unstable. Galaxies of this type—including our own Milky Way—are considered too fragile for the immense turbulence produced by such jets, which could disturb the disk's wispy structure.
"This discovery is more than just an oddity—it forces us to rethink how galaxies evolve, and how supermassive black holes grow in them and shape their environments," lead study author Joydeep Bagchi told the Royal Astronomical Society.
