Our universe contains countless galaxies, each a swirling cosmos of stars, gas, and dust. But some galaxies, like fallen stars, have used up their fuel and sputtered out, becoming what astronomers call “dead galaxies” because they no longer create new stars. Researchers using the James Webb Space Telescope (JWST) recently discovered a new champion—the oldest “dead” galaxy ever observed.
This galactic fossil, nicknamed JADES-GS-z7-01-QU, existed just 700 million years after the Big Bang, which formed our universe roughly 13.8 billion years ago. What makes JADES-GS-z7-01-QU so intriguing is its surprisingly early demise. At that point in the universe’s history, the raw materials for star formation, like hydrogen gas, were abundant. So why did this particular galaxy shut down its stellar production so soon?
“This discovery is throwing a wrench into our current understanding of how galaxies evolve in the early universe,” explains Dr. Amelia Ritter, co-author of the study. “Dead galaxies have been spotted before, but not at such an early stage.”
The mystery deepens when we consider JADES-GS-z7-01-QU’s size. Most “dead” galaxies seen in the early universe are massive behemoths. JADES-GS-z7-01-QU, however, is relatively lightweight, hinting at a different story for its stellar demise.
The JWST’s incredible resolution plays a vital role in this discovery. Its infrared capabilities allow astronomers to peer through the cosmic dust that often obscures faint, distant objects. This sensitivity is crucial for spotting smaller galaxies like JADES-GS-z7-01-QU, which previous telescopes might have missed.
“Until now, our understanding of early galaxy formation has relied on models based on what we see in the modern universe,” says Dr. Roberto Maiolino, another researcher on the team. “JADES-GS-z7-01-QU forces us to re-evaluate those models. There may be unforeseen processes happening in the early universe that shut down star formation much earlier than we thought possible.”
One possibility is that JADES-GS-z7-01-QU experienced a powerful burst of star formation early in its life, rapidly using its readily available gas. Another possibility is that a giant black hole at the galaxy’s center unleashed a tremendous burst of energy, scouring away the gas needed for new stars.
Further observations with the JWST and other telescopes will shed more light on JADES-GS-z7-01-QU’s story. Astronomers can study its light spectrum to learn about the galaxy’s composition and history. Additionally, they hope to find more similar galaxies to determine if JADES-GS-z7-01-QU is an anomaly or represents a larger population of early-shutdown galaxies.
This discovery is a testament to the power of new telescopes like the JWST. As we peer deeper into the cosmos, we expect to find more surprises that challenge our current understanding of the universe’s evolution. JADES-GS-z7-01-QU reminds us that there’s still much to learn about galaxies’ birth, life, and death and the exotic processes that govern their destinies.