Galaxies come to life through the formation of stars from their clouds of dust and gas. However, a galaxy recently observed by the James Webb Space Telescope (JWST) has been dormant in star formation for a staggering 13 billion years.
This galaxy, known as JADES-GS-z7-01-QU, and its unusual behavior were detailed in a study initially shared last year on arXiv and later published in Nature on March 6.
Tobias Looser, a researcher at the Kavli Institute for Cosmology at the University of Cambridge and the study's lead author, remarked, "Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies transitioning from a phase of star formation to a dormant or quenched state."
The galaxy derives its name from the JWST Advanced Deep Galactic Survey (JADES), the project responsible for its observation.
Researchers discovered that the galaxy likely experienced a brief burst of star formation lasting between 30 to 90 million years. However, it ceased forming stars just 10 to 20 million years prior to the period captured in the observations. Since its light has traveled over 13 billion years to reach us, JWST observed it as it existed a mere 700 million years after the Big Bang, making it the oldest "dead" galaxy identified to date.
A galaxy can halt star formation when its central supermassive black hole pulls in interstellar dust, preventing the creation of new stars. Alternatively, rapid star formation can deplete a galaxy's dusty resources, inadvertently starving it of the necessary materials for new star formation. The team is uncertain whether the observed phenomenon was caused by either of these scenarios. Nonetheless, studying ancient galaxies aids astronomers in understanding galactic evolution and star formation processes, contributing to the development of more accurate models.
Galaxies seemingly ceasing star formation are not uncommon in astronomy. By the time the universe reached 3 billion years of age, approximately half of its massive galaxies had halted star formation. Observations from telescopes like Hubble and ESO's Very Large Telescope suggest that in these "dead" galaxies, star formation begins to dwindle from the core outward, with only the edges of their disks producing new stars.
The reason behind galaxies shutting down their star factories remains a subject of debate. It could be due to factors preventing gas from replenishing within galaxies or collisions and mergers altering their composition. Further observations, like those conducted by the JADES team, aim to shed light on these mysteries. Francesco D'Eugenio, a study co-author and researcher at the Kavli Institute for Cosmology, expressed the team's aspirations: "We're searching for similar galaxies in the early universe to help us understand how and why galaxies cease forming new stars. It's possible that galaxies in the early universe experience a 'death' only to later 'rebirth' — but more observations are needed to confirm this."
JADES-GS-z7-01-QU