A team of 48 astronomers from 14 countries, led by the University of Massachusetts Amherst, has discovered a population of dusty, star-forming galaxies. These galaxies formed approximately one billion years after the Big Bang, which is believed to have occurred 13.7 billion years ago. The discovery was published in The Astrophysical Journal Letters.
Significance of the Discovery
These newly identified galaxies may represent a critical stage in the galactic lifecycle. They could link ultradistant bright galaxies that formed 13.3 billion years ago with early "quiescent" (dead) galaxies that ceased forming stars about two billion years after the Big Bang. This finding suggests that star formation occurred earlier in the universe's evolution than previously understood, challenging current models of the universe.
Jorge Zavala, assistant professor of astronomy at UMass Amherst and the paper's lead author, stated that dusty galaxies are massive and contain significant amounts of metals and cosmic dust. He noted that their ancient age indicates star formation took place in the early universe, earlier than current models predict.
Methodology
Studying these galaxies has been challenging due to dust, which absorbs UV and visible light, rendering them invisible to traditional telescopes. The team utilized submillimeter telescopes, which can detect longer-wavelength light and the infrared energy radiated by heated dust.
Researchers initially used the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile to identify approximately 400 bright, dusty galaxies. They then employed near-infrared observations from NASA's James Webb Space Telescope (JWST) to pinpoint about 70 faint dusty galaxy candidates at the edge of the universe, many of which had not been observed before. By "stacking" previous ALMA data, the team confirmed these were indeed dusty galaxies formed almost 13 billion years ago.
Implications for Cosmic History
If the hypothesis proposed by Zavala and his team is confirmed, it implies that current astronomical models of the universe's formation may be incomplete. The new galaxies provide a "snapshot" likened to "young adults" in the lifecycle of rare galaxies, positioned between "young" ultrabright galaxies and "old" quiescent galaxies.
Support
The research received funding from the U.S. National Science Foundation and involved a broad international collaboration.