The early universe was warmer than previously thought before the first stars and galaxies formed, according to a new study from the International Centre for Radio Astronomy Research (ICRAR).
Why it matters: The findings challenge the assumption that the universe emerged from an ultracold state and suggest that heating mechanisms were already in place before the formation of the first stars.
The details:
- Astronomers used the Murchison Widefield Array (MWA) radio telescope in Western Australia to hunt for a signal called the 21-centimeter line, which carries information about the cosmic dark ages.
- The team observed the sky for longer than ever before by integrating about 10 years of MWA data.
- While the long-sought hydrogen line has not been detected yet, the high-quality data reveals that the early cosmos was in a pre-heated state before reionization took place.
- The heating is likely driven by the energy from early sources of X-rays from stellar remnants spreading through the universe.
The research focused on investigating the “Epoch of Reionization,” a critical period that marked the end of the Cosmic Dark Ages, around a billion years after the Big Bang.
What they’re saying:
- “As the Universe evolved, the gas between galaxies expands and cools, so we would expect it to be very, very cold,” said Cathryn Trott, radio astronomer and lead of the Epoch of Reionization project at ICRAR. “Our measurements show that it is at least heated by a certain amount. Not by a lot, but it tells us that very cold reionization is ruled out.”
- “The signal is definitely buried in there. It’s just about improving our data, and getting more, cleaner data, to reach it,” said Ridhima Nunhokee, a radio astronomer at ICRAR.
What’s next: With upcoming advances and more data, the team believes it might only be a matter of time before the hydrogen line is finally detected, providing further insights into the early universe.
