When we look up at the night sky, we are not just seeing stars and distant galaxies.
We are also seeing a faint “afterglow” of the universe, a sort of cosmic background light that has been traveling across space for nearly 13.8 billion years.
This glow, known as the cosmic microwave background radiation, is a key piece of evidence for the Big Bang—the massive explosion that is believed to have created the universe.
But new research suggests that this afterglow might not be exactly what we thought.
Scientists from the Universities of Bonn, Prague, and Nanjing have found evidence that early galaxies, specifically elliptical galaxies, may have contributed more to this afterglow than previously believed.
Their study, published in the journal Nuclear Physics B, argues that these early galaxies may account for at least 1.4% of the background radiation.
While that might seem like a small number, it is enough to challenge some of the core ideas of modern cosmology.
The cosmic microwave background radiation is like a snapshot of the universe just 380,000 years after the Big Bang.
Before this time, the universe was a hot, dense soup of particles that prevented light from traveling freely.
But as the universe expanded and cooled, electrons and protons began to combine into neutral hydrogen atoms, allowing light to spread out across space. That light is what we now see as the cosmic background radiation.
For decades, scientists believed that tiny ripples in this background light were proof that matter was unevenly distributed in the early universe. These ripples indicated that some areas of space were denser than others, which eventually led to the formation of stars and galaxies.
However, the new study calls this idea into question. According to Professor Pavel Kroupa from the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn and Charles University in Prague, their calculations suggest that the strength of this background radiation might have been overestimated.
In fact, Kroupa and his colleague Dr. Eda Gjergo from the University of Nanjing believe that some of this radiation could have come from powerful star formations in early elliptical galaxies, not just from the Big Bang.
Elliptical galaxies are some of the oldest types of galaxies in the universe. They formed relatively quickly after the Big Bang, accumulating massive amounts of gas that ignited into hundreds of billions of stars.
These stars burned so brightly that their light could still be contributing to the cosmic background radiation we measure today.
Kroupa and Gjergo’s research suggests that these early galaxies might have created enough radiation to make up a significant part of what we assumed was solely the afterglow of the Big Bang.
If their findings are correct, it could mean that the standard model of cosmology—the theory that explains the origin and structure of the universe—might need to be revised. “Our results are a problem for the standard model of cosmology,” said Kroupa. “It might be necessary to rewrite the history of the universe, at least in part.”
The idea that early galaxies played a role in creating the universe’s afterglow opens up new questions about how galaxies formed and how much of the universe’s background radiation is truly left over from the Big Bang.
Kroupa and Gjergo’s findings suggest that our understanding of the universe’s early moments might be more complicated than we once thought. With further research, scientists hope to uncover whether this powerful “star fire” from early galaxies is just a small part of the universe’s afterglow—or something far more significant.
Source: University of Bonn.
