James Webb Telescope gets closer to detecting what has Ionized the Universe

(ORDO NEWS) — Astronomers have determined that so-called “holey” galaxies may be responsible for triggering the last great transformational epoch in our universe, which ionized neutral interstellar gas.

Billions of years ago, our universe was much smaller and much hotter than it is today. In very early times, it was so small and hot that it was in a state of plasma, where electrons were separated from atomic nuclei.

But when the universe was about 380,000 years old, it cooled to the point where electrons could recombine at their nuclei to form a soup of neutral atoms.

Observations of the modern universe show that almost all matter in the universe is not neutral. Instead, it ionizes in a plasma state.

Over the past billions of years, something had to happen for the neutral gas of space to turn into ionized plasma.

Astronomers call this event the epoch of reionization and suspect that it occurred in the first few hundred million years after the Big Bang. But there is no certainty how this transformational event took place.

One of the biggest controversies in modern cosmology concerns the source of reionization. One hypothesis is that quasars are responsible.

Quasars are superluminous nuclei that surround supermassive black holes that emit massive amounts of high-energy radiation. It can easily flood the universe and turn it from neutral to ionized.

But the problem with this hypothesis is that quasars are relatively rare, and therefore difficult for them to cover the volume of the universe.

Another hypothesis is that young galaxies rich in star formation are responsible. In this scenario, the process of neutral gas ionization is more common in the Universe.

Each individual galaxy is able to ionize gas only in its immediate vicinity, but since there are so many galaxies, it is possible to reionize the entire Universe.

But the only way to do that is if enough high-energy radiation leaks out of the galaxies and into the environment.

James Webb Telescope gets closer to detecting what has Ionized the Universe 2

One group of astronomers used the James Webb Space Telescope to investigate this hypothesis.

They cannot study radiation from galaxies directly, because it is absorbed by matter billions of light-years between us and these galaxies. So instead, scientists had to look for other clues.

Using James Webb’s ability to study distant galaxies, they were able to measure how compact they are and how rich in star formation.

They were then able to compare the galaxies with similar galaxies found in the modern universe to estimate the amount of radiation leaking from them.

They estimate that, on average, galaxies in the early universe let through roughly 12% of the available high-energy photons.

This is just enough to potentially reionize the entire cosmos in a relatively short amount of time.

The results are not definitive due to a number of assumptions that astronomers had to make. But it points to an intriguing direction in solving this longstanding cosmic mystery.


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