Early galaxy seen creating clear 'bubbles' in the foggy universe

The early universe was no serene place. Born from cosmic fire, it cooled down as space expanded. Soon, matter clumped together as gravity began to pull. Galaxies emerged from vast clouds of gas, surrounded by dense fog. As they formed, they began carving out clear bubbles in this fog.

How early these galaxies and their bubbles appeared still puzzles scientists. Yet, recent discoveries push these cosmic beginnings closer to the time of the Big Bang than ever imagined.

Hidden in fog

The universe’s first few hundred million years remained cloaked in dense gas. New galaxies, glowing in ultraviolet (UV) light, struggled to be seen.

The reason? Neutral hydrogen filled the space between them. This gas blocked the bright UV signals and acted like a cosmic fog.

As a result, most early galaxies became invisible at UV wavelengths. Observing them was nearly impossible. The light they emitted couldn’t break through the fog.

Yet, understanding these earliest objects requires seeing through that haze. Something had to change in the cosmic fabric.

The fog begins to clear

The first stars and galaxies didn’t just light up the cosmos. Their UV light started breaking apart the neutral hydrogen around them. Slowly, space became more transparent.

This dramatic shift is called the Epoch of Reionization. It marked the moment when light began traveling freely.

But until now, astronomers believed the process started half a billion years after the Big Bang and took another half billion to finish.

A new discovery challenges this timeline.

Galaxy bubbles started clearing fog

Astronomers at the Cosmic Dawn Center (DAWN) have made a breakthrough. They studied a galaxy named JADES-GS-z13-1 that lies among the oldest ever detected. It stood out because it shines so brightly.

“Young galaxies shine brightest at a very specific wavelength of light, originating from hydrogen,“ noted Joris Witstok, lead researcher from the University of Cambridge.

“To astronomers, this light goes under the name ‘Lyman alpha.’ Because of its short UV wavelength, it is easily absorbed by the surrounding medium, and therefore no galaxy from when the universe was less than half a billion years old has showed us this particular kind of light.”

Galaxy formed a bubble that cleared space around it

How did this light escape the fog that was so prevalent at that time?

Witstok’s team believes the galaxy created a local bubble of clear space. Its UV light “fried” the nearby neutral gas.

What remained was a transparent pocket – an ionized bubble. These bubbles, once they were numerous enough, reionized the whole universe.

“We believe that we have discovered one of the first such bubbles,” Witstok said.

That light escaping from JADES-GS-z13-1 could only do so from inside such a bubble. It’s direct evidence of reionization that was already underway, much earlier than anyone thought.

James Webb’s vital role

These observations became possible thanks to the James Webb Space Telescope. Its sensitive instruments allow scientists to examine distant galaxies in precise detail.

“We knew that we would find some of the most distant galaxies when we built Webb. But we could only dream of one day being able to probe them in such detail that we can now see directly how they affect the whole universe,” noted Peter Jakobsen, a key figure behind Webb’s NIRSpec tool.

What caused the bubble?

The source of this ionized bubble remains uncertain. The first stars, likely very hot and UV-bright, could have created it. But another explanation also exists.

Supermassive black holes emit intense radiation as they consume gas. This process heats the gas to millions of degrees, and that energy could also have carved out the bubble.

“Most galaxies are known to host a central, supermassive black hole,” said Witstok. “This is another viable cause of the bubbles, which we will now investigate.”

As astronomers study more ancient galaxies, these light bubbles might offer the clearest view yet into the universe’s formative moments.

Early bubbles shift theories on galaxies

The discovery of Lyman alpha light from JADES-GS-z13-1, and the evidence of ionized bubbles, marks a major milestone in our understanding of the universe’s early years.

It challenges existing theories and opens new avenues for exploring how the first galaxies formed and began to influence the surrounding environment.

As scientists continue to study these ancient objects with advanced tools, like the James Webb Space Telescope, we can expect to uncover even more secrets of the cosmos’s infancy.

The re-ionization process, once thought to have begun later in the universe’s history, may actually have started much earlier, which reshapes our view of the cosmic timeline.

The study is published in the journal Nature.

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