 *This image from the James Webley Space Telescope contains approx. In the center of this image — the pink, six-pronged blob of light — is quasar J0100+2802, as seen when the universe was only 900 million years old. Credits: NASA, European Space Agency, Canadian Space Agency, Simon Lilly (ETH Zurich), Daiichi Kashino (Nagoya University), Jorit Matei (ETH Zurich), Christina Eilers (MIT), Rob Simko (MIT), Rungmon Bordoloi (NCSU), Roy Mackenzie (ETH Zurich), Alyssa Pagan (STScI), Ruari Mackenzie (ETH Zurich)*
A long time ago, when the universe was young, it was hard to see. During the first billion years or so after the Big Bang, the space between stars and galaxies was filled with clouds of cooled hydrogen gas, which absorbed all light. As a result, if any intelligent life existed at that time, they would see nothing but darkness in space – no other stars or galaxies would be visible to them.
Then came a time that astronomers have called the era of reionization, when all hydrogen gas turned from opaque to transparent as it heated up and ionized. Astronomers knew this process happened (we wouldn’t see the universe even if it didn’t). Until now, though, they had no hard evidence of how this happened.
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Now, a team of researchers – Emission Line Galaxies and Intergalactic Gas in the Age of Reionization, or EIGER – led by Simon Lilly of ETH Zürich in Switzerland, has used the James Webb Space Telescope to solve this mystery.
Focusing Webb on a small region of space between the constellations Pisces and Andromeda, the team pointed the telescope directly at an ancient bright object known as quasar J0100+2802. A quasar is a supermassive black hole at the heart of a galaxy that emits huge amounts of energy as it consumes matter. Quasars are some of the One of the brightest objects in the universe.
This artist’s impression depicts what a distant quasar might look like up close. Credit: ESO/M. Kornmisser
However, the EIGER team wasn’t just interested in the quasar itself. They also used Webb to observe how light from the quasar behaves as it passes through the gases along the path from J0100+2802 to the telescope’s instruments.
“As the quasar’s light traveled towards us through different patches of gas, it was either absorbed by opaque gas or moved freely through transparent gas,” NASA said.
By adding data from Webb to similar observations collected by the W.M. Keck Observatory in Hawaii, as well as ESO’s Very Large Telescope and the Magellan Telescope at Las Campanas Observatory, the EIGER team has matched the light’s behavior to the positions of early galaxies visible along line-of-sight to J0100+2802.
Photographed by NASA’s James Webb Space Telescope, these six galaxies appeared as they appeared when the universe was only 900 million years old. Credits: NASA, European Space Agency, Canadian Space Agency, Simon Lilly (ETH Zurich), Daiichi Kashino (Nagoya University), Jorit Matei (ETH Zurich), Christina Eilers (MIT), Rob Simko (MIT), Rungmon Bordoloi (NCSU), Roary Mackenzie (ETH Zurich); Image processing: Alyssa Pagan (STScI) and Rawari Mackie
“[These early galaxies] more chaotic than that of the near universe,” Jorit Mate of ETH Zürich, lead author of the book One Of the team’s three papers based on these observations, V press release. “Webb shows that they were actively forming stars and must have been launching many supernovae. They had quite an adventurous young man!”
The results revealed that each galaxy was surrounded by a shroud of hot, ionized, transparent gas with a radius of two million light-years. For a sense of scale, our galaxy’s nearest large neighbor, the Andromeda Galaxy, is about 2.5 million light-years away.
“Not only does Webb clearly show that these transparent regions exist around galaxies, but we also measured their size,” said Daichi Kashino of Nagoya University, lead author of the book. last Of the papers written by the team, illustrated in Press release. “Using Webb’s data, we see galaxies reionizing the gas around them.”
As summarized in the chart below, the very first galaxies in the universe, themselves, were responsible for bringing about the age of reionization.
The four stages of the reionization era. Credit: NASA, ESA, CSA, Joyce Kang (STScI)
As they go through bouts of star formation and stellar death through supernovae, the radiation from these galaxies is what heats and ionizes hydrogen gas, turning it from opaque to transparent. These bubbles of transparent ionized gas then expanded and fused together, allowing light to travel far across the universe.
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More puzzles to solve
Even as they answered the question of what was ultimately responsible for the transparent universe we see today, this team of researchers also added another growing mystery about the early universe.
Given what we know about star formation and how stars cluster together into galaxies, astronomers thought they had a good idea of how many galaxies they had found in the early universe. but, The numbers revealed by Webb Far exceeds those expectations.
“We expected to identify a few dozen galaxies that were present during the era of reionization – but we easily managed to identify 117,” explained Kashino.
Also, the data Webb collected allowed the team to measure the mass of the supermassive black hole that powers quasar J0100+2802. They found that it tipps cosmic scales at about 10 billion times the mass of our sun. This makes it the largest known supermassive black hole in the early universe.
Anna Christina Ehlers of MIT, lead author of the team book Third paperto NASA.
“This is another mystery to be solved!”
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