A galaxy whose light traveled almost 13.5 billion years to arrive at Earth has been confirmed as the first galaxy ever discovered.
By studying the oxygen content of the galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have exactly dated it to just 367 million years after the Big Bang, a time when the first lights in the Universe were still switching on and beginning to propagate freely through space.
The result confirms the observations of the JWST and provides new information about the early Universe which tells us about the origins of the elements.
“The first images of the James Webb Space Telescope revealed a great deal of early galaxies that we felt we needed to check its results using the very best observatory on Earth,” Tom Bakx, an astronomer at Nagoya University in Japan, said.
“It was a very exciting moment to become an observational astronomer, since we could monitor the status of the observations which will test the JWST results in real time,” he said.
The galaxy, known as GHZ2 / GLASS-z12, was first spotted by JWST in July of last year, not long after the telescope opened its segmented golden eye on the infrared illumination of the Universe.
A paper in November detailed the discovery, dating the universe directly to more or less 350 million years after the Big Bang, which took place around 13.8 billion years ago.
That’s really very amazing, but any astronomical finding is a lot more powerful if it could be verified with an independent instrument.
A group led by Bakx as well as the astronomer Jorge Zavala of the National Astronomical Observatory of Japan turned on the ALMA radio telescope to find out what more they might find out about the small galaxy.
They aligned ALMA in the direction of GHZ2 / GLASS z12 and started looking for an emission signature on the radio spectrum related to oxygen.
Since oxygen takes just a short time to develop, it’s commonly used to find out about galaxies of the early Universe. So when light enters oxygen, it’s reemitted at a particular wavelength range, leading to a brighter line in that part of the spectrum.
Each of the 66 12-meter radio antennae that make up ALMA was analyzed and ultimately found an oxygen emission line at the position of GHZ2 / GLASS-z12. Follow-up tests as well as statistical tests determined the signal was real and related to the galaxy.
“We were initially worried about the small variation between the detected oxygen emission line as well as the galaxy seen by Webb,” Bakx said in a statement.
“However, we’ve performed detailed tests on the observations to make certain this really is a robust detection and it is extremely hard to describe via any other interpretation,” he said.
The very small distance between the galaxies and oxygen emission might suggest that violent explosions or interactions have removed a good deal of gasoline out of the galaxy, blowing it into intergalactic space.
The experts dated the facts to 367 million years following the big Bang. Based on the brightness of the emission line, they were able to infer the galaxy had created huge abundances of elements heavier compared to hydrogen and helium relatively quickly.
This is really fascinating. The first Universe before the stars came along was largely made of hydrogen with a tiny amount of helium. Stars then formed. They started smashing atoms together within their hot, thick cores, creating heavier components.
These components were, nevertheless, locked inside the stars. Just after the stars died and exploded in incredible supernovas was it feasible for heavier elements to spread through interstellar space.
This early presence of oxygen in the Universe provides us with some indications concerning the development and timing of these first stars, that we have yet to see directly.
“These deep ALMA observations provide strong proof of the presence of galaxies within the first couple of hundred thousand years after the Big Bang and confirm the shocking results from the Webb observations,” said Zavala.
“The work of JWST has just just begun, but we are currently modifying our models of just how galaxies form in the early Universe to match these observations,” he said. The combined capability of Webb and the ALMA radio telescope array gives us confidence to push our cosmic horizons even closer to the dawn of the universe.
The research has been published in the Monthly Notices of the Royal Astronomical Society.