Imagine the candles on its birthday cake: Astro-eggheads detect galaxy born in universe's first billion years

Earth-based 'scope clocks one of this simulation's first wonders

The Large Millimetre Telescope ... Image Credit: UMass Amherst

A large international team of astronomers has detected one of the oldest galaxies in the universe we've seen to date – born within a billion years after the Big Bang.

That would make it one of the very first things to form in our fledgling universe.

The now-elderly galaxy, codenamed G09 83808, was first glimpsed during a scan of the heavens by the orbiting Herschel Space Observatory, and appeared as a blurry blob, making it difficult to analyze.

Now, researchers from the University of Massachusetts Amherst in the US, and the Instituto Nacional de Astrofísica, óptica y Electrónica in Mexico, have taken a closer look at the timeworn wonder using the Earth-based Large Millimeter Telescope (LMT) and studied it in more detail. Their findings were published in a Nature paper on Monday. The executive summary: G09 83808 was formed roughly 12.8 billion years ago.

Min Yun, coauthor of the paper and a professor at UMass Amherst, said: "The Big Bang happened 13.7 billion years ago, and now we are seeing this galaxy from 12.8 billion years ago, so it was forming within the first billion years after the Big Bang.

"Seeing an object within the first billion years is remarkable because the universe was fully ionized, that is, it was too hot and too uniform to form anything for the first 400 million years. So our best guess is that the first stars and galaxies and black holes all formed within the first half a billion to one billion years. This new object is very close to being one of the first galaxies ever to form."

Scientists use redshift to measure the distance of such faraway objects. The higher the value of redshift, the further away it is. G09 83808 is a rare find with a redshift of 6.027. Only two galaxies have been found with a redshift of more than 6 so far. The most far flung galaxy, SPT0311?58, was first reported in June with a redshift of 6.9, and the second most distant one has a redshift of 6.34.

Yun calls these high redshift, very distant objects “mythical beasts in astrophysics.” “We always knew there were some out there that are enormously large and bright, but they are invisible in visible light spectrum because they are so obscured by the thick dust clouds that surround their young stars,” he said.

Ancient

It’s difficult to study these bright ancient galaxies using optical telescopes like Hubble Space Telescope or the far infrared and sub-millimetre Herschel Space Observatory, because even though they are flying through the seemingly pure obsidian void, they can be shrouded by clouds of thick cosmic dust used to form new stars.

The LMT, meanwhile, is our planet's largest single-dish steerable millimetre-wavelength radio telescope, located at the top of Volcán Sierra Negra, an extinct volcano in Puebla, Mexico. It can trace carbon monoxide spectral lines used to calculate redshift.

The research team also relied on gravitational lensing, a phenomenon that magnifies the light coming from distant galaxies as it closely passes massive objects, to make G09 83808 look about ten times brighter and closer than it is, making it easier to study.

The LMT is expected to be operate at a higher resolution and sensitivity in the next few months, which could help the eggheads find even more ancient galaxies.

"Now, it could be that there are a whole bunch of them out there and we haven't been able to see them, but with the LMT we have the power to see them. Maybe they'll start popping out," Yun said.

"We are in the discovery field. Every time I reduce one of these data sets I'm full of anticipation. I'm always hoping that these things will pop out. You have to be a hopeless optimist to be doing this kind of work, and this time it absolutely paid off." ?


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