Peering deep into the cosmos with the Very Large Telescope’s X-shooter instrument, astronomers have observed one of the youngest and most remote galaxies ever discovered.
The galaxy, A1689-zD1, was around when the universe was just 700 million years old. Or, 5% of its current age.
“After confirming the galaxy’s distance using the VLT,” said Darach Watson, lead author of the paper. “We realised it had previously been observed with ALMA. We didn’t expect to find much, but I can tell you we were all quite excited when we realised that not only had ALMA observed it, but that there was a clear detection. One of the main goals of the ALMA Observatory was to find galaxies in the early Universe from their cold gas and dust emissions — and here we had it!”
What shocked astronomers was how evolved the system already was.
Galaxies this young tend to lack heavier elements. Basically, anything heavier than hydrogen and helium. In order for other elements to form, such as carbon and nitrogen, stars have to form and then explode. After several generations of star forming and subsequent explosions, you would start seeing other elements formed in significant quantities.
Observations of A1689-zD1 show it emitting tons of radiation in the far infrared. This shows it was already busy producing stars and has significant quantities of metals. Plus, it contained a dust-to-gas ratio comparable to our Milky Way galaxy.
“Although the exact origin of galactic dust remains obscure,” explains Darach Watson, “our findings indicate that its production occurs very rapidly, within only 500 million years of the beginning of star formation in the Universe — a very short cosmological time frame, given that most stars live for billions of years.”
This discovery is just the latest that shows our understanding of the early universe is still in its infancy. Last week, astronomers spotted a gigantic black hole during one of the earliest points in the universe.
Kirsten Knudsen, co-author of the paper, hopes to find similar galaxies in the future with the Atacama Large Millimeter/submillimeter Array (ALMA). And, find out what is causing them to grow so fast.
Image credit: ESA
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