ALMA spots candidate for farthest known spiral galaxy | Astronomy

The star-forming disk galaxy with a two-armed spiral morphology, named BRI 1335-0417, existed when the Universe was only 1.4 billion years old.

BRI 1335-0417 was discovered in data from the Atacama Large Millimeter / submillimeter Array (ALMA).

“I was excited because I had never seen such clear evidence of a rotating disk, spiral structure, and centralized mass structure in a distant galaxy in any previous literature,” said the lead author Takafumi Tsukui, a graduate student at SOKENDAI.

“The quality of the ALMA data was so good that I was able to see so much detail that I thought it was from a nearby galaxy.”

Tsukui and his colleague, Professor Satoru Iguchi of SOKENDAI and the National Astronomical Observatory of Japan, discovered that BRI 1335-0417 has a two-armed spiral morphology that extends from approximately 6,500 to 16,300 years. – ray light.

“Because BRI 1335-0417 is a very distant object, we may not be able to see the true edge of the galaxy in this observation. For a galaxy that existed at the start of the Universe, BRI 1335-0417 was giant, ”Tsukui said.

Astronomers have interpreted the characteristics of BIS 1335-0417 as due to a compact central structure, such as a bulge; a rotating gas disc; and either spiral arms or tidal tails.

They had formed in the 1.4 billion years after the Big Bang, well before the peak of cosmic star formation.

“So the question becomes, how did this distinct spiral structure form in just 1.4 billion years after the Big Bang?” We have considered several possible causes and believe it could be due to an interaction with a small galaxy, ”they said.

“BRI 1335-0417 actively forms stars, and we have found that the gas in the outer part of the galaxy is gravitationally unstable, which is conducive to star formation.”

“This situation is likely to occur when a large amount of gas is supplied from the outside, possibly due to collisions with smaller galaxies.”

“The fate of BIS 1335-0417 is also shrouded in mystery. The galaxies that contain large amounts of dust and actively produce stars in the ancient universe are believed to be the ancestors of the giant elliptical galaxies in the present universe.

“In this case, BIS 1335-0417 changes its shape from a disk galaxy to an elliptical galaxy in the future. Or, unlike conventional view, it can remain a spiral galaxy for a long time.

the results were published in the journal Sciencee.

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Takafumi Tsukui and Satoru Iguchi. Spiraling morphology in an intensely star-forming disk galaxy over 12 billion years ago. Science, published online 20 May 2021; doi: 10.1126 / science.abe9680