Astronomers have detected seismic ripples in the ancient galactic disk

Illustration of a galaxy disk being disturbed. Credit: Jonathan Bland-Hawthorn and Thorsten Tepper-Garcia/University of Sydney.

A new snapshot of an ancient, distant galaxy could help scientists understand how it formed and the origin of our own Milky Way. At over 12 billion years old, BRI 1335-0417 is the oldest and most distant known spiral galaxy in our universe.

Lead author Dr. Takafumi Tsukui said the state-of-the-art telescope ALMA allowed them to see this ancient galaxy in greater detail.

“In particular, we are interested in how the gas moves in and across the galaxy,” said Dr. Tsukui. “Gas is a key ingredient in star formation and can give us important clues about how a galaxy actually promotes its star formation.”

In this case, the researchers were able not only to capture the motion of the gas around BRI 1335-0417, but also to reveal a seismic wave formed first in this type of early galaxy. The study was published in Monthly Notices of the Royal Astronomical Society.

The galaxy’s disk, a flattened mass of spinning stars, gas and dust, moves in a way not unlike the ripples that spread across a pond after a stone is thrown.

“The vertically oscillating motion of the disk is caused by an external source, either from new gas flowing into the galaxy or through contact with other small galaxies,” said Dr. Tsukui. “Both possibilities pump the galaxy with new fuel for star formation.

“In addition, our study reveals a bar-like structure in the disk. Galactic bars can disrupt gas and transport it towards the center of the galaxy. The bar discovered in BRI 1335-0417 is the most distant known structure of this type. Together, these results show the dynamic growth of a young galaxy.”

Because BRI 1335-0417 is so far away, its light takes longer to reach Earth. The images seen through the telescope today are a throwback to the early days of the galaxy when the universe was only 10% of its current age.

“The first galaxies were found to form stars at a faster rate than modern galaxies. This is true for BRI 1335-0417, which, despite having a similar mass to our Milky Way, formed star at a rate several hundred times faster,” co-author Associate Professor Emily Wisnioski said.

“We want to understand how the gas supply is able to sustain the rapid rate of star formation.

“Spiral structures were rare in the early universe, and how they formed is also unknown. This study also gives us important information on the most possible scenarios.

“While it is impossible to directly observe the evolution of the galaxy, because our observations only give us a snapshot, computer simulations can help piece the story together.”

More information:
Takafumi Tsukui et al, Detection of a disk bending wave in a barred-spiral galaxy at redshift 4.4, Monthly Notices of the Royal Astronomical Society (2023). DOI: 10.1093/mnras/stad3588. academic.oup.com/mnras/advance ras/stad3588/7445010

Awarded by the Australian National University

Citation: Astronomers see seismic ripples in ancient galactic disk (2023, December 21) Retrieved December 21, 2023 from https://phys.org/news/2023-12-astronomers-seismic-ripples-ancient-galactic .html

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