Astronomers detect seismic ripples in ancient galactic disk

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

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

“Specifically, we were interested in how gas moved in and through the galaxy,” Dr Tsukui said. “Gas is a key ingredient for star formation and can give us important clues about how a galaxy actually fuels its star formation.”

In this case, researchers were able to not only capture the movement of gas around BRI 1335-0417, but also reveal the formation of a seismic wave, a 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 rotating stars, gas and dust, moves in a way not unlike the ripples that spread across a pond after a stone is thrown into it. .

“The vertical wobble motion of the disk is due to an external source, either from new gas entering the galaxy or by coming into contact with other smaller galaxies,” Dr Tsukui said. “Both possibilities would bombard the galaxy with new star-forming fuel.

“Additionally, our study revealed a bar-like structure in the disk. Galactic bars can disrupt gas and transport it toward 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 today through a telescope are a throwback to the galaxy’s beginnings, when the universe was only 10% of its current age.

“Early galaxies have been found to form stars at a much faster rate than modern galaxies. This is true for BRI 1335-0417, which, despite having a mass similar to that of our Milky Way, forms stars stars at a rate a few hundred times faster.” said Associate Professor Emily Wisnioski, co-author.

“We wanted to understand how gas is supplied to keep up with this rapid rate of star formation.

“Spiral structures are rare in the early universe, and exactly how they form also remains unknown. This study also gives us crucial information about the most likely scenarios.

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