Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have observed a disk bending wave in BRI 1335-0417, the oldest known spiral galaxy at over 12 billion years old. This unprecedented observation reveals the galaxy’s dynamic growth patterns, showcasing a vertically oscillating disk movement similar to ripples on a pond. The study marks the first time such phenomena have been detected in an early galaxy.
Bar structure plays a crucial role in driving galaxy evolution and shaping disk structure.
In galaxies an axisymmetric stellar bar exerts gravitational torque on the gas, driving it towards the galactic center and forming a centralized stellar structure such as a bulge and nuclear disk.
This process may also promote gas accretion onto the black hole observed as active galactic nuclei.
Bars can also drive radial migration of gas and stars, which is essential for explaining the observed stellar kinematics in Milky Way-like galaxies.
“A state-of-the-art telescope called ALMA allowed them to look at the ancient galaxy BRI 1335-0417 in much greater detail,” said lead author Dr. Takafumi Tsukui, an astronomer at Australian National University.
“Specifically, we were interested in how gas was moving into and throughout the galaxy.”
“Gas is a key ingredient for forming stars and can give us important clues about how a galaxy is actually fuelling its star formation.”
In this case, Dr. Tsukui and colleagues were able to not only capture the motion of the gas around BRI 1335-0417, but also reveal a seismic wave forming — a first in this type of early galaxy.
The galaxy’s disk moves in a way not dissimilar to ripples spreading on a pond after a stone is thrown in.
“The vertically oscillating motion of the disk is due to an external source, either from new gas streaming into the galaxy or by coming into contact with other smaller galaxies,” Dr. Tsukui said.
“Both possibilities would bombard the galaxy with new fuel for star…
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