astronomer using Atacama Large Millimeter/Submillimeter Array ALMA observed disk bending waves in BRI 1335-0417, the oldest known spiral galaxy, more than 12 billion years old. This unprecedented observation reveals the galaxy’s dynamic growth pattern, showing the motion of a vertically oscillating disk similar to ripples in a pond. This study is the first time such a phenomenon has been detected in an early galaxy.
This simulation shows how the galactic disk is disturbed and seismic ripples propagate throughout the disk. Image credit: Brand-Hawthorne & Tepper-Garcia, University of Sydney.
Bar structures play an important role in driving galaxy evolution and forming disk structures.
In galaxies, axisymmetric stellar bars exert a gravitational torque on the gas, driving it toward the galactic center and forming concentrated stellar structures such as bulges and core disks.
This process may also promote the accretion of gas onto black holes, which are observed as active galactic nuclei.
Bars can also cause radial migration of gas and stars, which is essential for explaining the stellar kinematics observed in galaxies similar to the Milky Way.
“Thanks to a cutting-edge telescope called ALMA, we have been able to observe the ancient galaxy BRI 1335-0417 in greater detail,” said lead author Dr Takafumi Tsukui, an astronomer at the Australian National University.
“In particular, we were interested in how gas moves within and across galaxies.”
“Gas is a key component for star formation and provides important clues about how galaxies actually drive star formation.”
In this case, Dr. Tsukui and his colleagues were not only able to capture the movement of gas around BRI 1335-0417, but also revealed the formation of seismic waves, a first for this type of early galaxy.
The galaxy’s disk moves similar to the ripples in a pond after a stone is thrown into it.
ALMA detected emission from carbon ions in the galaxy BRI 1335-0417. Image credit: ALMA / ESO / NAOJ / NRAO / T. Tsukui & S. Iguchi, doi: 10.1126/science.abe9680.
“The vertical oscillatory motion of the disk is due to external factors, such as new gas flowing into the galaxy or contact with other small galaxies,” Tsukui said.
“Both possibilities would bombard the galaxy with new fuel for star formation.”
“Furthermore, our study revealed rod-like structures within the disk.”
“The galactic rods can destroy gas and transport it towards the center of the galaxy.”
“The bar discovered at BRI 1335-0417 is the most remote known structure of its kind.”
“Taken together, these results point to the dynamic growth of young galaxies.”
“We know that early galaxies formed stars at much faster rates than modern galaxies,” said co-author Dr Emily Wisnioski, also from the Australian National University.
“This is also true for BRI 1335-0417, which has a similar mass to our Milky Way galaxy but forms stars hundreds of times faster.”
“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 remains unknown.”
“This study also provides important information about the most likely scenario.”
“While it is impossible to directly observe the evolution of galaxies, our observations only provide snapshots, so computer simulations can help piece together the story.”
of findings will appear in Royal Astronomical Society Monthly Notices.
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Takafumi Tsukui other. 2024. Disk bending waves detected in a barred spiral galaxy at redshift 4.4. MNRAS 527 (3): 8941-8949; doi: 10.1093/mnras/stad3588
Source: www.sci.news
