Researchers have found ripples resembling ponds in an old galaxy’s gaseous disk.
What created the ripples and what can we infer about the origin and evolution of the far-off galaxy from them? And in any case, what impact has it had on the galaxy’s primary function of star formation? The oldest known spiral galaxy is the subject of this discovery. It is known as BRI 1335-0417 and is more than 12 billion years old. It is significant to our understanding of the formation and evolution of galaxies since it is the oldest spiral known to science.
Scientists claim that the growth patterns of the galaxy are revealed by the ripples in the disk of BRI 1335-0417. The observations reveal a disk movement that oscillates vertically, resembling pond ripples. This is the first time that the ripples have been seen, and they may provide some insight into how stars arise in our galaxy.
The observations are a component of recent work that was released in the Royal Astronomical Society’s Monthly Notices. “Detecting a disc bending wave in a barred-spiral galaxy at redshift 4.4” is the title of the study. Dr. Takafumi Tsukui, a Postdoctoral Fellow at the Australian National University’s Research School of Astronomy and Astrophysics (RSAA), is the primary author.
Star formation at BRI 1335-0417 is characterized by a fast rate. In comparison to contemporary galaxies like the Milky Way, it creates stars far more often. It generates stars hundreds of times quicker than our galaxy, according to some observations. Compared to other galaxies, this one manages to move gas and convert it into stars more effectively.
The Atacama Large Millimetre/submillimetre Array, or ALMA, was used to make the observations that made the ripples visible. ALMA’s ability to observe gas and dust in particular is what allowed it to detect the ripples. According to the researchers, the ripples are proof of an outside force of some kind, such as interactions with a different galaxy or maybe approaching gas. Both of those factors have the potential to accelerate star formation, which may contribute to the rapid star creation observed in BRI 1335-0417.
But ALMA discovered evidence of a central bar in addition to ripples. Bars in spiral galaxies can stimulate star formation by directing gas from the arms into the core of the galaxy, where it fuels the genesis of new stars. Active galactic nuclei could likewise be explained by the same process.
“The bar, 3.3 +/- 0.2 kiloparsecs long in radius and bridging the previously identified two-armed spiral, is evident in both [C-II] and [far infrared] images, driving the galaxy’s rapid evolution by channelling gas towards the nucleus,” according to the study.
In spiral galaxies, bars are typical. According to one study, bars can be seen in more than 25% of spiral galaxies. The Andromeda galaxy, our nearest neighbor, and the Milky Way are both barred spiral galaxies. Spiral galaxies with barred spirals may eventually become plainer spirals if the bars are transient and eventually dissolve. Bars might exist for a maximum of two billion years. One possible explanation for their abundance could be that they are cyclical, always forming and decaying. According to some accepted astronomical theory, a galaxy’s evolution ends with the formation of a bar.
“Perhaps the creation of a bar represents the last significant step in a spiral galaxy’s evolution,” Spitzer Science Center’s Kartik Sheth stated in regard to study in 2008. It is believed that galaxies self-assemble through merging with other galaxies. The motion of bars is the only other spectacular way galaxies can change after they settle down.”
However, bars have never been discovered in a galaxy this early in the universe by scientists. It implies an alternative mechanism for the formation of bars. “The bar identified in [C-II] and [far infrared] images of the gas-rich disc galaxy suggests a new perspective of early bar formation in high redshift gas-rich galaxies – a gravitationally unstable gas-rich disc creating a star-forming gaseous bar, rather than a stellar bar emerging from a pre-existing stellar disc,” the authors write.
“This may explain the prevalent bar-like structures seen in FIR images of high-redshift submillimeter galaxies,” the authors write. Rethinking is being forced by the discovery of these ripples and the bar in this old galaxy. In a galaxy such as this one, the gas disk is normally steady; the ripples suggest that something has just occurred to the disk.
It is unknown if this was a collision with a huge gas cloud or with another galaxy. Nonetheless, the writers believe the conclusion to be reasonable. “It is natural to suppose that such an interaction would also activate the high star formation activity,” they state. There is no doubt among astronomers that galaxies form and change as a result of mergers with huge gas clouds and other galaxies. These results do not refute the hypothesis. However, the detection of discernible ripples provides researchers with an additional perspective on how it all operates.
