The Atacama Large Millimeter/submillimeter Array (ALMA) has detected the oldest spiral galaxy found to date. Named BRI 1335-0417, researchers who were studying the data collected by ALMA discovered the galaxy with a spiral morphology that formed just 1.4 billion years after the Big Bang. This is providing very important information to scientists attempting to solve the ancient mystery of how and when spiral galaxies were created.
While spiral galaxies make up about 70% of the total amount – including our own Milky Way Galaxy – previous studies have revealed that spiral ones weren’t as common the further back scientists have dug into the history of the universe.
As for how this galaxy got its spiral shape, the researchers have several theories including one that suggests BRI 1335-0417 may have collided with a smaller galaxy.
Takafumi Tsukui, who is a graduate student at SOKENDAI, described the significance of this discovery, “I was excited because I had never seen such clear evidence of a rotating disk, spiral structure, and centralized mass structure in a distant galaxy in any previous literature.” “The quality of the ALMA data was so good that I was able to see so much detail that I thought it was a nearby galaxy.”
The BRI 1335-0417 galaxy has quite a bit of dust that blocks off the starlight which makes it very hard for researchers to study it in great detail. Thankfully, ALMA can find radio emissions from carbon ions that are within the galaxy.
The spiral structure of the galaxy measures about 15,000 light-years outwards from its center. It is believed that the BRI 1335-0417’s entire mass of its stars and interstellar matter is about the same as our own galaxy. Tsukui commented on its large size by noting, “As BRI 1335-0417 is a very distant object, we might not be able to see the true edge of the galaxy in this observation.” “For a galaxy that existed in the early Universe, BRI 1335-0417 was a giant.”
Regarding the future of BRI 1335-0417, nobody knows for sure what will happen. It is thought that galaxies that have big amounts of dust and form stars in the ancient Universe are the ancestors of today’s large elliptical galaxies. If this is correct, that would mean that BRI 1335-0417 could change from a disk galaxy to an elliptical one at some point in the future. On the other hand, it could possibly stay as a spiral galaxy. Nevertheless, it will provide scientists with very important clues regarding the shape evolution of ancient galaxies. (A photo of BRI 1335-0417 can be seen here.)
The study was published in the journal Science where it can be read in full.