A group of astronomers have used the ALMA telescope to find a slowly-rotating galaxy in the early universe. That galaxy is the youngest ever discovered with a measured rotation, and its much slower than contemporary galaxies.
All galaxies turn, normally at unbelievable speeds. For example, the Milky Way galaxy has a rotation speed of over 200 kilometers per second. Astronomers do not yet comprehend how galaxies build up to these speeds. The only method to tell is through measurements of galaxies throughout cosmic time, developing a map of galactic advancement.
Recently a group of astronomers based at Waseda University in Tokyo used ALMA (the Atacama Large Millimeter/submillimeter Array) in Chile to observe an exceptionally far-off galaxy. This galaxy, MACS1149-JD1, is so far away that its typically far too dim to be observed. The light from that galaxy passes through a huge galaxy cluster, and the gravitational lensing from that cluster magnifies MACS1149-JD1. Astronomers can utilize this zoom to see the galaxy.
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Determining galaxy rotation
MACS1149-JD1 existed when deep space was only 500 million years of ages, making it among the youngest recognized galaxies. The group used ALMA to study O III, or doubly-ionized oxygen, in the disk of the galaxy. They then established a design of the size and rotation speed of the disk of the galaxy to compare versus observations. They reported their results in a paper just recently appearing in The Astrophysical Journal Letters.
The team discovered that MACS1149-JD1 is just 3,000 light-years throughout. That is far smaller sized than the Milky Way galaxy, which is over 100,000 light-years across. They also discovered that MACS1149-JD1 rotates at only 50 kilometers per 2nd, which is less than a quarter of the Milky Ways rotation speed.
“The rotation speed of JD1 is much slower than those discovered in galaxies in later epochs and our [Galaxy] Galaxy and it is likely that JD1 is at an initial stage of developing a rotational motion,” says Akio K. Inoue, a co-author of the paper, likewise at Waseda University.
These results recommend that galaxies start little and rotate gradually. Over the course of billions of years, they accumulate more matter and increase their rotation rate. The team intends to utilize the James Webb Space Telescope to perform more research studies of galaxy rotation rates over cosmic time.
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The Milky Way galaxy has a rotation speed of over 200 kilometers per second. Recently a team of astronomers based at Waseda University in Tokyo utilized ALMA (the Atacama Large Millimeter/submillimeter Array) in Chile to observe an extremely far-off galaxy. The light from that galaxy passes through a giant galaxy cluster, and the gravitational lensing from that cluster magnifies MACS1149-JD1. They then established a model of the size and rotation speed of the disk of the galaxy to compare against observations. The team hopes to use the James Webb Space Telescope to conduct more studies of galaxy rotation rates over cosmic time.
