A group of astronomers have used the ALMA telescope to discover a slowly-rotating galaxy within the early Universe. That galaxy is the youngest ever discovered with a measured rotation, and it is a lot slower than present-day galaxies.
All galaxies rotate, normally at unimaginable speeds. For instance, the Milky Manner galaxy has a rotation pace of over 200 kilometers per second. However astronomers don’t but perceive how galaxies construct as much as these speeds. The one option to inform is thru measurements of galaxies all through cosmic time, build up a map of galactic evolution.
Not too long ago a group of astronomers primarily based at Waseda College in Tokyo used ALMA (the Atacama Massive Millimeter/submillimeter Array) in Chile to look at an especially distant galaxy. This galaxy, MACS1149-JD1, is so distant that it is usually far too dim to be noticed.
However the mild from that galaxy passes by an enormous galaxy cluster, and the gravitational lensing from that cluster magnifies MACS1149-JD1. Astronomers can use this magnification to see the galaxy.
Measuring galaxy rotation
MACS1149-JD1 existed when theUniverse was solely 500 million years outdated, making it among the many youngest recognized galaxies. The group used ALMA to review O III, or doubly-ionized oxygen, within the disk of the galaxy.
They then developed a mannequin of the dimensions and rotation pace of the disk of the galaxy to match in opposition to observations.
They reported their ends in a paper not too long ago showing in The Astrophysical Journal Letters.
The group discovered that MACS1149-JD1 is simply 3,000 light-years throughout. That’s far smaller than the Milky Manner galaxy, which is over 100,000 light-years throughout. Additionally they discovered that MACS1149-JD1 rotates at solely 50 kilometers per second, which is lower than 1 / 4 of the Milky Manner’s rotation pace.
“The rotation pace of JD1 is way slower than these present in galaxies in later epochs and our [Milky Way] Galaxy and it’s possible that JD1 is at an preliminary stage of growing a rotational movement,” says Akio Okay. Inoue, a co-author of the paper, additionally at Waseda College.
These outcomes recommend that galaxies begin out small and rotate slowly. Then, over the course of billions of years, they accumulate extra matter and improve their rotation fee.
The group hopes to make use of the James Webb House Telescope to conduct additional research of galaxy rotation charges over cosmic time.