Astronomers have discovered a galaxy rotating since the early days of the universe

(ORDO NEWS) — A team of astronomers using the ALMA telescope has discovered a slowly rotating galaxy in the early universe. This galaxy is the youngest ever discovered with a measured rotation and is much slower than modern galaxies.

All galaxies rotate, usually at incredible speeds. For example, the speed of rotation of the Milky Way galaxy is more than 200 kilometers per second.

But astronomers don’t yet understand how galaxies achieve such speeds. The only way to know this is to measure galaxies throughout cosmic time, creating a map of galactic evolution.

Recently, a team of astronomers from Waseda University in Tokyo used the ALMA (Atacama Large Millimeter/submillimeter Array) in Chile to observe an extremely distant galaxy. This galaxy, MACS1149-JD1, is so far away that it is usually too faint to see.

But the light from this galaxy passes through a giant cluster of galaxies, and the gravitational lensing from this cluster magnifies MACS1149-JD1. Astronomers can use this magnification to see the galaxy.

Measuring the rotation of a galaxy

MACS1149-JD1 existed when the universe was only 500 million years old, making it one of the youngest known galaxies. A team of researchers used ALMA to study O III, or doubly ionized oxygen, in the galaxy’s disk.

They then developed a model for the size and rotational speed of the galaxy’s disk to compare it to observations.

They reported their results in an article recently published in The Astrophysical Journal Letters.

The team found that MACS1149-JD1 is only 3,000 light-years across. This is much smaller than the Milky Way galaxy, which is over 100,000 light-years across.

They also found that MACS1149-JD1 is spinning at just 50 kilometers per second, less than a quarter of the Milky Way’s rotational speed.

“The rotation rate of JD1 is much slower than that of later epoch galaxies and our [Milky Way] galaxy, and it is likely that JD1 is in its early stages of rotational development,” says Akio K. Inoue, co-author of the paper, also from Waseda University. .

These results suggest that galaxies start small and rotate slowly. Then, over billions of years, they accumulate more matter and increase their rotation rate.”

The team hopes to use the James Webb Space Telescope to conduct further research on the rotational speed of galaxies in space time.


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