Astronomers have observed signs of rotation in a galaxy that existed only 500 million years after the Big Bang. It is the earliest galaxy ever discovered with a possible rotation. But the speed of rotation is slower than that of modern galaxies, indicating that the observed galaxy is still in the process of appearing to speed up. This is an important example for understanding the early evolution of galaxies.
Many galaxies in the modern universe, including our own Milky Way, revolve around a central region. When and how galaxies begin to spin is an important question in astronomy because it can affect the environment where stars, planets, and possibly even life-forms would later develop.
A team led by Tsuyoshi Tokuoka at Waseda University in Tokyo used ALMA (Atacama Large Millimeter/submillimeter Array) to observe the galaxy known as MACS1149-JD1, or JD1, over a period of two months. is for. JD1 existed in the early universe, only 500 million years after the Big Bang. By fitting a model to their observations, the team found that a small, slowly rotating galaxy best suited the data. The model indicates that JD1 is 3,000 light-years, compared to 100,000 light-years for the Milky Way; And its rotation speed is only 50 kilometers per second, compared to 220 kilometers per second for the Milky Way.
“JD1’s rotation speed is much slower than those found in galaxies in later epochs and ours” [Milky Way] Galaxy and it is likely that JD1 is in the early stages of developing a rotational motion,” said Akio K. Inoue, a co-author of the paper, also at Waseda University, says. With the recently launched James Webb Space Telescope, the team now plans to investigate JD1’s structure in more detail in order to refine their scenario for its formation.
These results emerged as those of Tokuoka et al. “Probable systematic rotation in mature stellar populations of the AZ=9.1 Galaxy” in Astrophysical Journal Letters.