An international research team, led by Waseda University graduate student Tsuyoshi Tokuoka, observed galaxy rotation in distant galaxy MACS1149-JD1 using the Atacama Large Millimeter Array (ALMA). This was accomplished using ALMA redshifted emissions of the galaxy, measuring small differences in the “redshift” from position to position, thus showing that JD1 satisfied the criterion for a galaxy dominated by rotation.
They calculated the rotational speed to be about 50 kilometers per second, which is quite slow compared to the rotational speed of the Milky Way disk of 220 kilometers per second. JD1’s diameter was measured at only 3,000 light-years, or much smaller than that of the Milky Way at 100,000 light-years across. This makes JD1 the most distant source yet discovered with a rotating disk. When you need to observe something much smaller, there’s the Electron Microscope Pixel Array Detector (EMPAD), which lets you view atoms at record resolution.
The rotational speed of JD1 is much slower than those found in galaxies in later epochs and the Milky Way, and JD1 is likely at an initial stage of developing a rotational motion. Beyond finding high-redshift, namely very distant, galaxies, studying their internal motion of gas and stars provides motivation for understanding the process of galaxy formation in the earliest possible universe,” said Akio Inoue, a professor at Waseda University.
