Astronomers capture the most distant galaxy rotations ever recorded

Astronomers have discovered the most distant galaxy rotation ever observed, implying an early stage in the development of rotational motions.

The galaxies first appeared after the Big Bang. These galaxies are moving away from us as the universe expands. As a result, their emissions are red-shifted (shifted to longer wavelengths).

It is possible to characterize the “motion” within galaxies and their distance by analyzing these redshifts. Waseda University In the new study, astronomers have discovered a likely rotational motion of such a distant galaxy.

Astronomers are able to identify increasingly distant galaxies as telescopes have become more sophisticated and powerful. These are some of the first galaxies to form in our universe, and as the universe expanded, they started pulling away from us. In reality, the greater the distance between the galaxies, the faster it tends to move away from us.

Researchers can estimate how fast a galaxy is moving, and thus when it formed, by observing how “red-shifted” its emission appears. This is similar to the “Doppler effect,” where moving objects emit light that appears to the observer to be displaced to longer wavelengths (hence the term “redshift”).

The Atacama Large Millimeter/submillimeter Array (ALMA) telescope, located in Chile’s Atacama Desert, is particularly suited to observe such redshifts in galaxy emissions.

Recently, a team of international researchers witnessed red-shifted emissions from a distant galaxy, MACS1149-JD1 (hereafter JD1), leading them to some fascinating conclusions.

The team of researchers includes Professor Akio Inoue and graduate student Tsuyoshi Tokuoka from Waseda University, Japan, Dr. Takuya Hashimoto of the University of Tsukuba, Japan, and Professor Richard S. Ellis of University College London, and Dr. Nicolas Laporte, a research fellow at the University of Cambridge, UK.

In addition to finding high redshift, namely very distant, galaxies, studying their internal motion of gas and stars motivates understanding the process of galaxy formation in the earliest possible universe.†

Richard S. Ellis, professor, University College London

The findings of their research have been published in The astrophysical diary letters†

The formation of a galaxy begins with the formation of gas and continues with the formation of stars from that gas. The star formation progresses from the center outward, forming a galactic disk and giving the galaxy its distinctive shape.

Newer stars form in the rotating disk as star formation continues, while older stars remain in the center. The phase of the galaxy’s evolution can be investigated by analyzing the age of stellar objects and the movement of stars and gas in the galaxy.

Over two months, the astronomers successfully measured small differences in the “redshift” from position to position within the galaxy and found that JD1 met the criterion for a galaxy dominated by rotation.

They then modeled the galaxy as a rotating disk and found that it accurately reproduced the observations. The calculated rotational speed was about 50 kilometers per second, compared to the rotational speed of the Milky Way disk of 220 kilometers per second. The group also evaluated the diameter of JD1 at 3,000 light-years, which is much smaller than the Milky Way’s diameter at 100,000 light-years.

The significance of their discovery is that JD1 is by far the most remote and thus earliest source yet found containing a rotating disk of gas and stars. Together with measurements of nearby systems in the scientific literature, the group was able to track the gradual evolution of rotating galaxies over more than 95% of our cosmic history.

In addition, the mass estimated from the galaxy’s rotational speed matched the stellar mass previously estimated from the galaxy’s spectral signature and was mainly derived from “mature” stars formed about 300 million years ago. .

†This shows that the stellar population in JD1 formed in an even earlier epoch of the cosmic ageHashimoto says.

†The rotational speed of JD1 is much slower than that found in galaxies in later epochs and our Milky Way and it is likely that JD1 is in an early stage of developing rotational motion‘ says Inoue.

Astronomers plan to use the recently launched James Webb Space Telescope to find the location of young and older stars in the galaxy to confirm and improve their galaxy formation conditions.

Magazine reference:

Tokuoka, T., et al† (2022) Possible systematic rotation in the adult stellar population of az = 9.1 Galaxy. The astrophysical diary letters† doi.org/10.3847/2041-8213/ac7447†

Source: https://www.waseda.jp/top/en/