Astronomers find Isolated Galaxy rich in dark matter

Using the FAST radio telescope, Chinese astronomers have discovered a new galaxy. It is isolated and has a relatively low stellar mass. Researchers believe that it is dominated by dark matter.

Morphology of a dark galaxy. Source: Xu et al, 2023

To date, FAST is the world’s largest radio telescope with a filled aperture. Its diameter is 500 meters, and it is actively used to study pulsars, the processes of formation and evolution of galaxies, as well as the search for dark matter.

During one of the observations, FAST discovered several new clouds of neutral atomic hydrogen in the local part of the Universe. One of them, designated FAST J0139+4328, attracted the attention of astronomers.

Measurements have shown that FAST J0139+4328 is located at a distance of 94 million light-years from the Milky Way. Further study showed that in fact it is not a gas cloud, but a disk galaxy, which is characterized by extremely low brightness. The mass of its stellar population is less than 690 thousand solar masses. At the same time, the galaxy is quite rich in gas, which mass has been estimated at 83 million solar masses.

According to the researchers, the ratio of the measured mass suggests that in FAST J0139+4328 dark matter dominates over ordinary (baryonic). Apparently, it has a rotating gas disk, but there are no stars in it. This, together with the fact that dark matter in FAST J0139+4328 dominates over ordinary matter, indicates that it is at the earliest stage of formation.

According to

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