Astronomers discovered a 99.99 percent galaxy of dark matter. This is an absolute record among similar discoveries, and, as scientists note, observation of the galaxy will allow us to expand our knowledge of the properties of dark matter, which, as expected, accounts for up to 27 percent of the volume of the entire Universe.
Discovered galaxy, called the Dragonfly 44, is 300 million light years from us. It possesses the same mass with the Milky Way, but at the same time it has a hundred times less stars. Since there are few stars in it, therefore, its brightness is so low that they could not see the galaxy for decades. It should be noted that this is not the only galaxy, which is almost entirely composed of dark matter. Most dwarf galaxies may also have similar characteristics, but this is the first time scientists have come across such a volume of dark matter in one place.
Astronomers found the Dragonfly 44 galaxy (along with several others) as early as 2014 when, with the help of the Hawaiian Observatory of Keck, they observed the galactic region called the Coma Cluster. Scientists were immediately interested in how this galaxy still remains a single whole, since the total mass of its stars would not be enough for this. There were two options: either the stars in it are attracted to each other by dark matter, or the galaxy has an extremely unstable structure. The correct answer to this question, scientists have found quite recently.
In a recent article in the Astrophysical Journal Letters, the researchers shared details on how they, thanks to the power of huge telescopes, observed the speed of stars in the Dragonfly 44 galaxy for six days. The speed here really plays a key role. The faster the stars rotate, the greater the mass the galaxy must possess in order to keep these stars together.
According to the lead author of the study, Peter van Dokkum, the calculated speed (about 50 kilometers per second) may indicate that there is much more mass in the galaxy than all the stars put together in it.
“Stars in the Dragonfly 44 galaxy are moving very fast. Therefore, a certain paradox arose in front of us that was solved by the Keck Observatory telescopes. With the help of them, we were able to calculate that the total mass of the galaxy is much higher than the total mass of the stars it contains. ”
This discovery suggests that everything else that is contained in this galaxy may fall on dark matter. Its share here is 99.99 percent, which is even greater than that of one of the galaxies in the Virgo Cluster, 99.96 percent of the mass of which also falls on dark matter.
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