Astronomers have discovered a galaxy in which there are almost no dark matter
About 65 million light-years away, is the galaxy NGC 1052-DF2. It has a very interesting feature, truly puzzled scientists. The fact that this galaxy is almost no dark matter. About his discovery, researchers have shared in the journal Nature.
Scientists have never seen dark matter directly because it emits electromagnetic radiation and does not directly interact with them. Conclusions of its existence they have made on the basis of numerous observations of the indirect signs of how it exerts its effects on ordinary matter. According to these observations, it was found that dark matter can account for up to 27 weight percent of the whole universe.
Researchers believe that dark matter can explain the issue of hidden mass in the Universe, and as a result of gravity, which makes it possible to hold the astrophysical objects with each other. Dark matter, according to scientists, is taking an active part in the formation of galaxies - dense accumulations of dark matter through its gravity attracts normal matter in the form of gas and dust, from which eventually form stars, planets and other objects. Typically, each galaxy in the universe (at least of the detected) contains much more invisible dark matter than conventional visible. However, with the galaxy NGC1052-DF2 all turned out quite differently. It the scientists "discovered" the presence of a 1/400 share of dark mother from its expected level.
"The discovery of the galaxy without dark matter was very unexpected surprise for us. For decades we thought that galaxies begin their lives in the form of a cluster of dark matter, which gradually gets gas where stars are born and shaped sleeves, spirals like the Milky Way. NGC1052-DF2 casts doubt on all these ideas, "- said Pieter van Dokkum of Yale University.
A further study of the galaxy NGC1052-DF2 shown that its uniqueness lies not only in the amount of dark matter. It turned out to not be attributed to one or another class of galaxies. It does not meet the same characteristics of spiral galaxies, which tend to the presence of the dense central region of the spiral arms and the disc-shaped. It is also not suitable for determination of elliptical galaxies in the centers of which are, as a rule, have a supermassive black hole. Instead NGC1052-DF2 looks completely empty.
"NGC1052-DF2 looks as if someone has taken a typical galaxy, and left of it only globular clusters and groups of stars on its outskirts, and threw out the rest. It is so low, that through it you can see other galaxies that are behind it. Theory that predicts the existence of such facilities do not exist. This galaxy is still a complete mystery to us, and we can not explain any of it slashes. As it emerged, it is absolutely unclear ", - says Pieter van Dokkum.
In further studies of the galaxy NGC1052-DF2 scientists will try to figure out her age.
"At the moment we only know that she is more than 10 billion years. Does she appeared 10 billion years ago, or 13, that is, soon after the Big Bang - we can not say, "- added Dokkum.
If it turns out that she was more than 13 billion years, it will be also one of the oldest ever discovered by researchers.