According to the results of a new study, our galaxy consists of an atrium of dark matter that surrounds the disk of the Milky Way. Remember that dark matter is the most mysterious substance in the universe that cannot be seen and that only occurs during the gravitational interaction of space objects. Recently, Durham University astronomers calculated the true size of our galaxy by examining the attraction of smaller neighboring galaxies. The disk of the Milky Way consists of stars, black holes, planets and other celestial objects and extends over 260,000 light years. At the same time, the rest of the Milky Way consists of an invisible "atrium of dark matter" – a huge ball of dark matter that envelops the galactic disk. After creating a detailed 3D map of dark matter around the supermassive black hole of Sagittarius A *, the scientists found that the atrium of dark matter extends over 950,000 light years, as in other galaxies of the same size.
A halo of dark matter is a hypothetical component of galaxies that surrounds a galactic disk and extends far beyond the boundaries of a visible galaxy.
Mysteries of the Milky Way
After observing the unusually fast speed of the stars on the outer edge of our galaxy's disk, astronomers discovered that the Milky Way is surrounded by a sphere of dark matter. Keep in mind that dark matter can only be detected by the influence of its gravity on other objects. However, dark matter cannot be seen because it does not interact with photons – light particles. A group of researchers led by astrophysicist Alice Dyson from Durham University decided to find out how far this sphere of invisible matter actually extends from the edge of the Milky Way. "In many studies of the Milky Way halo, its outer boundary is a fundamental limitation," the study authors write.
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In their work, the scientists used data on the interaction of dark matter with surrounding objects. As a result, they managed to create a virtual map of a local group of galaxies – a series of galaxies approximately 9.8 million light-years across, including the Milky Way and our closest galactic neighbor, the Andromeda Galaxy. With this simulation, we could see what the dark matter halo of the Milky Way would look like and how it would interact with other objects. It turned out that outside the dark matter halo, the radial velocity – the orbital velocity of objects moving in the galaxy – decreases significantly.
Scientists compared the simulated data with real observations from nearby dwarf galaxies. The fact is that astronomers cannot observe the entire Milky Way since we are in the galaxy. Observations of other galaxies in the local group coincided with the simulation and showed a sudden drop in radial velocity, which allowed us to calculate the diameter of our galaxy. In dwarf galaxies, this limit is 950,000 light years. The study's authors believe that they can measure the edges of the Milky Way and nearby galaxies of the same mass more accurately in the future. The work is published in the Royal Astronomical Society's Monthly Notices. You can familiarize yourself with the work on the arXiv preprint server.
What is dark matter?
Dark matter makes up about 27% of the universe. It is invisible because it does not reflect light.
Despite the fact that dark energy cannot be seen directly through telescopes, astronomers know that it is there due to the gravitational effect it exerts on visible matter.
Dark matter is believed to be the gravitational glue that holds galaxies together, while only 5% of the universe is made up of known material such as atoms and subatomic particles.
In general, our website offers excellent dark matter material. This mysterious form of matter, which literally “holds” galaxies together, has been studied by scientists for many years, and in our opinion everyone should know about their successes.