A mysterious awakening of stars, propelled by a small galaxy that will collide with the Milky Way, may reveal the secrets of dark matter.
The path of the stars, located outside the star-studded spiral arms of the Milky Way’s central disk in a region called a galactic halo, is carried along with the cosmic flow of a dwarf galaxy into orbit around the Milky Way, according to a new map of the sky created by astronomers.
The galaxy, called the Large Magellanic Cloud (LMC), orbits about 130,000 light-years from The Earth and the movement of cosmic material behind it. At first glance, the LMC trail seems to consist only of stars, but researchers know that the stars are just right for the trip. They are hung in a far larger, completely invisible presence.
Connected: Distant! 1
Astronomers are interested in this wave in space because they believe it can be composed dark matter – the mysterious non-luminous substance that makes up most of the matter in the universe. Predictions say that dark matter, invisible and interacting with matter that we can only see by gravity, must be everywhere in the galactic halo.
“We think this awakening is made up of dark matter and it carries stars with it, which is the way we can find it,” said study co-author Nicholas Garavito-Camargo, a doctoral student at the University of Arizona. said in a statement.
The gravitational influence of dark matter can be observed throughout the universe: This is the lifeblood of our galaxy, which sticks stars and planets together so that it does not fly away as the galaxy rotates. Still, what exactly is dark matter or how it behaves remains one of the greatest mysteries of astronomy. The researchers hope that by studying the awakening, they will be able to study the dark matter that they believe makes up most of it.
If the stars of the awakening are like leaves floating on a pond of dark matter, the way the leaves are disturbed by a boat (in this case LMC) can tell us a lot about the pond itself.
“You can imagine waking up behind a boat would be different if the boat was sailing through water or honey,” said lead author Charlie Conroy, a professor of astronomy at Harvard University. “In this case, the properties of the trace are determined by which theory of dark matter we apply.”
The group uses its new map and trail position to confirm a theoretical model created by another group of researchers about how dark matter should be distributed in the galactic halo; tests are now underway to see which of the theories about dark matter best fits the shape and location of the awakening.
The map, made with data from NASA’s telescopes and the European Space Agency (ESA), also provides some vital insights into the violent future of our home galaxy. As the LMC orbits the Milky Way, the gravitational tug of dark matter in the galactic halo of the Milky Way slows it down, sending the LMC into smaller and smaller orbits. The LMC will continue to roll closer to the Milky Way until the two collide in about 2 billion years.
The merger of two galaxies is a surprisingly common event throughout the universe. The Milky Way probably merged with a small galaxy 8 billion years ago, and galaxy mergers are a key reason for the growth of all large galaxies.
“This robbery of energy in a smaller galaxy is not only why the LMC merges with the Milky Way, but also why all galaxy mergers occur,” said study co-author Rohan Naidu, a Harvard graduate student. “The awakening in our map is really pure confirmation that our basic picture of how galaxies merge is in place.”
The researchers published their findings on April 21 in the journal Nature.
Originally published in Live Science.