When measuring the speed of stars circling around a nearby dwarf galaxy, astronomers realized that there could be huge reserves of dark matter there.
Such a guess arose among astronomers when they tried to measure the mass of Triangle II - the neighboring dwarf galaxy. Using 6 stars as markers, they measured their speed around the center of the galaxy. Scientists know that in the galaxy of Triangle II contains about 1, 000 stars and that this galaxy has an average weight by space standards, but appearance can be deceiving. They discovered a surprisingly dense galaxy, which seems to be filled with dark matter.
"The total mass was very large, much larger than the total mass of the stars - this means that tons of dense packed dark matter are located there," said astronomer Evan Kirby of the California Institute of Technology in Pasadena. "The ratio of dark matter to visible matter is one of the highest of all the galaxies we know. After I made the measurements, I just thought - wow!". After calculating the speed of the stars inside the Triangle II galaxy, thanks to the Keck Observatory located on Mauna Kea, Hawaii, the Kirby team discovered that their high speed was due to some kind of additional mass. Moreover, they realized that this tiny galaxy may have the highest concentration of dark matter.
So what happens there? According to one theory, for some reason Triangle II can be home to a dense cloud of interacting massive particles or wimps. Wimps are hypothetical particles that carry mass, but do not interact with ordinary matter. These are ghostly particles that have the force of gravity and cannot be seen. However, wimps can destroy each other during a collision, so if something like this happens in Triangle II, we should observe an excess of gamma radiation emitted from the galaxy.
Triangle II is also known as the “dead galaxy”. There are practically no gases for star formation in it and very dim stars (in fact, the reason why the Kirby team used only 6 stars is that this galaxy only 6 stars have sufficient brightness). Thus, a dwarf galaxy should not produce large amounts of high-energy radiation, such as gamma rays. So if we find enough gamma rays there, it will be like a “smoking gun” in the WIMP annihilation. However, other dimensions indicate that stars outside Triangle II are moving faster than those used for calculations by the Kirby team. If so, then the star speed may be a sign that the gravitational field of our galaxy breaks Tregolnik II apart.
"My next steps are to calculate the speed of movement of external stars," said Kirby. "If it turns out that these outer stars move no faster than the inner ones, then the galaxy may be in dynamic equilibrium. This would make it the best candidate for detecting dark matter."
