BRENT: Dark matter is elusive. Dark matter particles significantly outnumber regular matter particles, experts said, but the only way to detect its existence is by inferring its gravitational effects on galaxies.
Through this method, a scientist at the California Institute of Technology (Caltech) found that a dwarf galaxy at the edge of the Milky Way contains the highest concentration of dark matter that experts have ever seen–albeit not literally.
Caltech Astronomy Assistant Professor Evan Kirkby measured the mass of Triangulum II, a small and faint galaxy that is made up of only about 1,000 stars, by examining the velocity of six stars found in the galaxy’s center. This small galaxy is 117,000 light-years away from our planet
Kirkby said the galaxy’s six stars were the only ones luminous enough to be seen through the Keck telescope. He then inferred the gravitational force on the stars and calculated the mass of Triangulum II.
“The ratio of dark matter to luminous matter is the highest of any galaxy we know,” he explained. The total mass Kirkby measured was extremely greater than that of the sum of the galaxy’s stars. It implies that a ton of dark matter, which is densely-packed, is contributing to the galaxy’s total mass, he said.
