Milky Way's Dwarf Neighbor Is The 'Dark Lord'
Astronomers may have stumbled up on their playground to detect the elusive dark matter that exponentially eclipses visible matter but is yet to be spotted.
A dead dwarf galaxy called Triangulum II on the fringe of Milky Way has a mass that is much larger than the combined mass of all stars and visible matter in it. The difference is so large that scientists at Caltech believe that dark matter is aplenty and further observations in the galaxy could help detecting dark particles, UPI reports.
"The total mass I measured was much, much greater than the mass of the total number of stars-implying that there's a ton of densely packed dark matter contributing to the total mass. The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had made my measurements, I was just thinking-wow," Assistant Professor of Astronomy Evan Kirby said.
Theoretically, dark matter can be detected by signature gamma rays produced when two dark particles annihilate one another. However, visible matter also produces gamma rays making distinguishing between the two difficult. In a galaxy like Triangulum II, where processes like star formation, pulsars or other cosmic activity associated with visible matter is absent, activity of dark matter is more easily perceptible.
Before Kirby could start looking for dark matter, his findings have to be confirmed. An earlier study by researchers in France found that stars at Triangulum II's fringes are moving away faster than those at its center, most likely due to massive Milky Way's proximity. This could mean that Kirby may not have measured all of the visible matter.
"My next steps are to make measurements to confirm that other group's findings," Kirby says. "If it turns out that those outer stars aren't actually moving faster than the inner ones, then the galaxy could be in what's called dynamic equilibrium. That would make it the most excellent candidate for detecting dark matter with gamma rays."