Using Bright Streams to Learn about Dark Matter
Ordinary matter such as atoms make up only about 15% of all the matter in the universe. The other 85% is “dark matter” that is invisible but important enough to hold our galaxy, the Milky Way, together so it doesn’t break apart. What is dark matter? For decades astronomers have been thinking of ideas and trying to test these ideas by observations. One popular theory called “cold dark matter” has been widely successful in explaining dark matter in the universe as a whole, but it still needs to be tested inside our own galaxy. In this study, we show how computer simulations can help us use streams of stars in the galaxy to determine whether cold dark matter is the correct theory for dark matter.