Astronomers first noticed the strange behaviors of rotating galaxies almost 100 years ago, suggesting there’s an invisible dark matter hold them together with gravity. Or maybe we just don’t understand how gravity works at the largest scales. Observations are much better now, and astronomers have found examples of galaxies that almost entirely made of dark matter. Does this tell us anything?
In 2017, astronomers detected the gravitational waves and electromagnetic radiation from colliding neutron stars. This had been long theorized as one of the causes of a certain type of gamma-ray burst. By studying the event and its afterglow, astronomers have learned a tremendous amount about the formation of the heaviest elements in the Universe.
Last week we talked about rogue stars. This week we’re going to take things up a notch and talk about an even more extreme event. Rogue black holes. Astronomers recently discovered a supermassive black hole on an escape trajectory, leaving newly forming stars in its wake. It’s wonderful, terrible, nightmare fuel.
Most stars in the Milky Way are trapped in here with us, doomed to orbit around and around and around. But a few have found a way out, an escape into the freedom of intergalactic space. How do stars reach escape velocity, never to return?
