As far as galaxies go, our Milky Way is a relatively quiet place. Sure, there are star-forming regions that are active right now within our galactic plane, giving birth to thousands of new stars at once over timescales of a few million years, including relatively nearby in places like the Orion Nebula. But most of our galaxy isn’t forming stars, just a few select locations along our spiral arms. In terms of the overall star-formation rate, we form less than one solar mass’s worth of new stars with each year that passes. Even our galactic center is relatively quiet, with just the occasional “blip” in X-ray light emanating from our own supermassive black hole. Across the Universe, however, there are many galaxies that are much more active than we are. This includes: galaxies that are undergoing intense episodes of star-formation across large regions, galaxies where gas in the central regions are rapidly forming new stars all at once, and galaxies whose central nucleus is actively feeding right now, creating copious high-energy signatures that our own …