Our galaxy’s heart is a gluttonous monster. Like the mythical Kammapa of the Sotho people of southern Africa, the Milky Way’s central, supermassive black hole has swallowed nearly everything around it, growing heftier and heftier the more it eats. And it’s not alone. Black holes weighing as much as thousands, millions or even billions of suns sit at the center of nearly all known massive galaxies.
For decades, scientists thought that was the only place they’d find such behemoths, because only massive galaxies had enough material to feed the monsters’ excessive appetites. But beginning about two decades ago, computer simulations of the earliest black holes started turning up oddities — big black holes that weren’t smack-dab where they were expected. These misfits must be nothing more than flukes, many scientists reasoned at the time, dismissing the results without a second thought.
But others weren’t so certain the oddballs should be cast off. If observations show that these unusual black holes exist in the nearby universe, these astrophysicists speculated, they could be untapped clues to the universe’s infancy and adolescence.
“We can, weirdly, [learn about] the super-beginning of the universe by looking at things really close to us,” says theoretical astrophysicist Jillian Bellovary of Queensborough Community College in New York City.
The notion remained just an idea for years. But now, the existence of these misfits isn’t so easy to ignore. Astronomers have turned up signs of a number of unexpectedly massive black holes in the universe’s tiniest galaxies, and surprisingly, some of those black holes don’t appear to sit at their galaxies’ centers. Even more intriguing, astronomers have spotted evidence of black holes wandering at their galaxies’ edges, and in rare cases, being kicked from their homes into intergalactic space.
Perhaps these black holes aren’t merely cosmic nonconformists but instead big players in the story of our universe. If so, they are a tool for probing one of the greatest mysteries in all of astrophysics — how the cosmic Kammapas we see today came to be.
“Without understanding what black holes are doing, you cannot understand galaxy evolution,” says Xiaohui Fan, a cosmologist at the University of Arizona in Tucson, making it impossible to explain the landscape of the universe. [Continue reading…]