Black holes are massive, strange and incredibly powerful astronomical objects. Scientists know that supermassive black holes reside in the centers of most galaxies.
And they understand how certain stars form the comparatively smaller stellar mass black holes once they reach the end of their life. Understanding how the smaller stellar mass black holes could form the supermassive black holes helps astronomers learn about how the universe grows and evolves.
But there’s an open question in black hole research: What about black holes with masses in between? These are much harder to find than their stellar and supermassive peers, in size range of a few hundred to a few hundred thousand times the mass of the Sun.
We’re a team of astronomers who are searching for these in-between black holes, called intermediate black holes. In a new paper, two of us (Krystal and Karan) teamed up with a group of researchers, including postdoctoral researcher Anjali Yelikar, to look at ripples in space-time to spot a few of these elusive black holes merging.
Take me out to the (gravitational wave) ball game
To gain an intuitive idea of how scientists detect stellar mass black holes, imagine you are at a baseball game where you’re sitting directly behind a big concrete column and can’t see the diamond. Even worse, the crowd is deafeningly loud, so it is also nearly impossible to see or hear the game.
But you’re a scientist, so you take out a high-quality microphone and your computer and write a computer algorithm that can take audio data and separate the crowd’s noise from the “thunk” of a bat hitting a ball.
You start recording, and, with enough practice and updates to your hardware and software, you can begin following the game, getting a sense of when a ball is hit, what direction it goes, when it hits a glove, where runners’ feet pound into the dirt and more.
Admittedly, this is a challenging way to watch a baseball game. But unlike baseball, when observing the universe, sometimes the challenging way is all we have.
This principle of recording sound and using computer algorithms to isolate certain sound waves to determine what they are and where they are coming from is similar to how astronomers like us study gravitational waves. Gravitational waves are ripples in space-time that allow us to observe objects such as black holes.
Now imagine implementing a different sound algorithm, testing it over several innings of the game and finding a particular hit that no legal combination of bats and balls could have produced. Imagine the data was suggesting that the ball was bigger and heavier than a legal baseball could be. If our paper was about a baseball game instead of gravitational waves, that’s what we would have found.
Listening for gravitational waves
While the baseball recording setup is designed specifically to hear the sounds of a baseball game, scientists use a specialized observatory called the Laser Interferometer…
