A team of MIT scientists is looking for echoes of black holes in an effort to shed light on regions of spacetime that remain largely a mystery to us. To see, black holes only show some semblance of activity when they feed on gas and dust from one of their orbiting stars. When they do, they emit bursts of X-rays that echo the consumed gas and illuminate their surroundings. This is what a black hole echo is. Although it’s technically an X-ray echo, the team worked with education and music specialists at MIT to turn the broadcast into audible sound waves which you can listen to below. .
For their new study, astronomers have developed an automated research tool called the “Reverberation Machine” to sift through data collected by NASA’s Neutron Interior Composition Explorer star, the X-ray telescope aboard the ISS. Their algorithm identified 26 binary black hole X-ray systems, which are systems with a star that is sometimes consumed by a black hole. Ten of them are close enough for the echoes to be observable, and eight were previously not known to emit echoes.
So what did the team discover by analyzing the echoes? They found that black holes initially go through a “hard” state upon feeding, in which they form a corona of high-energy photons and launch a jet of high-energy particles near the speed of light. This condition lasts for several weeks. After a final high-energy flash as the corona and jet die out, the black hole enters a low-energy “soft” state.
Scientists believe these findings may help explain how supermassive black holes at the center of galaxies can help shape their formation. As Erin Kara, assistant professor of physics at MIT, put it:
“The role of black holes in the evolution of galaxies is an open question in modern astrophysics. Interestingly, these black hole binaries appear to be supermassive ‘mini’ black holes, and thus understanding the explosions in these small nearby systems, we can understand how similar explosions in supermassive black holes affect the galaxies in which they reside.”