Hear the frightening sounds of echoing black holes

Anatomy of a black hole explosion

The research team has developed an automated tool called the Echo Machine to search for echoes from black hole binaries in satellite data.

During their study, the researchers used the echo machine to look at data collected by NASA’s X-ray Telescope called the Neutron Star Interior Composition Explorer, or NICER, which is part of the International Space Station.

“We see a new echo in eight sources,” senior study author Jingye Wang, a graduate student at the Massachusetts Institute of Technology, in a statement. “The masses of black holes range from five to 15 times the mass of the Sun, and they are all in binary systems with ordinary, low-mass, Sun-like stars.”

After collecting the eight echoes, the researchers compared them to see how the black hole changes when it releases a wave of X-rays. A similar picture emerged for the eight binary systems.

When black holes pull material from a star orbiting it, they can release bright “jets” of particles that flow into space at nearly the speed of light. The research team notes that during this process, the black hole will emit a final high-energy flash before transitioning to a low-energy state.

When this latest explosion occurs, it could mean that the black hole’s highly energetic plasma ring (or corona) is releasing energetic particles before they disappear.

Astronomers can apply this discovery to supermassive black holes, which act as “engines” at the center of galaxies and can release particles that could shape the formation of galaxies.

“The role of black holes in the evolution of galaxies is a prominent question in modern astrophysics,” study author Irene Kara, associate professor of physics at MIT, said in a statement.

“Interestingly, black hole binaries appear to be supermassive black holes, so by understanding explosions in these small nearby systems, we can understand how similar explosions in supermassive black holes affect the galaxies in which they reside.”

Convert X-ray echo to sound

The echoes of these X-ray emissions could help astronomers locate black holes. It is no different from echolocation that bats use for navigation. Bats release calls that bounce off obstacles and return as echoes, and the length of the echo returns helps bats determine the distance of objects.

Black hole echoes are created by two types of X-ray light emitted from the corona, and astronomers can use the amount of time it takes a telescope to detect both types to track how the black hole changes as it devours material from a star.

Black hole echoes aren’t real sounds we can hear without some help, so Kara teamed up with Kyle Kane, a lecturer in the MIT Department of Materials Science and Engineering.And and Ian Condry, professor in the Department of Anthropology at MITAnd to convert them into sound waves.

The team tracked changes in X-ray echoes, identified time periods during transitions and traced commonalities in the evolution of each black hole burst.

The result looks like something out of a 1950s science fiction movie.

“We are in the beginnings of being able to use these echoes of light to reconstruct environments closer to the black hole,” Kara said. “We have now shown that these echoes are commonly observed, and we are able to examine the connections between a black hole’s disk, jet, and corona in a new way.”