We know that throughout our galaxy, the Milky Way, there are about 100 million black holes, these mysterious gravitational objects that never let out the particles they attract, including light. By definition, as their name implies, they are dark bodies that can go unnoticed by our detection instruments, except when feeding.
Do black holes feed? Not only do they feed, but they are “terribly noisy” when they do. When a black hole attracts stellar matter, it can emit bursts of X-rays that bounce and echo off the gas they consume. And although technically this type of radiation is not audible, a team of researchers at MIT, in collaboration with members of the departments of education and music, converted the emission of waves into sounds that we can hear.
And why do we want to hear it? Listening to a black hole is quite amazing, but it is true that it cannot be considered a scientific goal of the first order. In fact, this is a “side project” of a much more ambitious investigation published in The Astrophysical Journal, on the evolution of black holes.
To do this, astronomers used a tool called the “Reverberation Machine.” They analyzed data taken by NASA’s Neutron Star Interior Composition Explorer (NICER) aboard the ISS to find binary black holes and study their echoes. They located eight new systems that produced this type of echo.
But what is an echo? It is a phenomenon by which a wave is reflected and emitted again. The echoes represent the time delays between two types of X-rays. On the one hand we have those of the light emitted directly from the corona and the light from the corona that bounces off the accretion disk.
The time a telescope receives light from the corona, compared to when it receives X-ray echoes, has been used to calculate the distance between the corona and the accretion disk.
The researchers used these echoes to map the surroundings of gravitational objects in the same way that bats use sound echoes to navigate their surroundings. Without this breakthrough, the team would not have been able to build the picture of how a black hole evolves.
The researchers used these echoes to map the surroundings of gravitational objects in the same way that bats use sound echoes to navigate their surroundings. Without this breakthrough, the team would not have been able to build the picture of how a black hole evolves.
The hidden evolution of black holes. By comparing the echoes, the team found that black holes go through several states: the “hard” state (where large amounts of energy are emitted) and the soft state. Scientists discovered the keys to the transition between some states and others,
According to Erin Kara, one of the MIT researchers, these findings could help explain how the largest supermassive black holes at the center of a galaxy can eject particles across vast cosmic scales to shape the formation of a galaxy. You may be right. However, today we will keep the most amazing part: the sound that a black hole makes when eating.
In Xataka | Hubble’s latest discovery: a black hole that creates stars instead of gobbling them
Image | NASA Goddard Space Flight Center
George is Digismak’s reported cum editor with 13 years of experience in Journalism