Hearing the whirlwind noise of “black holes” for the first time
Astronomers listen for the first time to low-frequency gravitational waves
The background noise emanating from the whirlwind of giant black holes has finally been detected, after astronomers have sought to track it for a quarter of a century, and what made it possible to hear it for the first time is an unprecedented technique for detecting gravitational waves, which opens a “new window on the universe.”
These results are the result of a large-scale collaboration of the largest radio telescopes in the world that were able to capture this vibration of the universe “with clock accuracy”, which aroused the enthusiasm of the authors of the study published simultaneously in more than one scientific journal.
Gravitational waves, the existence of which was first indicated by Einstein in 1916 and were already observed a hundred years later, are small distortions in space-time, like ripples of water on the surface of a pond. These oscillations, which spread at the speed of light, are caused by violent cosmic events, such as the collision of two black holes.
It is noteworthy that its signals are very weak, although they are caused by huge phenomena. In 2015, the gravitational-wave detectors LIGO (USA) and VIRGO (Europe) revolutionized astrophysics by detecting the sub-second tremor caused by collisions between stellar black holes ten times the mass of the Sun.
To discover these waves, scientists used a new tool, which are pulsars from the Milky Way, and these stars are characterized by the fact that their mass is equivalent to between one and two suns, compressed into a ball with a diameter of about ten kilometers.
These very small stars revolve around themselves at a high speed of up to 700 revolutions per second, as explained by the researcher at the French National Center for Scientific Research, and this high-speed rotation results in magnetic radiation at the poles, similar to the rays of a beacon, that can be detected thanks to radio waves emitted from low frequencies.
