Menu Menu

Cosmic signals from a black hole collision 7bn years old reach Earth

Seven billion years ago two massive black holes collided, and signs of the cataclysmic event have just reached Earth.

Astronomers claim to have detected gravitational shockwaves emanating from chaotic merger of two black holes some seven billion years ago.

The signal which provided ‘the biggest bang since the Big Bang’ rattled laser detectors in the US and Italy, telling the story of two black holes colliding and forming a previously unknown class of the stellar phenomenon.

Black holes are compact regions of space so densely packed that not even light can escape them. Until now, astronomers had only observed two forms: Stellar black holes, which occur when a star between five and 100 times the mass of our Sun collapses, and Supermassive black holes, around which entire galaxies revolve and at their smallest are millions (sometimes billions) the size of our Sun.

Until now, black holes between these two sizes weren’t known or thought to exist, as stars that grew too big before exhausting their nuclear fuel and collapsing were believed to consume themselves by default, leaving no black hole to speak of. Salvatore Vitale, of the LIGO lab at the Massachusetts Institute of Technology, revealed that he found it ‘baffling’ that we’ve stumbled across the first of its kind in 2020.

This astronomical breakthrough came through in May 2019, when two detectors picked up an audio signal of a ripple in space that lasted around one tenth of a second. Described as a brief ‘thud,’ the signal was deciphered and found to be the remnants of a violent burst of energy created by the meeting of two black holes 150 billion trillion km away, around the universe’s half birthday. In the aftermath of the event an intermediate black hole – at 142 times the mass of the Sun – was formed.

It’s worth noting that this is far from the first black hole collision we’ve observed, but the subjects involved in the previous 67 instances on record were smaller to begin with and failed to grow beyond the size of typical black holes even after merging. While it’s yet to be proven, Supermassive black holes have been thought to exist through merging with smaller black holes several times and consolidating until they become enormous. The presence of intermediary black holes has added a lot of credence to this theory.

On the other hand, scientists can’t quite explain how merged black holes would meet anywhere near frequently enough to grow so exponentially. Janna Levin, a Bernard College astronomer and author of the book Black Hole Survivor Guide claimed: ‘It’s conceivable that this pair of black holes formed entirely differently, possibly in a dense system with lots of dead stars whizzing about, which allows one black hole to capture another during a fly-by.’

Many astrophysicists find this explanation to be farfetched, instead leaning on the theory that Supermassive black holes were formed in the immediate aftermath of the Big Bang. Either way, studying the formation of intermediary black holes will go a long way to finding the truth about the formation of Supermassive black holes and therefore the universe.

Professor Alessandra Buonanno, a director at the Max Planck Institute for Gravitational Physics has stated that the sensitivity of gravitational sensors across leading observatories are currently being upgraded, meaning we will discover black holes at a more frequent rate than ever before.

Hold tight, we may just uncover the best kept secrets of the universe in our lifetime.