The astronomers detected a gravitational wave from a black hole so massive that, according to what we know, it should not exist.
The black hole formed by the collision that sent the gravitational wave into space is 142 times the mass of the Sun, making it the most massive ever observed from gravitational waves, while the energy released through the universe is equivalent to about eight solar masses.
Scientists are still unsure of how it could have been created and how it could have caused such a powerful explosion , despite years of work spent hunting for black holes.
"The system we discovered is so strange that it overturns a number of previous hypotheses about how black holes form," said Karan Jani, a researcher at Vanderbilt University who participated in the study. "It took us over a year to confirm that this alien black hole exists, and we are excited to share this discovery with the world."
One scenario is that it formed when two smaller black holes collided to create a larger one, which then found a third black hole, resulting in an even larger collision. The probability of this happening is less than throwing a golf ball from China and another from Argentina and seeing them collide in mid-air.
"This discovery raises more questions than it answers," said Alan Weinstein, a LIGO member and Caltech. "From a discovery and physics perspective, it's very exciting."
Since 2015, scientists have observed a black hole that forms in the collision of two others using gravitational waves, as the powerful energy from their merger propagates through the universe, oscillates in space, and can be collected on Earth.
But the newly discovered signal is particularly special. It was called GW190521 and was detected in May last year by LIGO and VIRGO, gravitational wave detectors in the US and Italy. The signal consisted of four small oscillations that lasted less than a tenth of a second.
Whatever the conditions that created the black hole, it has already broken many records. It is the most distant and the oldest ever detected, with gravity waves that take seven billion years to reach Earth, and it is also the most massive black hole ever observed via gravitational waves.
The medium-mass black holes – which have been observed only indirectly – could provide some clue to one of the biggest issues in astrophysics and cosmology, allowing scientists to understand where these supermassive black holes come from. Researchers have reported that they could continue merging until they evolve into a kind of «cosmic monster», in the middle of galaxies, including our own.
It is not only that black hole which was extremely large. The two that collided to form it had masses about 65 and 85 times larger than that of the Sun.
Theories also want it to be the so‑called «primordial» black hole, which formed during the Big Bang.
The discovery is reported in two publications today, in Physical Review Letters, which details the discovery of the gravitational wave signal itself, and in Astrophysical Journal Letters, which explores the physical properties and implications of that signal.
