Monumental Collision of “Impossible” Black Holes Detected for the First Time

Artist’s impression of binary black holes about to collide. Photo credit: Mark Myers, ARC Center of Excellence for Gravitational Wave Discovery (OzGrav)

The most massive black hole The collision ever detected was directly from the LIGO and VIRGO Scientific Collaboration, to which scientists from The Australian National University (ANU).

The short gravitational wave signal GW190521, recorded by the LIGO and Virgo gravitational wave observatories in the US and Europe on May 21 last year, came from two spinning black mammoth holes weighing 85 times and 66 times the mass of the sun.

However, this is not the only reason this system is very special. The larger of the two black holes is considered “impossible”. Astronomers predict that between 65 and 130 times the mass of the Sun, stars go through a process known as pair instability. This causes the star to blow apart and nothing is left behind.

With a mass of 85 solar masses, the larger black hole falls exactly in the forbidden area called the black hole’s upper mass gap and should be “impossible”. So if it wasn’t created by the collapse of a star, how was it formed?

“We see black holes as vacuum cleaners of the universe. They suck in everything in their path, including gas clouds and stars, ”said Professor Susan Scott of the ANU Research School of Physics, co-author of the paper.

“They also suck in other black holes, and it is possible to create ever larger black holes through the ongoing collisions of previous generations of black holes. The heavier “impossible” black hole in our detected collision could have been created this way. ”

The two black holes merged when the universe was only about seven billion years old, which is roughly half its age today. They formed an even larger black hole that weighed a whopping 142 times the mass of the Sun, by far the largest black hole ever observed through gravitational wave observations.

Black holes with a mass of 100 to 100,000 solar masses are known as intermediate mass black holes (IMBHs). They are heavier than star-mass black holes, but lighter than supermassive black holes, which are often located in the centers of galaxies. There were no conclusive electromagnetic observations for IMBHs in the mass range of 100 to 1000 solar masses.

“The ‘impossible’ black hole created by the collision is located in the desert of the black hole between 100 and 1000 times the mass of the sun,” said Professor Scott, who is also the chief investigator at the ARC Center of Excellence for Gravitational Wave Detection (OzGrav) ) said.

“We are very pleased to have achieved the first direct observation of an IMBH in this mass range. We also saw how it was created, which confirms that IMBHs can be made by the fusion of two smaller black holes. ”

Another recent study suggests that scientists using Caltech’s Zwicky Transient Facility may have detected a slight flare-up from the collision. This is surprising since black holes and their fusions are usually dark to telescopes. One theory is that the system may orbit a supermassive black hole. The newly formed black hole may have been kicked by the collision, shoot in a new direction, and flow through the disk of gas surrounding the supermassive black hole, causing it to light up. While the GW190521 detection is unlikely to have come from the same event as the torch, researchers say the possibility that it did is intriguing.

“There are a number of different environments in which this system of two black holes could have formed, and the gas disk surrounding a supermassive black hole is certainly one of them,” said OzGrav postdoctoral researcher Dr. Vaishali Adya from the ANU.

“But it is also possible that this system consisted of two original black holes that formed in the early universe.

“Every observation we make of two colliding black holes gives us new and surprising information about the life of black holes throughout the universe. We are beginning to fill the previously assumed mass gaps of the black hole with “impossible” black holes that have been revealed by our discoveries. ”