Scientists capture first image of two black holes circling each other

by · Mail Online

An image of two black holes circling each other has been captured for the very first time.

Astronomers spotted the celestial standoff in the heart of the galaxy OJ287, around five billion light-years from Earth.

Previously, scientists have only been able to produce images of individual supermassive black holes, such as the one at the centre of our own Galaxy.

However, scientists from the University of Turku, Finland, have now produced the first direct proof that black holes can come in pairs.

For years, scientists have suspected that OJ287 might be hiding two black holes, but there hasn't been a telescope powerful enough to tell them apart.

By combining antennas on Earth with a satellite located halfway to the moon, the astronomers created a radio telescope effectively 15 times larger than Earth.

That allowed them to take an image with a resolution 100,000 times higher than anything that had been used to observe OJ287 in the past.

Lead researcher Professor Mauri Valtonen says: 'For the first time, we managed to get an image of two black holes circling each other.'

Scientists have captured an image of two black holes circling one another for the very first time, proving that black holes come in pairs 
The pair of black holes is located at the centre of the quasar OJ287, an extremely bright galactic core around five billion light-years from Earth. Pictured: An artist's impression of OJ287

OJ287 is a type of object known as a quasar, which is an extremely bright galactic core holding a supermassive black hole.

The black hole itself doesn't give out any light, but the gas and dust falling into the singularity become so hot that they produce massive amounts of radiation.

Quasar OJ287 is actually so bright that, despite being five billion light-years away, even an amateur astronomer with a decent telescope should be able to see it.

However, in the 1980s, scientists realised that the quasar's light was fluctuating in a reliable 12-year pattern.

Professor Valtonen says: 'What is special about OJ287 is that it has been thought to harbour not one but two black holes circling each other in a twelve-year orbit, which produces an easily recognisable pattern of light variations in the same period.'

Even though scientists were pretty sure that there were two supermassive black holes hiding within the quasar, it still took decades to prove this.

Even when NASA's TESS satellite was able to detect light from both black holes in 2021, the resulting image still only showed a single object.

The problem was that normal light-based telescopes simply can't produce a high enough resolution to peel apart the signals from these extremely distant objects.

Until now, scientists have only ever been able to take images of single black holes such as the black hole at the centre of our own galaxy, Sagittarius A* (pictured)
Using a very large radio telescope, the scientists revealed that there are two black holes. A very large one at the centre, and a smaller one that orbits its neighbour once every 12 years 

What are black holes?

Black holes are areas where matter has become so dense that it forms a 'singularity'.

Their gravitational pull is so strong that not even light can escape, which is why they appear black.

Inside the singularity, the laws of physics as we understand them appear to break down and behave in unusual ways. 

Scientists think most black holes are formed when stars collapse in supernovae.

However, some supermassive black holes might have been formed right after the Big Bang, before the first stars had even formed.  

To see more, the scientists used a technique called 'Very Long Baseline Interferometry'.

This essentially involves combining radio telescopes scattered across Earth and throughout space into a single enormous 'virtual' telescope.

By adding the RadioAstron satellite, which was halfway to the moon when the images were taken, researchers were finally able to take a radio image of the quasar.

In their new paper, published in the Astrophysical Journal, Professor Valtonen compared their images to theoretical calculations and found that the black holes were exactly where they were expected to be.

Professor Valtonen says: 'In the image, the black holes are identified by the intense particle jets they emit.

'The black holes themselves are perfectly black, but they can be detected by these particle jets or by the glowing gas surrounding the hole.'

These images revealed that one of the black holes was significantly larger than the other.

The bigger has a mass about 18.35 billion times that of the sun, while the smaller is around 150 million solar masses. 

By comparing these radio images (pictured) to the theoretical models (shown as stars), the researchers showed that the jets produced by the black holes followed the exact path scientists had predicted 

That means the smaller is constantly spun around by the intense gravity, slamming through the larger black hole's accretion disk with each pass.

Every time the black hole passes through this cloud of dust and gas, the researchers estimate that it pulls away about 16 solar masses of material.

However, the larger black hole's accretion disc is so large that this barely makes a difference to the overall system.

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'Supermassive' black holes aren't as big as we thought, scientists say

In addition to proving that black hole pairs exist, the researchers also made an interesting discovery about these particle jets.

They found that the jet emanating from the smaller black hole was twisted, much like the stream of water emerging from a spinning, out-of-control firehose.

Because this smaller black hole is moving so fast around its larger neighbour, its particle jet is diverted depending on where it is currently moving.

The researchers call this a 'wagging tail' jet and predict that it should be seen twisting in different directions in the coming years when the smaller black hole changes its speed and direction.

EINSTEIN'S GENERAL THEORY OF RELATIVITY

Albert Einstein

In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers - known as the theory of special relativity.

This groundbreaking work introduced a new framework for all of physics, and proposed new concepts of space and time.

He then spent 10 years trying to include acceleration in the theory, finally publishing his theory of general relativity in 1915.

This determined that massive objects cause a distortion in space-time, which is felt as gravity.

At its simplest, it can be thought of as a giant rubber sheet with a bowling ball in the centre.

Pictured is the original historical documents related to Einstein's prediction of the existence of gravitational waves, shown at the Hebrew university in Jerusalem

As the ball warps the sheet, a planet bends the fabric of space-time, creating the force that we feel as gravity.

Any object that comes near to the body falls towards it because of the effect.

Einstein predicted that if two massive bodies came together it would create such a huge ripple in space time that it should be detectable on Earth.

It was most recently demonstrated in the hit film film Interstellar.

In a segment that saw the crew visit a planet which fell within the gravitational grasp of a huge black hole, the event caused time to slow down massively.

Crew members on the planet barely aged while those on the ship were decades older on their return.