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Supercomputer provides black hole breakthrough

January 10, 2018

Black holes are regions of space-time whose gravitational effects are so strong that even electromagnetic radiation such as light cannot escape from inside of them.

As such they are incredibly difficult to study, although a collaboration between researchers from Northwestern University and the University of Amsterdam in the Netherlands has managed just that.

They were examining the “relativistic jets” from black holes, the material that actually does manage to escape from them – one of the most mysterious phenomena in modern astronomy.

As explained by Northwestern University: “Similar to how water in a bathtub forms a whirlpool as it goes down a drain, the gas and magnetic fields that feed a supermassive black hole swirl to form a rotating disk – a tangled spaghetti of magnetic field lines mixed into a broth of hot gas.

“As the black hole consumes this astrophysical soup, it gobbles up the broth but leaves the magnetic spaghetti dangling out of its mouth. This makes the black hole into a kind of launching pad from which energy, in the form of relativistic jets, shoots from the web of twisted magnetic spaghetti.”

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In a black hole gravity is so powerful it traps light and distorts time and space
Image:An artist’s impression of a black hole

The scientists ran complicated simulations on one of the world’s most powerful supercomputers and discovered that these relativistic jets actually changed direction as a result of space-time itself being dragged into the rotation of the black hole.

“Understanding how rotating black holes drag the space-time around them and how this process affects what we see through the telescopes remains a crucial, difficult-to-crack puzzle,” according to one of the researchers.

Alexander Tchekhovskoy, assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences, said: “Fortunately, the breakthroughs in code development and leaps in supercomputer architecture are bringing us ever closer to finding the answers.”

The researchers discovered that where previously simulations considered the disks and the axis of the black hole’s rotation were aligned, in reality they are unlikely to be parallel.

The study confirmed that these tilted disks, which are likely to include the disk of the black hole at the centre of our own galaxy the Milky Way, change direction, much like a spinning top, causing the direction of the relativistic jets to change too.

“The high resolution allowed us, for the first time, to ensure that small-scale turbulent disk motions are accurately captured in our models,” Mr Tchekhovskoy said.

To the researcher’s surprise the motions turned out to be so strong that they caused the disk to fatten up and the direction changing to stop.

The results of their research are now being applied to interpreting the observations of the Event Horizon Telescope examining the black hole at the centre of the Milky Way.