Scientists create film of black hole feeding off companion star

Saturday, 12 October 2019

Energetic flaring revealed around a black hole

PUNE: An international team of astronomers, including those from University of Southampton, UK and the Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune have used state-of-the-art cameras to create a high frame-rate movie of a growing black hole system at a level of detail never seen before. 

In the process, they have uncovered new clues to understanding the immediate surroundings of the illustration impression of the black hole system MAXI J1820+070, based on its observed characteristics. The black hole is seen to feed off the companion star, drawing the material out into a vast disc. As it falls closer to the black hole itself, some of that material is shot out into energetic pencil-beam above and below the disc. The light here is intense enough to outshine the Sun a thousand times over.
John Paice, a joint PhD student at the University of Southampton and the IUCAA was the lead author of the study presenting these results and also the artist who created the movie. He is part of an Indo-UK programme led by Prof Poshak Gandhi of University of Southampton and Prof Ranjeev Misra of IUCAA. 

The black hole system studied is ‘MAXI J1820+070’ and was first discovered in early 2018. It is only about 10,000 light years away, in our own Milky Way Galaxy. 

It weighs the equivalent of about seven Suns, with this mass collapsed down to a region of space smaller than the city of London.

Black holes can feed off a nearby star and create vast accretion discs of material. Here, the effect of the black hole’s strong gravity and the material’s own magnetic field can cause rapidly changing levels of radiation to be emitted from the system. This radiation was detected in visible light by the HiPERCAM instrument on the Gran Telescopio Canarias (La Palma, Canary Islands, Spain) and in X-rays by NASA’s NICER observatory aboard the International Space Station (ISS).  

Investigating these systems is difficult, as their distances make them too faint and small to see. Such observations are not possible even by the Event Horizon Telescope (EHT), which recently took a picture of the black hole at the centre of the galaxy. 

However, the HiPERCAM and NICER instruments allowed researchers to record ‘movies’ of the changing light from the system at over three hundred frames per second, capturing violent ‘crackling’ and ‘flaring’ of visible and X-ray light. A split-second time difference between X-ray and visible light (as illustrated in this movie), has been seen in two other systems hosting black holes but it has never been observed at this level of detail.

“The fact that we now see this in three systems strengthens the idea that it is a unifying characteristic of such growing black holes. This tells us something fundamental about how plasma flows around black holes operate. Our best ideas invoke a deep connection between inspiralling and outflowing bits of plasma. But these are extreme physical conditions that we cannot replicate in Earth laboratories, and we don’t understand how nature manages this. Such data will be crucial for moving forward on the correct theory.”
—Prof Poshak Gandhi, University of Southampton

“Path-breaking discoveries like this often need collaborators and facilities from across the world bringing together a whole range of skills and instruments. I am so glad that IUCAA has been able to play a leading role in this discovery and I hope this collaboration will continue to produce more stunning results.”
—Prof Somak Raychaudhury, Director, IUCAA

“The movie was made using real data but slowed down to 1/10th of the actual speed to allow the most rapid flares to be discerned by the human eye. Here we see how the material around the black hole is so bright, it’s outshining the star and consuming it. The fastest flickers last only a few milliseconds – that’s the power of a hundred Suns and more being emanated at the blink of an eye!”
—John Paice, Lead author of the study

“This difficult work using the most advanced observatories required a large international collaboration involving several countries. However, the driving force was the unique Indo-UK programme between IUCAA and University of Southampton led by Prof Poshak Gandhi and myself. Our joint PhD student John Paice was the main conduit through which two-way knowledge transfer was made possible between the UK and India.”
—Prof Ranjeev Misra, IUCAA


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