Researchers at the University of Illinois Urbana-Champaign have discovered that black holes emit flickers of light – akin to a ‘burp’- when they’re consuming gas and stars around them and this change in brightness is directly correlated to their size.

Supermassive black hole (SMBHs) are billions to billions of times larger than the sun and usually reside in the center galaxies. This includes the one known as SagittariusA*, which is the center of the Milky Way.

SMBHs don’t often emit much light when they are dormant. The radiation they emit when they are active, which is usually at the dawning of the universe, sometimes outshines galaxies. Their flickering light can range from hours to decades and provide a wealth of information.


These black holes can be found in the center of most galaxies.

They are millions to billions of times more massive than the Sun’s and they allow no escape, not light.

Sagittarius A* is the name of the supermassive blackhole in the Milky Way.

A class of ultramassive dark holes is also available, which have a mass at least 10 times that of the son.

These black holes, which are 100 billion times larger than the sun’s mass, have been called stupendously large.

‘There have been many studies that explored possible relations of the observed flickering and the mass of the SMBHs, but the results have been inconclusive and sometimes controversial,’ said the study’s lead author, Colin Burke, in a statement.

A large amount of matter is swallowed by a supermassive blackhole. The black hole’s gravity causes the matter to accelerate at great speed. This energy can cause the matter surrounding it to push outwards. This is how the galactic winds are created.

However, it is still not clear why flickering occurs due to “physical processes that aren’t yet understood”.

Researchers looked at a variety of characteristics, including the timescale to determine if the pattern changes over time and if it correlates to the SMBH’s weight.

They also examined the results of accreting White dwarfs, which are remnants of stars like the sun, and discovered that there was a timescale mass correlation, despite white dwarfs being significantly smaller than black hole.

Smaller SMBHs are more likely to be operational in a short time span, while larger SMBHs can last for a longer period of time.

“These results suggest that flickering during acceleration is universal, regardless of whether the central object of the study is a supermassive dark hole or a lighter white dwarf,” Yue Shen, University of Illinois Urbana-Champaign, said.

Yan-Fei Jiang, co-author of the study, said that establishing a link between the observed light flicker (and fundamental properties of an accretor) will help us better understand accretion process.

These flickers of light could help to determine the sizes of SMBHs or white dwarfs. They may also be used by researchers to uncover intermediate-mass Black holes (IMBHs), which have a mass between 100 and 100,000 times that of the sun. Only one of these IMBHs has been discovered.

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Burke said, “Now that we have a correlation between flickering patterns and the mass central accreting object (CACC), we can use it for prediction of what flickering signal from IMBH might look,’ Burke further.

The study was published Thursday in the journal Science.

Researchers have been fascinated by black holes and their existence for a long time.

The first image of a black hole’s event horizon – the ring of light around the perimeter- was unveiled in April 2019, after scientists spent years probing Sagittarius A*.