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Professor Simone Scaringi, from our Department of Physics, has been part of an international study calculating the size of Supermassive black holes (SMBHs) by looking at their feeding patterns.

What is a SMBH? 

A SMBHs is a colossal black hole which weighs millions to billions of times more than the mass of the sun, and will usually be found at the centre of massive galaxies.

They are surrounded by an accretion disk, which is a disk-like flow of gas, particles and stars that spirals inwards towards the SMBHs.

Normally astronomers can detect SMBHs by the light or flickering the accretion disk emit. But when dormant and not feeding on the gas and stars surrounding them, the accretion disk releases very little light, making it difficult for astronomers to detect the whereabouts of an SMBH. 

Watching their feeding patterns

Until now, the pattern or reason why SMBHs emit light or flicker has been relatively unknown.

In this latest study, the team compiled a large quantity of data for actively feeding SMBHs and analysed the light pattern alongside it. The team believes that the light being emitted from SMBHs comes at the end of the feeding process, a bit like a astronomical burp, with smaller SMBHs going through the process quicker than larger ones.

The researchers compared black hole feeding to our very own eating habits whereby babies will frequently need to be burped but adults can hold it for longer. For SMBHs this same is true; smaller SMBHs, like babies, go through the feeding process quicker and therefore flicker, or ‘burp’ more regularly.

What does this mean?

The connection between the light emissions and feeding of SMBHs will allow researchers to understand their feeding process and changes in mass.

The findings will also help astronomers analyse white dwarfs, which are remnants of stars but are millions to billions of times smaller than SMBHs.

When the data retrieved for the SMBHs was compared to white dwarfs, the researchers remarkably found that the light variation timescales of days-to-weeks for SMBHs were closely resembled by the much smaller white dwarfs but in the space of minutes.

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