The researchers found that the size of a black hole can be determined by what it feeds on.
Supermassive black holes are millions and billions of times more massive than the Sun and are usually found at the center of massive galaxies.
They can be at rest, in which case they do not feed on gas and the surrounding stars, and also emit very little light. The only way to detect them is by gravitational effects on stars and gas, which are located near the supermassive black hole.
However, in the early universe, supermassive black holes that were still growing actively absorbed various materials and emitted huge amounts of radiation, sometimes eclipsing the entire galaxy in which they are located.
A new study by Colin Burke, a graduate student in astronomy at the University of Illinois and Professor Yue Sheng, has revealed a clear relationship between the mass of actively feeding supermassive holes and their age.
The team collected a large dataset of supermassive holes to study how their radiation changes. They determined the characteristic time scale and how the size and structure of the hole changes during this period. The researchers then compared the results with data on growing white dwarfs, the remnants of stars and found that the same ratio between their scale and mass remains.
Flicker or radiation, the authors note, is a random oscillation that occurs as a black hole feeds. Astronomers can quantify this radiation. For growing black holes, blinking starts with short bursts and ends with long bursts. The larger the black hole, the longer this transition from short bursts to long bursts.