What is the universal cosmic law

Universal law for cosmic matter influx

Many cosmic objects grow through the influx of matter - whether they are emerging stars, white dwarfs or black holes of all sizes. Apparently, completely independent of the type and size of the central object, completely identical processes take place, which can be described with a uniform law. This is shown by the evaluation of fluctuations in the brightness of such objects by an international team of researchers. The decisive parameter for the process is not, as previously assumed, the mass of the central object, but the size of the inner disk in which the incoming matter collects, according to the scientists in the journal "Science Advances".

Accretion disk around the emerging star

"Since the matter flowing towards an object from the outside almost always has a torque, a rotating disk forms in which the matter is slowly transported inwards," say Simone Scaringi from the Max Planck Institute for Extraterrestrial Physics and his colleagues. The researchers speak of an “accretion disk”, whereby accretion is the technical term for the collection of matter. "Since we do not yet fully understand the physical processes that take place, it was not yet clear whether these processes proceed in the same way for the very different objects."

During accretion, the matter heats up and emits radiation. The astrophysicists receive important information about the processes taking place from variations in the brightness of the accretion disk. Observations of these brightness fluctuations have already shown in the past that the accretion processes in stellar black holes - i.e. the remains of massive stars - are scaled-down versions of the processes in supermassive black holes in the centers of galaxies. "If the physics of accretion is so universal, then it should also apply to other objects that collect matter," said Scaringi and his colleagues.

The team therefore searched the data from the Kepler Space Observatory for young stars in their formation phase, as well as matter-collecting white dwarfs, analyzed their variability and compared them with the variability of black holes. It was found that there is a uniform relationship between the luminosity of the disk and the mean amplitude of its variability for all objects. What surprised the researchers was that the decisive parameter for the process is not - as previously assumed - the mass of the celestial body, but the size of the inner accretion disk. What this means in concrete terms for the physical models of accretion is not yet clear. Scaringi and his colleagues are certain, however, that the new analysis provides a solid basis for the development of a universal physical model for astrophysical accretion processes.