A study of natural frequencies in a dynamic corona - disk system

Vol. 657
2. Astrophysical processes

A study of natural frequencies in a dynamic corona - disk system

by A. Mastichiadis, M. Petropoulou, and N. Kylafis 2022, A&A, 662, A118 alt

Quasi-periodic oscillations (QPOs) in X-ray binaries were discovered long ago, with the EXOSAT satellite back in 1985. As the name states, they are not coherent periodicities, but flux oscillations at a characteristic frequency. Quasi-periodic oscillations in X-ray binaries have been classified into three types (A, B, and C). Type-C QPOs occur in the range of a few tens of millihertz to a few tens of hertz, and their frequency increases with the source luminosity. Several mechanisms have been put forward to explain type-C QPOs. In this paper, Mastichiadis and collaborators show that these QPOs can arise naturally from the interaction of a hot corona with the accretion disk. The hot electrons of the corona can be viewed as the prey of the soft disk photons, which act as predators. This behavior establishes a typical pray-predator pattern, generating the QPO.