Accretion-induced variability links young stellar objects, white dwarfs, and black holes

TL;DR

This study demonstrates that accretion physics is universal across a wide range of astrophysical objects, from young stars and white dwarfs to black holes, based on observed scaling relations and variability patterns.

Contribution

It extends the known accretion scaling relations to include young stellar objects and white dwarfs, showing a universal behavior across different accretor types.

Findings

All objects follow the same rms-flux relation.

The size of the accreting object is the key parameter in the scaling.

Accretion physics is universal from proto-stars to supermassive black holes.

Abstract

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies.