Published online by Cambridge University Press: 12 April 2016
Flickering is a poorly understood phenomenon associated with accretion processes, but this does not suffice to make it interesting. Why then should we bother studying this ‘noise’? Three reasons come to mind: (i) flickering is a fundamental signature of accretion, to the point of being a necessary characteristic (if it doesn’t flicker, it’s not a CV); (ii) energetically, flickering is not a small effect and can contribute up to a few tens of percent of the total luminosity of the system (hence it is often more luminous than the entire secondary star); (iii) flickering is inherently a time-dependent phenomenon and it is hoped that it can provide clues to the nature of the disc viscosity, something that time-independent theory cannot provide.