Routing protocol

Combinatorics

Physics

Corona (planetary geology)

Computer network

Mathematics

Black hole (networking)

Link-state routing protocol

Galaxy

Aperiodic graph

Optics

Statistics

Astronomy

Amplitude

Accretion (finance)

Thin disk

Metallurgy

Materials science

Accretion disc

Venus

Computer science

Astrophysics

Spectral line

Routing (electronic design automation)

Power law

Flux (metallurgy)

Astrobiology

Monthly Notices of the Royal Astronomical Society

Two-component X-ray spectra (soft multicolour black-body and harder power law) are frequently observed from accreting black holes. These components are presumably associated with the different parts of the accretion flow (optically thick and optically thin respectively) in the vicinity of the compact source. Most of the aperiodic variability of the X-ray flux on the short time-scales is associated with the harder component. We suggest that drastically different amplitudes of variability of these two components are simply related to the very different viscous time-scales in the geometrically thin and geometrically thick parts of the accretion flow.

Soft state of Cygnus X-1: stable disc and unstable corona