Repetitive Patterns in Rapid Optical Variations in the Nearby Black-hole Binary V404 Cygni

Understand

How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics.

• It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate.
• When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disc, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours.
• In fact, such oscillations have been observed only in sources with a high mass accretion rate, such as GRS 1915+105.