  We examine stochastic variability in the dynamics of X-ray emission from the
black hole system GRS 1915+105, a strongly variable microquasar commonly used
for studying relativistic jets and the physics of black hole accretion. The
analysis of sample observations for 13 different states in both soft (low) and
hard (high) energy bands is performed by flicker-noise spectroscopy (FNS), a
phenomenological time series analysis method operating on structure functions
and power spectrum estimates. We find the values of FNS parameters, including
the Hurst exponent, flicker-noise parameter, and characteristic time scales,
for each observation based on multiple 2,500-second continuous data segments.
We identify four modes of stochastic variability driven by dissipative
processes that may be related to viscosity fluctuations in the accretion disk
around the black hole: random (RN), power-law (1F), one-scale (1S), and
two-scale (2S). The variability modes are generally the same in soft and hard
energy bands of the same observation. We discuss the potential for future FNS
studies of accreting black holes.
