Power law distributions of burst duration and interburst interval in the solar wind: Turbulence or dissipative self-organized criticality?

Abstract

We calculate the probability density functions P of burst energy e, duration T, and interburst interval $\tau$ for a known turbulent system in nature. Bursts in the Earth-Sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find $P\left(e\right)\mathrm{}$ and $P\left(T\right)\mathrm{}$ to be power laws, consistent with self-organized criticality (SOC). We find also a power-law form for $P\left(\tau \right)$ that distinguishes this turbulent cascade from the exponential $P\left(\tau \right)$ of ideal SOC, but not from some other SOC-like sandpile models. We discuss the implications for the relation between SOC and turbulence.