Finite-size scaling of critical avalanches

TL;DR

This paper investigates the finite-size effects on avalanche size distributions in self-organized critical systems, revealing scaling behaviors, critical exponents, and implications for different sandpile models.

Contribution

It introduces a systematic scaling analysis to accurately estimate critical exponents and clarifies the avalanche size exponent for various sandpile models.

Findings

Avalanche size distribution shows a logarithmic dependence on system size.

The avalanche size exponent is suggested to be 1 for the prototype sandpile.

In bulk-driven sandpile models, the exponent is slightly less than 1.

Abstract

We examine probability distribution for avalanche sizes observed in self-organized critical systems. While a power-law distribution with a cutoff because of finite system size is typical behavior, a systematic investigation reveals that it may decrease on increasing the system size at a fixed avalanche size. We implement the scaling method and identify scaling functions. The data collapse ensures a correct estimation of the critical exponents and distinguishes two exponents related to avalanche size and system size. Our simple analysis provides striking implications. While the exact value for avalanches size exponent remains elusive for the prototype sandpile on a square lattice, we suggest the exponent should be 1. The simulation results represent that the distribution shows a logarithmic system size dependence, consistent with the normalization condition. We also argue that for train or Oslo sandpile model with bulk drive, the avalanche size exponent is slightly less than 1 which is significantly different from the previous estimate 1.11.