Geometrical Properties of Avalanches in a Pseudo-3D Coronal Loop

MORALES, L.F. ; CHARBONNEAU, P.

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2009 vol. 698 p. 1893 - 1902

0004-637X

We investigate the geometrical properties of energy release of synthetic coronal loops constructed using a recently published self-organized critical avalanche model of solar flares. The model is based on an idealized representation of a coronal loop as a bundle of closely packed magnetic flux strands wrapping around one another in response to photospheric fluid motions, much as in Parker's nanoflare model. Simulations are performed with a two-dimensional cellular automaton that satisfies the constraint ∇ B = 0 by design. We transform the avalanching nodes produced by simulations into synthetic flare images by converting the two-dimensional lattice into a bent cylindrical loop that is projected onto the plane of the sky. We study the statistical properties of avalanches peak snapshots and time-integrated avalanches occurring in these synthetic coronal loops. We find that the frequency distribution of avalanche peak areas A assumes a power-law form with an index α A 2.37, in excellent agreement with observationally inferred values and reducing error bars from previous works. We also measure the area fractal dimension D of avalanches produced by our simulations using the box counting method, which yields 1.17 ≤ D ≤ 1.24, a result falling nicely within the range of observational determinations.