Temporal 1/f(alpha) fluctuations from fractal magnetic fields in black-hole accretion flow

Rapid fluctuation with a frequency dependence of 1/f(alpha) (with alpha sim ilar or equal to 1-2) is characteristic of radiation from black-hole object s. Its origin remains poorly understood. We examined three-dimensional magn etohydrodynamical simulation data, finding that a magnetized accretion disk exhibits both 1/f(alpha) fluctuation (with alpha similar or equal to 2) an d a fractal magnetic structure (with the fractal dimension of D similar to 1.9). The fractal field configuration leads to reconnection events with a v ariety of released energy and duration, thereby producing 1/f(alpha) fluctu ations.