Intermittency and Large-Scale Structure in the Universe: A New Window for the Study of the Nonlinear Regime of Structure Formation

摘要

We study the weak nonlinear regime of structure formation using high resolution and high signal-to-noise ratio (S/N) samples of Quasi Stellar Objects' (QSOs) Lya transmission spectra. Using a space-scale decomposition, the Discrete Wavelet Transform (DWT), we show that the field traced by Lya transmission flux is intermittent on scales less than 2000 km/s. The distribution of the local power of fluctuations is spiky with almost no power between the spikes. This spike-gap-spike feature gets more pronounced on smaller scales (128 - 16 km/s). We show that the structure functions and the intermittent exponent are not only able to quantitatively differentiate between different dark matter models but also qualitatively describe the nature of non-Gaussianity. Structure functions and the intermittent exponent are powerful tools for describing an intermittent field.