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

Abstract

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) Lyα transmission spectra. Using a space‐scale decomposition, the Discrete Wavelet Transform (DWT), we show that the field traced by Lyα 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.