The intermittent behavior of the cosmic mass field revealed by a QSO's Ly alpha forest

The intermittent behavior of the space-scale distribution of the Ly alpha - transmitted flux of QSO HS 1700+64 has been analyzed via a discrete wavelet transform. We found that there are two strong indications of intermittency on scales down to about 10 h(-1) kpc: (1) the probability distribution fun ction of the local fluctuations of the flux has a significantly long tail o n small scales, and (2) the local power spectrum of the flux shows prominen t spiky structures on small scales. Moreover, the local power spectrum, ave raged on regions with different sizes, shows similar spiky structures. Ther efore, the random mass density field traced by the Ly alpha forest is rough er on smaller scales, consistent with singular clustering.