Lyman Alpha Forest Clustering Using Cell Counts Statistics

Abstract

We present a novel technique for calculating \Lya forest correlations based on cell counts. It is applied to the line lists from 7 QSOs observed at high resolution ($\Delta v<25\kms$). Two spectra (Q0055$-$259 and Q0014$+$813) appear to be sufficiently free of biases to obtain meaningful estimates. We find for both positive correlations, with a maximum of $0.5-1$, on the scale of $0.5-3 h^{-1}$ Mpc (comoving), or $100-600\kms$, which is consistent with the primordial power spectrum inferred from optically-selected galaxy surveys. Strong evidence for anti-correlation on the scale of $3-6 h^{-1}$ Mpc is also found. If this first detection of anti-correlations is physical, additional factors to gravity may play a role in determining the clustering of the \Lya forest on comoving scales $> 3h^{-1}\Mpc$.}