CLUSTERING PROPERTIES OF THE LY$\alpha$ CLOUDS

Abstract

The spectra of the QSOs PKS2126-158 ($z_{em}=3.27$) and Q0055-269 ($z_{em}=3.66$) have been observed at high resolution ($2.2-2.7\times 10^4$). Significant clustering, with $\xi \simeq 1$ at $\Delta v=100$ km s${}^{-1}$, is detected in both cases for lines with $\log N_{HI}\ge 13.8$. A similar result is obtained analysing the data available in the literature for Q0014+81. An anticlustering signal is also detected on scales $\Delta v\sim 600$ km s${}^{-1}$. Two voids of size $\sim 2000$ km s${}^{-1}$ are found in the spectrum of Q0055-269 with a probability of $2\times 10^{-4}$.

4 pages uuencoded compressed postscript, to appear in the proceedings of the XXXth MORIOND meeting: "Clustering in the Universe"