Large-scale structure in the Lyman-alpha forest -- A new technique

Abstract

We present a new technique for detecting structure on Mpc scales in the Lyman-alpha forest. The technique is easy to apply in practice since it does not involve absorption line fitting but is rather based on the statistics of the transmitted flux. It identifies and assesses the statistical significance of regions of over- or underdense Lyman-alpha absorption and is fairly insensitive to the quality of the data. Using extensive simulations we demonstrate that the new method is significantly more sensitive to the detection of large-scale structure in the Lyman-alpha forest than a traditional two-point correlation function analysis of fitted absorption lines.