The Lyman Alpha Forest  

Tightening Constraints from the Lyman Alpha Forest with the Flux Probability Distribution Function
A. Lidz, K. Heitmann, L. Hui, S. Habib, M. Rauch, and W.L.W. Sargent, astro-ph/0505138, ApJ 638, 27 (2006).

This web page contains electronic versions of the tables in the paper "Tightening Constraints from the Lyman Alpha Forest with the Flux Probability Distribution Function". Below is a brief decsription of the tables and some instructions for use.

  • There are tables with names like "q0000.use.dat". These tables indicate the wavelength ranges used in our analysis for each quasar spectrum. Other data are excluded due to the possible presence of metal lines, damped lyman-alpha systems, or spurious pixels. See also Rauch et al. (1997), McDonald et al. (2000).

  • Tables with names like "z2.26_var.dat". These tables give an estimate of the flux pdf and its variance in a given redshift bin. The tables have columns with the delta-bin number, the average pdf in the bin, the average delta_f in the bin, and an estimate of the variance in the bin.

  • Tables with names like "z2.26_cov.dat". These tables give an estimate of the correlation coefficient of the flux pdf estimates between different bins. The first two columns give the bin numbers of the ith, and jth bin. The next two columns give the average delta_f in the ith and the jth bin respectively. Finally, the last column is the correlation coefficient between the ith and jth bin: r(i,j)=cov(i,j)/sqrt(var(i)*var(j)).

Baryonic Density
  • One can use the symmetry of the correlation matrix (r(i,j)=r(j,i)) to build-up the entire correlation matrix from the table. The covariance matrix can then be inferred using this table, and the relevant variance table.

  • Finally, to compute chi^2 between the data and a model, one should 'regularize' the covariance matrix, as described in the paper.

    Please direct any questions to alidz@cfa0.cfa.harvard.edu

    The Tables

    The tables which we used in our paper are given below, or you can download them here. We don't show the tables for the estimates of the correlation coefficient of the flux pdf since they are rather long, but they are included in the downloadable file. The tar-file contains all the tables and an additional README file with the same information as given above.