AAS 199th meeting, Washington, DC, January 2002
Session 131. QSO Absorption Lines
Display, Thursday, January 10, 2002, 9:20am-4:00pm, Exhibit Hall

## [131.04] Comparing Simulations and Observations of the Lyman-Alpha Forest II. The Coherence Length at z ~2

C.E. Petry, C.D. Impey (Steward Obs.), N.S. Katz (U. Massachusetts), D.H. Weinberg (Ohio State U.), L.E. Hernquist (Harvard U.)

We directly compare observations of two quasar pairs and one quasar triplet to hydrodynamic simulations at z ~2. In Paper I of this series, we described an automated process for selecting absorption lines in spectra which were extracted from the simulations to mimick quasar pairs with proper separations of up to 1 h-150 Mpc at z=2. Line coincidences and anti-coincidences were tracked without prior definition of a velocity match window, unlike most previous studies. A direct comparison was made between correlation measured by the statistics of coincident lines and correlation measured by a continuous statistic. In this work, we apply these techniques to both observed quasar spectra and spectra extracted from the simulations. We present the coincident absorber statistics, and we examine the strengths and limitations of the line-fitting methodology as a tool to measure coherence. We also present a measure of the Lyman-Alpha coherence for both the data and simulations based on continuous flux statistics. Ultimately, these techniques will be applied to data and simulation spectra over a range in redshift to probe cosmological parameters.