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Session 23 - High Luminosity AGN and QSOs.
Oral session, Monday, June 10
Union Theater,

[23.08] Comparing Simulations and Observations of the Ly\alpha Forest

R. Daveé, L. Hernquist (UCSC/Lick), N. Katz (U.Washington), D. Weinberg (Ohio St.), C. Churchill (UCSC/Lick)

We reanalyze the artificial spectra generated in the Hernquist, et al (1996) CDM hydro simulations of the Lyman alpha forest using Voigt profiles fitting, and find substantial differences in the resulting statistical properties of Ly\alpha forest absorbers. The semi-automated analysis algorithm adds noise to artificial spectra to emulate HIRES data, fits a continuum in IRAF, identifies lines as > 5\sigma fluctuations, deconvolves blended lines into individual Voigt profiles, and uses a \chi^2-minimization routine to find the best-fit values for N_HI and b. This algorithm is intended to be applicable to both real and artifical data, and is intended to emulate the manner in which QSO spectra are generally analyzed. In contrast, the algorithm in Hernquist, et al (1996) used a flux threshold algorithm to identify lines, and performed no deblending. The resulting distributions of N_HI and b-parameters are in significantly better agreement with Keck HIRES results. The sensitivity of the results to the analysis method indicates that artificial spectra must be analyzed in a very similar manner to real spectra when comparing model predictions to data.

Program listing for Monday