1997/09/09 by Uffe Hellsten, Lars Hernquist, Hellsten, Uffe +5
Biochemistry, Genetics and Molecular Biology · Engineering · Mathematics · #Geomagnetism and Paleomagnetism Studies #Calibration and Measurement Techniques #Advanced Research in Science and Engineering
paper · doi:10.48550/arxiv.astro-ph/9709075
The metal absorption lines found in association with \lya absorbers of moderate to high HI column density contain valuable information about the metallicity and ionization conditions within the absorbers and offer a stronger test of models of the intergalactic medium at ∼ 3 than HI absorption lines alone. We have developed a method to predict the strengths of metal absorption lines within the framework of cosmological models for the \lya forest. The method consists of evaluating a quantity, the Line Observability Index, for a database of hundreds of candidate metal lines, allowing a comprehensive identification of the lines the model predicts to be detectable associated with a \lya absorber of a given HI column density and metallicity. Applying this technique to a particular class of models at ∼ 2-4, we predict that the OVI(1032 Å, 1038 Å) doublet is the only practical probe of the metallicity of low column density absorbers (HI \simlt 1014.5 cm-2), that CIV (1548 Å) is the strongest line with rest wavelength λr > 1216 Å regardless of HI, and that the strongest metal lines should be CIII(977 Å) and SiIII(1206.5 Å), which peak at HI ∼ 1017 cm-2.