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Q 0454+039
V = 16.5; z = 1.343; exp = 4500 s; coverage = 3765.8-6198.9 A
Spectra of this QSO were previously studied by Burbidge et al. (1977), Caulet (1989), SS92, and Steidel et al. (1995). Two systems have been studied in this work. The damped systems has been presented in detail by Lu et al. (1996b) for a study of damped Ly-alpha "galaxies".
z=0.859565 |DATA & VOIGT PROFILES| |EWs & AOD COLUMNS| |VP PARAMETERS|
This damped Ly-alpha system was studied by Steidel et al. (1995) and by Lu et al. (1996b). The Mg II 2796 transition and the Ca II 3934, 3969 doublet were not observed because they were not covered by the HIRES format. The overall Mg II 2803 profile was found to be a single fully saturated feature with a ~200 km/s spread. Beyond the red wing, there is a small absorption profile, which typically accompany profiles with this type of overall shape morphology. The system was fit with a total of 12 VP components. However, the column densities and Doppler b values for components three through nine are not well constrained, and any inferences regarding this system based upon the VP decomposition should be viewed with caution. Based upon the profile fit to the Fe II 2344 transition, there may be an offset in the continuum placement across that profile.
z=1.153248 |DATA & VOIGT PROFILES| |EWs & AOD COLUMNS| |VP PARAMETERS|This system exhibits a very interesting, and somewhat unique profile. It is the only profile in the sample that has weak high velocity absorption distributed symmetrically about the central main absorption region. However, there is confusion near both the Mg II doublet transitions, in that small unidentified absorption features are seen. Though these features do not fit any obvious pattern expected of low ionization transitions, it is possible they arise from an unidentified redshift system. Additionally, the Fe II 2374 transition is blended with an unidentified absorption line. This is apparent because of the unphysical strength ratios with respect to the other Fe II transitions and is further suggested by another possible nearby unidentified feature. For the overall system, three kinematic subfeatures were found and seven VP components were fit. The Ca II 3934, 3969 doublet and the Mn II 2606 transition were not covered by the HIRES format.
Note on Comparison with Lu et al. (1996)It should be noted that the accepted apparent column densities for the z = 0.8596 system, quoted in Table 3.18, are systematically smaller than those quoted by Lu et al. (1996). This is due to the definition of the optical depth applied in this work. In the case when the flux value in a given pixel is less than the uncertainty in that pixel, the flux value is replaced by the uncertainty. This gives a lower limit on the optical depth, and results in systematically smaller apparent column density values.
Post Thesis WorkFOS/HST data have been investigated.
See Churchill et al. (2000a)
See Churchill et al. (2000b)
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