| |< | | < | | ^ | | > | | >| |
Q 1225+317
V = 15.9; z = 2.219; exp = 2400 s; coverage = 5737.5-8194.7 A
Spectra of this QSO were previously studied by SYBT, YSB, Pettini, Sargent, & Boksenberg (1981, unpublished), York et al. (1984), Bechtold, Green, & York (1987), Caulet (1989), and SS92. The last authors provide a nice description of the history of study of this QSO spectrum. A single system is studied for this work. As with the Q 1213-003 systems, this system was selected for its large equivalent width, reported multiple Fe II transitions, and high redshift. As such it is not an unbiased member of the sample.
z=1.794833 |DATA & VOIGT PROFILES| |EWs & AOD COLUMNS| |VP PARAMETERS|
This system is very similar to the z = 1.3201 absorber in the Q 1213-003 spectrum. It also exhibits a large double saturated trough like that seen along the line of sight to SN 1993J (Bowen, Blades, & Pettini 1995). However, based upon the a study of the relative profile shapes of both high and low ionization species, Bechtold, Green, & York conclude that the data "favor the interpretation that the system is a single large galaxy halo, rather than the superposition of absorption arising in overlapping halos of galaxies in a cluster". A total of 18 VP components were fit to the system. Even though this is a large number of components, it should be noted that the number is probably an underestimate because strong blending is occuring (see Chapter 4). This is also illustrated in Figure 3.6 - provided the linear relation between the system EW(rest) and N_cl holds for all systems. The Fe II 2587 and the Mn II 2594 transitions, and the Ca II 3934, 3969 doublet were not covered by the HIRES format. The two other Mn II transitions showed no absorption to the EW(rest) limits given in Table 3.33.
Special Note on Reduction and AnalysisThe Mg II 2803 transition was cut off by the CCD edge at v = 300 km/s. Because the signal to noise in this region is somewhat reduced and because of the large spread in the absorption system, accurate continuum normalization for v > +100 km/s was difficult. As can be seen by the VP model spectra, the continuum placement appears to have been too low by several percent. The reduction of this system was further plagued by a several pixel shift in the cross disperser position between frames. There was no arc image for the shifted images, and thus combining the frames in order to improve the spectral signal to noise was problematic. There may be some systematic errors in the resulting analysis.
|PREVIOUS QSO| |NEXT QSO| | QSO LISTING | |TABLE OF CONTENTS| |CWC HOME|