New observations of the absorption spectrum of PKS 0237-23 and their implications for the origin of quasar absorption lines.
Abstract
The QSO PKS 0237-23 has been observed with the University College London image photon-counting system (IPCS) at the coude' focus of the Hale telescope. Six observations made over 3 years have been combined to give high-resolution (0.7 A) spectral coverage from A3700 to A4300. Wavelengths and equivalent widths of 193 absorption lines in this spectral region have been tabulated. Most of the lines are identified in 45 redshift systems based on C iv doublets. Eleven of these have been labeled "certain," 12 have been labeled "probable," and 22 have been called "possible." A large statistical excess of these systems shows the Si ii Al 533 excited fine- structure transition. The 45 C iv doublets have a nonuniform distribution in red shift; this nonuniformity is apparently caused by a peak at z 1.65 with a width of 5000 km -i An analysis of the splittings between C iv redshifts shows an excess of small splittings, Av 150 km s -1, and an excess at Av 1800 km -1 The excess of small splittings may be due to a continuum of splittings less than Av 200 km s . If the other peak is due to absorption-line locking, the only line pair which could account for it comprises Lfl and 0 vi A 1031. The implications of absorption systems with Zem - Zabs > 0.5 which show excited fine-structure lines are discussed in terms of the origin of the systems. Subject headings: line identifications - quasars
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1978
- DOI:
- 10.1086/155965
- Bibcode:
- 1978ApJ...220..772B
- Keywords:
-
- Absorption Spectra;
- Astronomical Spectroscopy;
- Line Spectra;
- Quasars;
- Red Shift;
- Autocorrelation;
- Carbon;
- Silicon;
- Astronomy;
- Absorption Lines:Quasars;
- Quasars: Line Identifications