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The Parkes quarter-Jansky flat-spectrum sample 2. New Optical Spectra and Redshift Measurements | | I. M. Hook
; P. A. Shaver
; C. A. Jackson
; J. V. Wall
; K. I. Kellermann
; | | Date: |
17 Dec 2002 | | Journal: | Astron.Astrophys. 399 (2003) 469-488 | | Subject: | astro-ph | | Affiliation: | U. Oxford), P. A. Shaver (ESO), C. A. Jackson (ANU), J. V. Wall (U. Oxford) and K. I. Kellermann (NRAO | | Abstract: | We present optical spectra and redshift measurements for 178 flat-spectrum objects from the Parkes quarter-Jansky flat-spectrum sample. These spectra were obtained in order to compile a complete sample of quasars for use in a study of quasar evolution. We present a composite optical spectrum made from the subset of 109 quasars that have flux densities in the range 0.25Jy < S(2.7GHz)< 0.5Jy, and make a comparison with a composite for radio-quiet QSOs from the Large Bright Quasar Survey. Our large sample of radio-loud quasars allows us to strengthen previous reports that the Ly-alpha and CIV emission lines have larger equivalent width in radio-loud quasars than radio-quiet QSOs to greater than the 3-sigma level. However we see no significant difference in the equivalent widths of CIII] or MgII. We also show that the flux decrements across the Lyman-alpha line (D_A) measured from these spectra show the same trend with redshift as for optically selected QSOs. | | Source: | arXiv, astro-ph/0212386 | | Services: | Forum | Review | PDF | Favorites | |
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