The Parkes quarter-Jansky flat-spectrum sample

Abstract

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 0.25 Jy < S 2.7 GHz < 0.5 Jy, 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 Lyα and CIV emission lines have larger equivalent width in radio-loud quasars than radio-quiet QSOs to greater than the 3σ 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-α line (D A ) measured from these spectra show the same trend with redshift as for optically selected QSOs.

ESO Very Large Telescope Optical Spectroscopy of BL Lacertae Objects. II. New Redshifts, Featureless Objects, and Classification Assessments

“…2254À204: Previous optical spectroscopy ( Véron-Cetty & Véron 1993b;Hook et al 2003) of this BL Lac object from the 1 Jy sample showed completely featureless spectra. With the VLT we are able to detect faint interstellar absorptions of Ca ii kk3934, 3968 and Na i k5892, but no intrinsic or intervening spectral lines are found.…”

“…Based on EW min , we estimate z > 0:31. 0627À199: Hook et al (2003) obtained a lineless spectrum for this radio-selected BL Lac object. Our VLT spectrum, of moderate S/ N (50), shows no spectral features.…”

“…Most of these works were based on optical spectra collected with 4 m class telescopes and are therefore limited by relatively low signal-to-noise ratio (S/ N ), low spectral resolution, and limited wavelength range (e.g., Falomo et al 1993Falomo et al , 1994Stickel & Kühr 1993;Véron-Cetty & Véron 1993b;Bade et al 1994;Falomo 1996;Marchã et al 1996;Drinkwater et al 1997;Laurent-Muehleisen et al 1998;Landt et al 2001;Rector & Stocke 2001;Londish et al 2002;Carangelo et al 2003;Hook et al 2003). Recently, however, some observations with 8 m class telescopes have been carried out ( Heidt et al 2004;Sowards-Emmerd et al 2005).…”

Optical spectroscopy of BL Lacertae objects

“…Until recently, most of the work in this field has made use of 2−4 m class telescopes (e.g. Falomo et al 1993;Stickel & Kühr 1993;Véron-Cetty & Véron 1993;Bade et al 1994;Falomo et al 1994;Falomo 1996;Marchã et al 1996;Drinkwater et al 1997;Laurent-Muehleisen et al 1998;Landt et al 2001;Rector & Stocke 2001;Londish et al 2002;Hook et al 2003;Carangelo et al 2003).…”

The Cosmic Evolution of Quasars

“…As described in detail in Jackson et al (2002) we selected all flat-spectrum sources from PKSCAT90 with oi h^z Hz > -0.4, where S ex v a , yielding an initial sample of 878 sources. Imaging and spectroscopy campaigns (Jackson et al 2002;Hook et al 2003) yielded a final sample of identifications. We found that 677/878 sources had stellar host objects (quasars and BLLac objects).…”