We have optically identified a sample of 56 featureless continuum objects without significant proper motion from the 2dF QSO Redshift Survey ( 2QZ ) .
The steep number–magnitude relation of the sample , n ( b _ { J } ) \propto 10 ^ { 0.7 b _ { J } } , is similar to that derived for QSOs in the 2QZ and inconsistent with any population of Galactic objects .
Follow up high resolution , high signal-to-noise , spectroscopy of five randomly selected objects confirms the featureless nature of these sources .
Assuming the objects in the sample to be largely featureless AGN , and using the QSO evolution model derived for the 2QZ , we predict the median redshift of the sample to be z = 1.1 .
This model also reproduces the observed number-magnitude relation of the sample using a renormalisation of the QSO luminosity function , \Phi ^ { * } = \Phi ^ { * } _ { \sc qso } / 66 \simeq 1.65 \times 10 ^ { -8 } mag ^ { -1 } Mpc ^ { -3 } .
Only \sim 20 per cent of the objects have a radio flux density of S _ { 1.4 } > 3 mJy , and further VLA observations at 8.4 GHz place a 5 \sigma limit of S _ { 8.4 } < 0.2 mJy on the bulk of the sample .
We postulate that these objects could form a population of radio-weak AGN with weak or absent emission lines , whose optical spectra are indistinguishable from those of BL Lac objects .