The AGN content of the FBS

Thirty-four FBS objects are listed as QSOs in the eight edition of the Véron-Cetty & Véron catalogue [55]. Two more (FBS 1102+347 and 1147+673) have been shown to be QSOs [25] and six have been identified in the present paper (Table 2). There are therefore 42 known QSOs in the FBS, 41 being at high galactic latitude ($\vert b \vert$ > 30$^\circ$).

At high galactic latitudes, all FBS objects associated with a ROSAT RASS-BSC source have been identified. Among them, there are 25 QSOs with known z, and one without, altogether 26. As about 60% of all PG QSOs are RASS sources, and assuming that this is true for the FBS QSOs, we should have a total of about 43 QSOs in the FBS catalogue (including the one without known z). This suggests that the number of QSOs still to be found in the FBS catalogue is very small as 42 have already been found.

All 114 AGNs from the PG survey have been observed at 5GHz with the VLA [28]; thirty five (30%) have been detected with a flux density larger than 3mJy. The same fraction (12/40) of the known FBS QSOs have been detected in the NVSS survey, suggesting that the number of QSOs in the as yet spectroscopically unobserved FBS objects is small and probably cannot exceed about 10, as the fraction of radio-detected QSOs would then drop below 25% and be significantly lower than the corresponding fraction for the PG survey.