A Possible Explanation

The results are consistent, in the disk-wind scenario, if NAL gas appears to arise from a geometrical selection effect. That is, at low inclination ("small i"), the radio-jet is pointed toward the observer (giving R_c~1 and flat radio spectral index) and the wind velocity disperion along the line of sight is relatively small (giving a narrow CIV emission line).
If we hypothesize that the gas producing NALs is present in all QSOs, a possible explanation for the lack of detected NALs in low inclination QSOs is either that the NAL gas is not intercepted or that the optical depth of the gas is too small.

Last modified: Fri Feb 4 14:44:53 EST 2000