A search for extended line emission from broad absorption line QSOs

摘要

We have obtained Hubble Space Telescope NICMOS snapshot images of 10 broad absorption line (BAL) QSOs and four radio-quiet non-BAL QSOs to search for extended narrow-line regions. For each object, we obtained an image in the F160W filter and a narrowband image in either H alpha, H beta, or O II. We find no detections of extended narrow-line emission in the sample. We generate simulated images of QSOs with extended narrow-line regions to place limits on the amount of flux that may be present, and we conclude that BAL QSOs cannot be more than several times brighter in extended emission than typical type 2 active galactic nuclei. Spatially unresolved H alpha emission is detected in all nine objects observed in this line, which we attribute to broad H alpha emission. The five detected BAL QSOs have derived H alpha equivalent widths that are larger than those of the four non-BAL QSOs by a factor of similar to2 on average. This may point to an intrinsic difference between the rest-frame optical spectral properties of BAL and non-BAL QSOs. References: 36