Robert H. Becker
University of California at Davis and Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory (bob@igpp.llnl.gov)
Michael D. Gregg
Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory (gregg@igpp.llnl.gov)
Isobel M. Hook
European Southern Observatory (imh@eso.org)
Richard G. McMahon
Institute of Astronomy, Cambridge (rgm@ast.cam.ac.uk)
Richard L. White
Space Telescope Science Institute (rlw@stsci.edu)
David J. Helfand
Columbia Astrophysics Laboratory (djh@astro.columbia.edu)
We have discovered two low-ionization broad absorption line quasars in programs to obtain optical spectra for radio-selected quasar candidates from the VLA FIRST Survey (Becker, White, & Helfand 1995). Both belong to the extremely rare class of BAL QSOs that exhibit narrow absorption lines from metastable excited levels of Fe II and Fe III. Until now, there was just a single object in this class, 0059-2735 (Hazard et al. 1987). In addition, one of our new objects is the first known radio-loud BAL QSO. The properties of these three unusual objects suggest a trend of increasing radio luminosity with the amount of absorption to the quasar, and are perhaps transition objects between radio-loud and radio-quiet quasars.
The two new objects are from a radio-selected sample comprising less than 200 quasars; one is heavily attenuated at optical wavelengths in the observed frame. These objects would be easily overlooked by most optical QSO searches; their abundance in the radio sample suggests that they may be representatives of a largely undetected component of the quasar population, perhaps as numerous as ordinary low-ionization BAL QSOs which constitute 1-2% of all QSOs.
Published in
The Astrophysical Journal (Letters), 479, L93 (1997)
© 1997 The American Astronomical Society
Keywords: quasars: radio selected -- quasars - galaxies: spectrophotometry
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