Peculiar Broad Absorption Line Quasars Found in The Digitized Palomar Observatory Sky Survey

July 2003 • 2003AJ....126...53B

Authors • Brunner, Robert J. • Hall, Patrick B. • Djorgovski, S. George • Gal, R. R. • Mahabal, A. A. • Lopes, P. A. A. • de Carvalho, R. R. • Odewahn, S. C. • Castro, S. • Thompson, D. • Chaffee, F. • Darling, J. • Desai, V.

Abstract • With the recent release of large (i.e., >~100 million objects), well-calibrated photometric surveys, such as Digitized Palomar Observatory Sky Survey (DPOSS), Two Micron All Sky Survey, and Sloan Digital Sky Survey, spectroscopic identification of important targets is no longer a simple issue. In order to enhance the returns from a spectroscopic survey, candidate sources are often preferentially selected to be of interest, such as brown dwarfs or high-redshift quasars. This approach, while useful for targeted projects, risks missing new or unusual species. We have, as a result, taken the alternative path of spectroscopically identifying interesting sources with the sole criterion being that they are in low-density areas of the g-r and r-i color space defined by DPOSS. In this paper, we present three peculiar broad absorption line quasars that were discovered during this spectroscopic survey, demonstrating the efficacy of this approach. PSS J0052+2405 is an iron low-ionization broad absorption line (LoBAL) quasar at a redshift z=2.4512+/-0.0001 with very broad absorption from many species. PSS J0141+3334 is a reddened LoBAL quasar at z=3.005+/-0.005 with no obvious emission lines. PSS J1537+1227 is an iron LoBAL at a redshift of z=1.212+/-0.007 with strong narrow Mg II and Fe II emission. Follow-up high-resolution spectroscopy of these three quasars promises to improve our understanding of BAL quasars. The sensitivity of particular parameter spaces, in this case a two-color space, to the redshift of these three sources is dramatic, raising questions about traditional techniques of defining quasar populations for statistical analysis.

Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

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Vandana Desai

Senior Scientist