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Paper: Four New BL Lac Surveys: Sampling New Populations
Volume: 159, BL Lac Phenomenon
Page: 499
Authors: Laurent-Muehleisen, S. A.; Becker, R. H.; Brinkmann, W.; Siebert, J.; Feigelson, E. D.; Kollgaard, R. I.; Schmidt, G. D.; Smith, P. S.
Abstract: The advent of large area deep radio and X-ray sky surveys is leading to the creation of many new BL Lac samples. In particular, the Rosat All-Sky (RASS) and the VLA's FIRST (Faint Images of the Radio Sky at Twenty centimeters) surveys are proving to be rich sources of new BL Lacs. We will discuss the methods used in several independent BL Lac searches based on these surveys, including the RASS-Green Bank, RASS-FIRST, and FIRST Flat Spectrum samples in addition to the large sample of serendipitous BL Lacs discovered in the course of the FIRST bright quasar survey. We will present the multiwavelength properties of these objects, including their broadband radio, optical and X-ray flux distributions, and their optical emission line and polarization properties. Comparison of these properties with those of previously known BL Lacs clearly points to the existence of a large previously unrecognized population of intermediate BL Lacs: objects with characteristics intermediate between those exhibited by Low and High energy peaked BL Lacs (LBLs and HBLs, respectively). We will also discuss what implications these objects have for the X-ray-leading vs. radio-leading models which attempt to unify the BL Lac population.
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