A Sample of Low‐Redshift BL Lacertae Objects. I. The Radio Data

Abstract

ABSTRACTWe present a new sample of 30 nearby (z < 0.2) BL Lacs, selected to studythe nuclear as well as the large scale properties of low power radio sources. In thisfirst paper, we show and discuss new radio data taken with the VLA (19 objectsat 1.4 GHz, either in A or C configuration, or both) as well as with the VLBA(15 sources at 5 GHz). On the kiloparsec scale, all objects exhibit a compact coreand a variety of radio morphologies (jets, halos, secondary compact components).On the parsec scale, we find weak cores and a few short, one-sided, jets. From thejet/counter-jet ratio, core dominance, and synchrotron self Compton model weestimate the intrinsic orientation and velocity ofthe jets. The resulting propertiesof BL Lacs are similar to those of a parent population composed of FR I radiogalaxies. Subject headings: galaxies: active — galaxies: nuclei — galaxies: jets — BLLacertae objects: general — radio continuum: galaxies1. INTRODUCTIONEver since the first suggestion of a possible unification of radio sources (e.g., Orr &Browne 1982), the viability for a comprehensive view of Active Galactic Nuclei (AGN) hasbeen actively debated. A major achievement is the formulation of a scheme in which BL