NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-07-24 T03:03:45 PDT
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For refcode 2013A&A...560A..23L:
Retrieve 42 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2013A&A...560A..23L Exploring the bulk of the BL Lacertae object population. I. Parsec-scale radio structures Liuzzo, E.; Giroletti, M.; Giovannini, G.; Boccardi, B.; Tamburri, S.; Taylor, G. B.; Casadio, C.; Kadler, M.; Tosti, G.; Mignano, A. Abstract. Context. The advent of Fermi is changing our understanding on the radio and gamma-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the gamma-ray band. However, since they are relatively weak radio sources, most of their parsec-scale structure and their multifrequency properties are poorly understood and/or have not been investigated in a systematic fashion. Aims: Our main goal is to analyze the radio and gamma-ray emission properties of a sample of 42 BL Lacs selected, for the first time in the literature, with no constraint on their radio and gamma-ray emission. Methods: Thanks to new Very Long Baseline Array observations at 8 and 15 GHz for the whole sample, we present fundamental parameters here such as radio flux densities, spectral index information, and parsec-scale structure. Moreover, we search for gamma-ray counterparts using data reported in the Second Catalog of Fermi Gamma-ray sources. Results: Parsec-scale radio emission is observed in the majority of the sources at both frequencies. Gamma-ray counterparts are found for 14/42 sources. Conclusions: The comparison between our results in radio and gamma-ray bands points out the presence of a large number of faint BL Lacs showing "non-classical" properties such as low source compactness, core dominance, no gamma-ray emission, and steep radio spectral indexes. A deeper multiwavelength analysis will be needed. The calibrated uv and FITS files are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A23 Key words: radio continuum: galaxies, galaxies: active, galaxies: jets
Retrieve 42 NED objects in this reference.
Please click here for ADS abstract

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