Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures

Context. The advent of Fermi is changing our understanding on the radio and γ-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the γ-ray band. However, since they are relatively weak radio sources, most of their parsec-scale...

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Autores: Liuzzo, Elisabetta, Giroletti, M., Giovannini, G., Boccardi, B., Tamburri, S., Taylor, G. B., Casadio, Carolina, Kadler, M., Tosti, G., Mignano, A.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2013
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/404666
Acceso en línea:http://hdl.handle.net/10261/404666
Access Level:acceso abierto
Palabra clave:Galaxies: active
Galaxies: jets
Radio continuum: galaxies
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spelling Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structuresLiuzzo, ElisabettaGiroletti, M.Giovannini, G.Boccardi, B.Tamburri, S.Taylor, G. B.Casadio, CarolinaKadler, M.Tosti, G.Mignano, A.Galaxies: activeGalaxies: jetsRadio continuum: galaxiesContext. The advent of Fermi is changing our understanding on the radio and γ-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the γ-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 γ-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 γ-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 γ-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. © ESO, 2013.This work was supported by contributions of European Union, Valle D′Aosta Region, and the Italian Minister for Work and Welfare. We acknowledge the financial contribution from grant PRIN-INAF-2011. The authors wish to thank Prof. Enrico Massaro for his contribution in the early stages of this project. This research made use of the NASA/IPAC Extragalactic Data Base (NED), which is operated by the JPL, California Institute of Technology, under contract with the National Aeronautics and Space Administration. G.B.T. thanks NASA for support under FERMI grant NNX12AO75G.Peer reviewedEDP SciencesEuropean CommissionNASAMinistero del Lavoro e delle Politiche SocialiConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]202520252013info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/404666reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://dx.doi.org/10.1051/0004-6361/201322144Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/4046662026-05-22T06:33:51Z
dc.title.none.fl_str_mv Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
title Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
spellingShingle Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
Liuzzo, Elisabetta
Galaxies: active
Galaxies: jets
Radio continuum: galaxies
title_short Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
title_full Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
title_fullStr Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
title_full_unstemmed Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
title_sort Exploring the bulk of the BL Lacertae object population: I. Parsec-scale radio structures
dc.creator.none.fl_str_mv Liuzzo, Elisabetta
Giroletti, M.
Giovannini, G.
Boccardi, B.
Tamburri, S.
Taylor, G. B.
Casadio, Carolina
Kadler, M.
Tosti, G.
Mignano, A.
author Liuzzo, Elisabetta
author_facet Liuzzo, Elisabetta
Giroletti, M.
Giovannini, G.
Boccardi, B.
Tamburri, S.
Taylor, G. B.
Casadio, Carolina
Kadler, M.
Tosti, G.
Mignano, A.
author_role author
author2 Giroletti, M.
Giovannini, G.
Boccardi, B.
Tamburri, S.
Taylor, G. B.
Casadio, Carolina
Kadler, M.
Tosti, G.
Mignano, A.
author2_role author
author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv European Commission
NASA
Ministero del Lavoro e delle Politiche Sociali
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxies: active
Galaxies: jets
Radio continuum: galaxies
topic Galaxies: active
Galaxies: jets
Radio continuum: galaxies
description Context. The advent of Fermi is changing our understanding on the radio and γ-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the γ-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 γ-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 γ-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 γ-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. © ESO, 2013.
publishDate 2013
dc.date.none.fl_str_mv 2013
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/404666
url http://hdl.handle.net/10261/404666
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://dx.doi.org/10.1051/0004-6361/201322144
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.812429

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