Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421

In this work, we interpret and discuss the time variable rotation measure (RM) found, for the first time over a 1-yr period, in the core region of a blazar. These results are based on a 1-yr, multifrequency (15, 24 and 43 GHz) Very Long Baseline Array (VLBA) monitoring of the TeV blazar Markarian 42...

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Autores: Lico, Rocco, Gómez Fernández, José L., Asada, Keiichi, Fuentes, Antonio
Tipo de documento: artigo
Estado:Versão publicada
Data de publicação:2017
País:España
Recursos:Consejo Superior de Investigaciones Científicas (CSIC)
Repositório:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/369681
Acesso em linha:http://hdl.handle.net/10261/369681
Access Level:Acceso aberto
Palavra-chave:Galaxies: active
BL Lacertae objects: individual: Mrk 421
Galaxies: jets
Galaxies: magnetic fields
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spelling Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421Lico, RoccoGómez Fernández, José L.Asada, KeiichiFuentes, AntonioGalaxies: activeBL Lacertae objects: individual: Mrk 421Galaxies: jetsGalaxies: magnetic fieldsIn this work, we interpret and discuss the time variable rotation measure (RM) found, for the first time over a 1-yr period, in the core region of a blazar. These results are based on a 1-yr, multifrequency (15, 24 and 43 GHz) Very Long Baseline Array (VLBA) monitoring of the TeV blazar Markarian 421 (Mrk 421). We investigate the Faraday screen properties and its location with respect to the jet emitting region. Given that the 43-GHz radio core flux density and the RMtime evolution suggest a similar trend, we explore the possible connection between the RM and the accretion rate. Among the various scenarios that we explore, the jet sheath is the most promising candidate for being the main source of Faraday rotation. During the 1-yr observing period, the RM trend shows two sign reversals, which may be qualitatively interpreted within the context of the magnetic tower models. We invoke the presence of two nested helical magnetic fields in the relativistic jet with opposite helicities, whose relative contribution produce the observed RM values. The inner helical field has the poloidal component (B) oriented in the observer's direction and produces a positive RM, while the outer helical field, with B in the opposite direction, produces a negative RM. We assume that the external helical field dominates the contribution to the observed RM, while the internal helical field dominates when a jet perturbation arises during the second observing epoch. Being the intrinsic polarization angle parallel to the jet axis, a pitch angle of the helical magnetic field ϕ ≳ 70° is required. Additional scenarios are also considered to explain the observed RM sign reversals. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical SocietyWe thank the anonymous referee for valuable comments and suggestions that improved the quality of this manuscript. RL gratefully acknowledges the financial support and the kind hospitality from the Instituto de Astrof´ısica de Andalucia (IAA-CSIC) in Granada. This work is based on observations obtained through the BG207 VLBA project, which makes use of the Swinburne University of Technology software CORRELATOR, developed as part of the Australian Major National Research Facilities Programme and operated under license (Deller et al. 2011). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge financial support from grants PRIN-INAF-2014 and AYA2013-40825-P. This study makes use of 43 GHz VLBA data from the VLBA-BU Blazar Monitoring Program (VLBA-BUBLAZAR; http://www.bu.edu/blazars/VLBAproject.html), funded by NASA through the Fermi Guest Investigator Program. The VLBA is an instrument of the Long Baseline Observatory. The Long Baseline Observatory is a facility of the National Science Foundation operated by Associated Universities, IncOxford University PressIstituto Nazionale di AstrofisicaMinisterio de Economía y Competitividad (España)NASAConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2024202420172024info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/369681reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/MINECO//AYA2013-40825-Phttp://dx.doi.org/10.1093/mnras/stx960Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3696812026-05-22T06:33:51Z
dc.title.none.fl_str_mv Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
title Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
spellingShingle Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
Lico, Rocco
Galaxies: active
BL Lacertae objects: individual: Mrk 421
Galaxies: jets
Galaxies: magnetic fields
title_short Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
title_full Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
title_fullStr Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
title_full_unstemmed Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
title_sort Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
dc.creator.none.fl_str_mv Lico, Rocco
Gómez Fernández, José L.
Asada, Keiichi
Fuentes, Antonio
author Lico, Rocco
author_facet Lico, Rocco
Gómez Fernández, José L.
Asada, Keiichi
Fuentes, Antonio
author_role author
author2 Gómez Fernández, José L.
Asada, Keiichi
Fuentes, Antonio
author2_role author
author
author
dc.contributor.none.fl_str_mv Istituto Nazionale di Astrofisica
Ministerio de Economía y Competitividad (España)
NASA
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxies: active
BL Lacertae objects: individual: Mrk 421
Galaxies: jets
Galaxies: magnetic fields
topic Galaxies: active
BL Lacertae objects: individual: Mrk 421
Galaxies: jets
Galaxies: magnetic fields
description In this work, we interpret and discuss the time variable rotation measure (RM) found, for the first time over a 1-yr period, in the core region of a blazar. These results are based on a 1-yr, multifrequency (15, 24 and 43 GHz) Very Long Baseline Array (VLBA) monitoring of the TeV blazar Markarian 421 (Mrk 421). We investigate the Faraday screen properties and its location with respect to the jet emitting region. Given that the 43-GHz radio core flux density and the RMtime evolution suggest a similar trend, we explore the possible connection between the RM and the accretion rate. Among the various scenarios that we explore, the jet sheath is the most promising candidate for being the main source of Faraday rotation. During the 1-yr observing period, the RM trend shows two sign reversals, which may be qualitatively interpreted within the context of the magnetic tower models. We invoke the presence of two nested helical magnetic fields in the relativistic jet with opposite helicities, whose relative contribution produce the observed RM values. The inner helical field has the poloidal component (B) oriented in the observer's direction and produces a positive RM, while the outer helical field, with B in the opposite direction, produces a negative RM. We assume that the external helical field dominates the contribution to the observed RM, while the internal helical field dominates when a jet perturbation arises during the second observing epoch. Being the intrinsic polarization angle parallel to the jet axis, a pitch angle of the helical magnetic field ϕ ≳ 70° is required. Additional scenarios are also considered to explain the observed RM sign reversals. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
publishDate 2017
dc.date.none.fl_str_mv 2017
2024
2024
2024
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/10261/369681
url http://hdl.handle.net/10261/369681
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/MINECO//AYA2013-40825-P
http://dx.doi.org/10.1093/mnras/stx960
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Oxford University Press
publisher.none.fl_str_mv Oxford University Press
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 15.811543

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