HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION
In this paper we describe a new approach for millimeter Very Long Baseline Interferometry (mm-VLBI) calibration that provides bona-fide astrometric alignment of the millimeter-wavelength images from a single source, for the measurement of frequency-dependent effects, such as "core-shifts"...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/378274 |
| Acceso en línea: | http://hdl.handle.net/10261/378274 |
| Access Level: | acceso abierto |
| Palabra clave: | Astrometry Quasars: individual (BL-Lac) Radio continuum: galaxies Techniques: interferometric |
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HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATIONDodson, RichardRioja, María J.Molina, S.N.Gómez Fernández, José L.AstrometryQuasars: individual (BL-Lac)Radio continuum: galaxiesTechniques: interferometricIn this paper we describe a new approach for millimeter Very Long Baseline Interferometry (mm-VLBI) calibration that provides bona-fide astrometric alignment of the millimeter-wavelength images from a single source, for the measurement of frequency-dependent effects, such as "core-shifts" near the black hole of active galactic nucleus jets. We achieve our astrometric alignment by solving first for the ionospheric (dispersive) contributions using wide-band centimeter-wavelength observations. Second, we solve for the tropospheric (non-dispersive) contributions by using fast frequency-switching at the target millimeter-wavelengths. These solutions can be scaled and transferred from low frequency to the high frequency. To complete the calibration chain an additional step is required to remove a residual constant phase offset on each antenna. The result is an astrometric calibration and the measurement of the core-shift between 22 and 43 GHz for the jet in BL Lacertae to be -8 ±5, 20 ±6 μas, in R.A. and decl., respectively. By comparison to conventional phase referencing at centimeter-wavelengths we are able to show that this core shift at millimeter-wavelengths is significantly less than what would be predicted by extrapolating the low-frequency result, which closely followed the predictions of the Blandford & Kö nigl conical jet model. As such it would be the first demonstration for the association of the VLBI core with a recollimation shock, normally hidden at low frequencies due to the optical depth, which could be responsible for the γ-ray production in blazar jets. © 2017. The American Astronomical SocietyWe would like to especially acknowledge the numerous conversations with Richard Porcas about the best approaches for the analysis, and the referee for comments that improved the paper. The work at IAA-CSIC is supported by the Spanish Ministerio de Economía y Competitividad grant AYA2013- 40825-P. The VLBA is operated by National Radio Astronomy Observatory and is a facility of the National Science Foundation operated under cooperative agreement with Associated Universities Inc.Peer reviewedAmerican Astronomical SocietyMinisterio de Economía y Competitividad (España)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2025202520172025info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Postprintinfo:eu-repo/semantics/acceptedVersionhttp://hdl.handle.net/10261/378274reponame: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/10.3847/1538-4357/834/2/177Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3782742026-05-22T06:33:51Z |
| dc.title.none.fl_str_mv |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| title |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| spellingShingle |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION Dodson, Richard Astrometry Quasars: individual (BL-Lac) Radio continuum: galaxies Techniques: interferometric |
| title_short |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| title_full |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| title_fullStr |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| title_full_unstemmed |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| title_sort |
HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD for MULTI-FREQUENCY CALIBRATION |
| dc.creator.none.fl_str_mv |
Dodson, Richard Rioja, María J. Molina, S.N. Gómez Fernández, José L. |
| author |
Dodson, Richard |
| author_facet |
Dodson, Richard Rioja, María J. Molina, S.N. Gómez Fernández, José L. |
| author_role |
author |
| author2 |
Rioja, María J. Molina, S.N. Gómez Fernández, José L. |
| author2_role |
author author author |
| dc.contributor.none.fl_str_mv |
Ministerio de Economía y Competitividad (España) Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72] |
| dc.subject.none.fl_str_mv |
Astrometry Quasars: individual (BL-Lac) Radio continuum: galaxies Techniques: interferometric |
| topic |
Astrometry Quasars: individual (BL-Lac) Radio continuum: galaxies Techniques: interferometric |
| description |
In this paper we describe a new approach for millimeter Very Long Baseline Interferometry (mm-VLBI) calibration that provides bona-fide astrometric alignment of the millimeter-wavelength images from a single source, for the measurement of frequency-dependent effects, such as "core-shifts" near the black hole of active galactic nucleus jets. We achieve our astrometric alignment by solving first for the ionospheric (dispersive) contributions using wide-band centimeter-wavelength observations. Second, we solve for the tropospheric (non-dispersive) contributions by using fast frequency-switching at the target millimeter-wavelengths. These solutions can be scaled and transferred from low frequency to the high frequency. To complete the calibration chain an additional step is required to remove a residual constant phase offset on each antenna. The result is an astrometric calibration and the measurement of the core-shift between 22 and 43 GHz for the jet in BL Lacertae to be -8 ±5, 20 ±6 μas, in R.A. and decl., respectively. By comparison to conventional phase referencing at centimeter-wavelengths we are able to show that this core shift at millimeter-wavelengths is significantly less than what would be predicted by extrapolating the low-frequency result, which closely followed the predictions of the Blandford & Kö nigl conical jet model. As such it would be the first demonstration for the association of the VLBI core with a recollimation shock, normally hidden at low frequencies due to the optical depth, which could be responsible for the γ-ray production in blazar jets. © 2017. The American Astronomical Society |
| publishDate |
2017 |
| dc.date.none.fl_str_mv |
2017 2025 2025 2025 |
| dc.type.none.fl_str_mv |
info:eu-repo/semantics/article http://purl.org/coar/resource_type/c_6501 Postprint info:eu-repo/semantics/acceptedVersion |
| format |
article |
| status_str |
acceptedVersion |
| dc.identifier.none.fl_str_mv |
http://hdl.handle.net/10261/378274 |
| url |
http://hdl.handle.net/10261/378274 |
| 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/10.3847/1538-4357/834/2/177 Sí |
| dc.rights.none.fl_str_mv |
info:eu-repo/semantics/openAccess |
| eu_rights_str_mv |
openAccess |
| dc.publisher.none.fl_str_mv |
American Astronomical Society |
| publisher.none.fl_str_mv |
American Astronomical Society |
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reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC instname:Consejo Superior de Investigaciones Científicas (CSIC) |
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Consejo Superior de Investigaciones Científicas (CSIC) |
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DIGITAL.CSIC. Repositorio Institucional del CSIC |
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DIGITAL.CSIC. Repositorio Institucional del CSIC |
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