Dual-frequency VLBI study of Centaurus A on sub-parsec scales. The highest-resolution view of an extragalactic jet

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dc.contributor.authorMüller, C.
dc.contributor.authorKadler, M.
dc.contributor.authorOjha, R.
dc.contributor.authorWilms, J.
dc.contributor.authorBöck, M.
dc.contributor.authorEdwards, P. G.
dc.contributor.authorFromm, C. M.
dc.contributor.authorHase, H.
dc.contributor.authorHoriuchi, S.
dc.contributor.authorKatz, U.
dc.contributor.authorLovell, J. E. J.
dc.contributor.authorPlötz, C.
dc.contributor.authorPursimo, T.
dc.contributor.authorRichers, S.
dc.contributor.authorRos, E.
dc.contributor.authorRothschild, R. E.
dc.contributor.authorTaylor, G. B.
dc.contributor.authorTingay, S. J.
dc.contributor.authorZensus, J. A.
dc.date.accessioned2020-04-01T14:00:04Z
dc.date.available2020-04-01T14:00:04Z
dc.date.issued2011-05-20
dc.description.abstractContext. Centaurus A is the closest active galactic nucleus. High resolution imaging using Very Long Baseline Interferometry (VLBI) enables us to study the spectral and kinematic behavior of the radio jet–counterjet system on sub-parsec scales, providing essential information for jet emission and formation models. Aims. Our aim is to study the structure and spectral shape of the emission from the central-parsec region of Cen A. Methods. As a target of the Southern Hemisphere VLBI monitoring program TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry), VLBI observations of Cen A are made regularly at 8.4 and 22.3 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, and South Africa. Results. The first dual-frequency images of this source are presented along with the resulting spectral index map. An angular resolution of 0.4 mas × 0.7 mas is achieved at 8.4 GHz, corresponding to a linear scale of less than 0.013 pc. Hence, we obtain the highest resolution VLBI image of Cen A, comparable to previous space-VLBI observations. By combining with the 22.3 GHz image, which has been taken without contributing transoceanic baselines at somewhat lower resolution, we present the corresponding dual-frequency spectral index distribution along the sub-parsec scale jet revealing the putative emission regions for recently detected γ-rays from the core region by Fermi/LAT. Conclusions. We resolve the innermost structure of the milliarcsecond scale jet and counterjet system of Cen A into discrete components. The simultaneous observations at two frequencies provide the highest resolved spectral index map of an AGN jet allowing us to identify multiple possible sites as the origin of the high energy emission.en_US
dc.description.sponsorshipWe acknowledge partial funding from the Bundesministerium für Wirtschaft und Technologie under Deutsches Zentrum für Luft- und Raumfahrt grant 50 OR 0808 and from the European Commission under contract number ITN 215212 “Black Hole Universe”. This research was funded in part by NASA through Fermi Guest Investigator grant NNH09ZDA001N. This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. E.R. acknowledges partial support by the Spanish MICINN through grant AYA2009-13036-C02-02. The Long Baseline Array is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. We thank the referee, D. L. Jauncey, for insightful comments which helped us to improve the manuscripten_US
dc.description.urihttps://www.aanda.org/articles/aa/abs/2011/06/aa16605-11/aa16605-11.htmlen_US
dc.format.extent4 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2ob98-jfrf
dc.identifier.citationDual-frequency VLBI study of Centaurus A on sub-parsec scales - The highest-resolution view of an extragalactic jet C. Müller, M. Kadler, R. Ojha, J. Wilms, M. Böck, P. G. Edwards, C. M. Fromm, H. Hase, S. Horiuchi, U. Katz, J. E. J. Lovell, C. Plötz, T. Pursimo, S. Richers, E. Ros, R. E. Rothschild, G. B. Taylor, S. J. Tingay and J. A. Zensus A&A, 530 (2011) L11 DOI: https://doi.org/10.1051/0004-6361/201116605en_US
dc.identifier.urihttps://doi.org/10.1051/0004-6361/201116605
dc.identifier.urihttp://hdl.handle.net/11603/17787
dc.identifier.urihttp://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2011A%26A...530L..11M
dc.identifier.urihttps://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Search&refcode=2011A%26A...530L..11M
dc.language.isoen_USen_US
dc.publisherEDP sciencesen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Physics Department Collection
dc.relation.ispartofUMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
dc.relation.ispartofUMBC Faculty Collection
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rights© ESO 2011
dc.titleDual-frequency VLBI study of Centaurus A on sub-parsec scales. The highest-resolution view of an extragalactic jeten_US
dc.typeTexten_US

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