TANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jet

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dc.contributor.authorMüller, C.
dc.contributor.authorKadler, M.
dc.contributor.authorOjha, R.
dc.contributor.authorPerucho, M.
dc.contributor.authorGrossberger, C.
dc.contributor.authorRos, E.
dc.contributor.authorWilms, J.
dc.contributor.authorBlanchard, J.
dc.contributor.authorBöck, M.
dc.contributor.authorCarpenter, B.
dc.contributor.authorDutka, M.
dc.contributor.authorEdwards, P. G.
dc.contributor.authorHase, H.
dc.contributor.authorHoriuchi, S.
dc.contributor.authorKreikenbohm, A.
dc.contributor.authorLovell, J. E. J.
dc.contributor.authorMarkowitz, A.
dc.contributor.authorPhillips, C.
dc.contributor.authorPlötz, C.
dc.contributor.authorPursimo, T.
dc.contributor.authorQuick, J.
dc.contributor.authorRothschild, R.
dc.contributor.authorSchulz, R.
dc.contributor.authorSteinbring, T.
dc.contributor.authorStevens, J.
dc.contributor.authorTrüstedt, J.
dc.contributor.authorTzioumis, A. K.
dc.date.accessioned2020-05-01T13:22:46Z
dc.date.available2020-05-01T13:22:46Z
dc.date.issued2014-10-01
dc.description.abstractContext. Centaurus A (Cen A) is the closest radio-loud active galactic nucleus. Very Long Baseline Interferometry (VLBI) enables us to study the spectral and kinematic behavior of the radio jet-counterjet system on milliarcsecond scales, providing essential information for jet emission and propagation models. Aims. In the framework of the TANAMI monitoring, we investigate the kinematics and complex structure of Cen A on subparsec scales. We have been studying the evolution of the central parsec jet structure of Cen A for over 3.5 years. The proper motion analysis of individual jet components allows us to constrain jet formation and propagation and to test the proposed correlation of increased high-energy flux with jet ejection events. Cen A is an exceptional laboratory for such a detailed study because its proximity translates to unrivaled linear resolution, where one milliarcsecond corresponds to 0.018 pc. Methods. As a target of the southern-hemisphere VLBI monitoring program TANAMI, observations of Cen A are done approximately every six months at 8.4 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, New Zealand, and South Africa, complemented by quasi-simultaneous 22.3 GHz observations. Results. The first seven epochs of high-resolution TANAMI VLBI observations at 8.4 GHz of Cen A are presented, resolving the jet on (sub-)milliarcsecond scales. They show a differential motion of the subparsec scale jet with significantly higher component speeds farther downstream where the jet becomes optically thin. We determined apparent component speeds within a range of 0.1 c to 0.3 c and identified long-term stable features. In combination with the jet-to-counterjet ratio, we can constrain the angle to the line of sight to θ ~ 12°−45°. Conclusions. The high-resolution kinematics are best explained by a spine-sheath structure supported by the downstream acceleration occurring where the jet becomes optically thin. On top of the underlying, continuous flow, TANAMI observations clearly resolve individual jet features. The flow appears to be interrupted by an obstacle causing a local decrease in surface brightness and circumfluent jet behavior. We propose a jet-star interaction scenario to explain this appearance. The comparison of jet ejection times to high X-ray flux phases yields a partial overlap of the onset of the X-ray emission and increasing jet activity, but the limited data do not support a robust correlation.en_US
dc.description.sponsorshipThe authors acknowledge the helpful discussions and suggestions by A. Lobanov and K. Mannheim, and especially thank the anonymous referee for valuable comments that improved the paper. C.M. acknowledges the support by the “Studienstiftung des Deutschen Volkes”. E.R. was partially supported by the Spanish MINECO projects AYA2009-13036-C02-02 and AYA2012-38491-C02-01 and by the Generalitat Valenciana project PROMETEO/2009/104, as well as by the COST MP0905 action “Black Holes in a Violent Universe”. M.P. acknowledges financial support by the Spanish “Ministerio de Ciencia e Innovación” (MICINN) grants AYA2010-21322-C03-01, AYA2010-21097-C03-01, and support by Universitat de València and Max-Planck-Institut für Radioastronomie. The Australian 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. This research was funded in part by NASA through Fermi Guest Investigator grants NNH09ZDA001N, NNH10ZDA001N, and NNH12ZDA001N. 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. This research made use of data from the NASA/IPAC Extragalactic Database (NED), operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration; and the SIMBAD database (operated at the CDS, Strasbourg, France)en_US
dc.description.urihttps://www.aanda.org/articles/aa/abs/2014/09/aa23948-14/aa23948-14.htmlen_US
dc.format.extent16 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m21fut-2yab
dc.identifier.citationTANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jet C. Müller, M. Kadler, R. Ojha, M. Perucho, C. Großberger, E. Ros, J. Wilms, J. Blanchard, M. Böck, B. Carpenter, M. Dutka, P. G. Edwards, H. Hase, S. Horiuchi, A. Kreikenbohm, J. E. J. Lovell, A. Markowitz, C. Phillips, C. Plötz, T. Pursimo, J. Quick, R. Rothschild, R. Schulz, T. Steinbring, J. Stevens, J. Trüstedt and A. K. Tzioumis A&A, 569 (2014) A115 DOI: https://doi.org/10.1051/0004-6361/201423948en_US
dc.identifier.urihttps://doi.org/10.1051/0004-6361/201423948
dc.identifier.urihttp://hdl.handle.net/11603/18394
dc.identifier.urihttp://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2014A%26A...569A.115M
dc.identifier.urihttps://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Search&refcode=2014A%26A...569A.115M
dc.identifier.urihttps://heasarc.gsfc.nasa.gov/xamin/xamin.jsp?bibcode=2014A%26A%2E%2E%2E569A%2E115M
dc.identifier.urihttp://vizier.u-strasbg.fr/viz-bin/VizieR?-source=J/A+A/569/A115
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 Faculty Collection
dc.relation.ispartofUMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
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 2014
dc.titleTANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jeten_US
dc.typeTexten_US

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