NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Dual-Frequency VLBI Study of Centaurus A on Sub-Parsec Scales: The Highest-Resolution View of an Extragalactic JetCentaurus 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-<:ounterjet 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 Millliarcsecond 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 x 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, we present the corresponding dual-frequency spectral index distribution along the sub-parsec scale jet revealing the putative emission regions for recently detected y-rays from the core region by Fermi/LAT. Conclusions. We resolve the innermost structure of the milliarcsecond scale jet and counter jet 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 up to four possible sites as the origin of the high energy emission. Key words. galaxies: active galaxies: individual (Centaurus A, NGC 5128) - galaxies: jets - techniques: high angular resolution
Document ID
20110008284
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Mueller, C.
(Erlangen-Nuernberg Univ. Bamberg, Germany)
Kadler, M.
(Erlangen-Nuernberg Univ. Bamberg, Germany)
Ojha, R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wilms, J.
(Erlangen-Nuernberg Univ. Bamberg, Germany)
Boeck, M.
(Erlangen-Nuernberg Univ. Bamberg, Germany)
Edwards, P.
(Australia Telescope National Facility Epping, Australia)
Fromm, C. M.
(Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Hase, H.
(Federal Agency for Cartography and Geodesy Frankfurt, Germany)
Horiuchi, S.
(Canberra Deep Sea Communications Complex Kingston, Australia)
Katz, U.
(Erlangen-Nuernberg Univ. Erlangen, Germany)
Lovell, J. E. J.
(Tasmania Univ. Hobart, Australia)
Ploetz, C.
(Federal Agency for Cartography and Geodesy Frankfurt, Germany)
Pursimo, T.
Richers, S.
(Erlangen-Nuernberg Univ. Bamberg, Germany)
Ros, E.
(Valencia Univ. Spain)
Rothschild, R. E.
(California Univ., San Diego La Jolla, CA, United States)
Taylor, G. B.
(New Mexico Univ. Albuquerque, NM, United States)
Tingay, S. J.
(Curtin Univ. of Technology Bentley, Australia)
Zensus, J. A.
(Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Date Acquired
August 25, 2013
Publication Date
January 28, 2011
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NNH06CC03B
CONTRACT_GRANT: 50 OR 0808
CONTRACT_GRANT: NNH09ZDA001N
CONTRACT_GRANT: ITN 215212
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available