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TANAMI: Tracking active galactic nuclei with austral millarsecond interferometry


Ojha, R and Kadler, M and Bock, M and Booth, R and Dutka, MS and Edwards, PG and Fey, AL and Fuhrmann, L and Gaume, RA and Hase, H and Horiuchi, S and Jauncey, DL and Johnson, KJ and Katz, U and Lister, M and Lovell, JEJ and Mueller, C and Plotz, C and Quick, JFH and Ros, E and Taylor, GB and Thompson, DJ and Tingay, SJ and Tosti, G and Tzioumis, AK and Wilms, J and Zensus, JA, TANAMI: Tracking active galactic nuclei with austral millarsecond interferometry, Astronomy and Astrophysics, 519, (Sept) EJ ISSN 0004-6361 (2010) [Refereed Article]

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Copyright © EDP Sciences, 2010

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DOI: doi:10.1051/0004-6361/200912724


Context. A number of theoretical models vie to explain the ã-ray emission from active galactic nuclei (AGN). This was a key discovery of EGRET. With its broader energy coverage, higher resolution, wider field of view and greater sensitivity, the Large Area Telescope (LAT) of the Fermi Gamma-ray Space Telescope is dramatically increasing our knowledge of AGN ã-ray emission. However, discriminating between competing theoretical models requires quasi-simultaneous observations across the electromagnetic spectrum. By resolving the powerful parsecscale relativistic outflows in extragalactic jets and thereby allowing us to measure critical physical properties, Very Long Baseline Interferometry observations are crucial to understanding the physics of extragalactic ã-ray objects. Aims. We introduce the TANAMI program (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) which is monitoring an initial sample of 43 extragalactic jets located south of −30 degrees declination at 8.4GHz and 22GHz since 2007. All aspects of the program are discussed. First epoch results at 8.4GHz are presented along with physical parameters derived therefrom. Methods. These observations were made during 2007/2008 using the telescopes of the Australian Long Baseline Array in conjunction with Hartebeesthoek in South Africa. These data were correlated at the Swinburne University correlator. Results. We present first epoch images for 43 sources, some observed for the first time at milliarcsecond resolution. Parameters of these images as well as physical parameters derived from them are also presented and discussed. These and subsequent images from the TANAMI survey are available at Conclusions. We obtain reliable, high dynamic range images of the southern hemisphere AGN. All the quasars and BL Lac objects in the sample have a single-sided radio morphology. Galaxies are either double-sided, single-sided or irregular. About 28% of the TANAMI sample has been detected by LAT during its first three months of operations. Initial analysis suggests that when galaxies are excluded, sources detected by LAT have larger opening angles than those not detected by LAT. Brightness temperatures of LAT detections and non-detections seem to have similar distributions. The redshift distributions of the TANAMI sample and sub-samples are similar to those seen for the bright ã-ray AGN seen by LAT and EGRET but none of the sources with a redshift above 1.8 have been detected by LAT

Item Details

Item Type:Refereed Article
Keywords:galaxies: active – galaxies: jets – galaxies: nuclei – gamma rays: observations – quasars: general
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:65933
Year Published:2010
Web of Science® Times Cited:69
Deposited By:Physics
Deposited On:2010-12-10
Last Modified:2011-03-24

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