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VLBI Observations of Gamma-Ray-Quiet Active Galactic Nuclei: Comparing Radio-Core Brightness Temperatures


Tingay, SJ and Murphy, DW and Lovell, JEJ and Costa, ME and McCulloch, PM and Edwards, PG and Jauncey, DL and Reynolds, JE and Tzioumis, AK and King, EA and Jones, DL and Preston, RA and Meier, DL and van Ommen, TD and Nicolson, GD and Quick, JFH, VLBI Observations of Gamma-Ray-Quiet Active Galactic Nuclei: Comparing Radio-Core Brightness Temperatures, The Astrophysical Journal, 497, (2) pp. 594-600. ISSN 0004-637X (1998) [Refereed Article]

DOI: doi:10.1086/305494


We present VLBI and Australia Telescope Compact Array images and derive source-frame radio-core brightness temperatures for three prominent, flat-spectrum extragalactic radio sources, notable because they have not been detected as gamma-ray sources with the EGRET instrument. Radio-core brightness temperatures are discussed as an indicator of relativistic beaming. A comparison of source-frame radio-core brightness temperatures for EGRET-identified and gammaray-quiet, radio-loud AGNs shows that a wide range in beaming properties is likely to exist, independent of the level of gamma-ray emission. This comparison suggests that, although there is a strong relationship between radio emission and gamma-ray emission in EGRET-identified AGNs, and many EGRET-identified AGNs show evidence for relativistic beaming, there is little evidence for a one-to-one correspondence between the strength of gamma-ray emission and the degree of beaming of the radio emission. © 1998. The American Astronomical Society. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Lovell, JEJ (Dr Jim Lovell)
UTAS Author:Costa, ME (Dr Marco Costa)
UTAS Author:McCulloch, PM (Professor Peter McCulloch)
ID Code:13561
Year Published:1998
Web of Science® Times Cited:28
Deposited By:Physics
Deposited On:1998-08-01
Last Modified:2011-08-08

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