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The Micro-arcsecond Scintillation-Induced Variability (MASIV) Survey. II. The first four epochs
Citation
Lovell, JEJ and Rickett, BJ and Macquart, JP and Jauncey, DL and Bignall, HE and Kedziora-Chudczer, L and Ojha, R and Pursimo, T and Dutka, M and Senkbeil, CE and Shabala, SS, The Micro-arcsecond Scintillation-Induced Variability (MASIV) Survey. II. The first four epochs, The Astrophysical Journal, 689, (1) pp. 108-126. ISSN 0004-637X (2008) [Refereed Article]
DOI: doi:10.1086/592485
Abstract
We report on the variability of 443 flat-spectrum, compact radio sources monitored using the VLA for 3 days in four epochs at ̃4 month intervals at 5 GHz as part of the Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey. Over half of these sources exhibited 2%-10% rms variations on timescales over 2 days. We analyzed the variations by two independent methods and find that the rms variability amplitudes of the sources correlate with the emission measure in the ionized interstellar medium along their respective lines of sight. We thus link the variations with interstellar scintillation of components of these sources, with some (unknown) fraction of the total flux density contained within a compact region of angular diameter in the range 10-50 μas. We also find that the variations decrease for high mean flux density sources and, most importantly, for high-redshift sources. The decrease in variability is probably due either to an increase in the apparent diameter of the source or to a decrease in the flux density of the compact fraction beyond z ̃2. Here we present a statistical analysis of these results, and a future paper will discuss the cosmological implications in detail. © 2008. The American Astronomical Society. All rights reserved.
Item Details
Item Type: | Refereed Article |
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Keywords: | The Micro-arcsecond Scintillation-Induced Variability (MASIV) Survey. II. The First Four Epochs |
Research Division: | Physical Sciences |
Research Group: | Astronomical sciences |
Research Field: | Solar physics |
Objective Division: | Expanding Knowledge |
Objective Group: | Expanding knowledge |
Objective Field: | Expanding knowledge in the earth sciences |
UTAS Author: | Lovell, JEJ (Dr Jim Lovell) |
UTAS Author: | Senkbeil, CE (Mr Cliff Senkbeil) |
UTAS Author: | Shabala, SS (Associate Professor Stas Shabala) |
ID Code: | 53932 |
Year Published: | 2008 |
Web of Science® Times Cited: | 94 |
Deposited By: | Physics |
Deposited On: | 2009-01-28 |
Last Modified: | 2020-12-02 |
Downloads: | 0 |
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