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Scintillation is an indicator of astrometric stability
Schaap, RG and Shabala, SS and Ellingsen, SP and Titov, OA and Lovell, JEJ, Scintillation is an indicator of astrometric stability, Monthly Notices of the Royal Astronomical Society, 434, (1) pp. 585-594. ISSN 0035-8711 (2013) [Refereed Article]
Copyright 2013 The Authors
We examine the relationship between astrometric stability and astrophysical properties in flat-spectrum radio-loud quasars making up the celestial reference frame. We use position determinations from geodetic very long baseline interferometry measurements and develop a new metric for source position stability. We then compare this quantity to two measures of source compactness: structure index, which probes structure on milliarcsecond scales and the presence of interstellar scintillation associated with the quasar, which probes scales of tens of μas.
We find that persistent scintillators have greater position stability than episodic scintillators, which are in turn more stable than non-scintillators. Scintillators are also more likely to be compact on milliarcsecond scales, as measured by the structure index. Persistent scintillators are therefore excellent candidates for inclusion in any future realization of the celestial reference frame. A list of these sources is presented in Appendix A.
We find that slow (characteristic time-scale >3 d) scintillators have more stable positions than rapid scintillators, suggesting that they are more compact. High-cadence, long-term monitoring is therefore required to identify other members of this population of compact, high brightness temperature quasars.
|Item Type:||Refereed Article|
|Keywords:||scattering – astrometry – reference systems – ISM: structure – 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:||Schaap, RG (Mr Robert Schaap)|
|UTAS Author:||Shabala, SS (Associate Professor Stas Shabala)|
|UTAS Author:||Ellingsen, SP (Professor Simon Ellingsen)|
|UTAS Author:||Lovell, JEJ (Dr Jim Lovell)|
|Web of Science® Times Cited:||6|
|Deposited By:||Mathematics and Physics|
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