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A radio-microlensing caustic crossing in B1600+434?

L. V. E. Koopmans·A. G. de Bruyn·J. Wambsganss·C. D. Fassnacht
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Abstract

First, we review the current status of the detection of strong `external' variability in the CLASS gravitational B1600+434, focusing on the 1998 VLA 8.5-GHz and 1998/9 WSRT multi-frequency observations. We show that this data can best be explained in terms of radio-microlensing. We then proceed to show some preliminary results from our new multi-frequency VLA monitoring program, in particular the detection of a strong feature (~30%) in the light curve of the lensed image which passes predominantly through the dark-matter halo of the lens galaxy. We tentatively interpret this event, which lasted for several weeks, as a radio-microlensing caustic crossing, i.e. the superluminal motion of a micro-arcsec-scale jet-component in the lensed source over a single caustic in the magnification pattern, that has been created by massive compact objects along the line-of-sight to the lensed image.

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L. V. E. Koopmans, A. G. de Bruyn, J. Wambsganss, C. D. Fassnacht. 2000-04-19. A radio-microlensing caustic crossing in B1600+434?. https://arxiv.org/abs/astro-ph/0004285

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