Sub-milliarcsec-scale structure of the gravitational lens B1600+434

Abstract

In the gravitational lens system B1600+434 the brighter image, A, is known to show rapid variability which is not detected in the weaker image, B (Koopmans & de Bruyn 2000). Since correlated variability is one of the fundamental properties of gravitational lensing, it has been proposed that image A is microlensed by stars in the halo of the lensing galaxy (Koopmans & de Bruyn 2000). We present VLBA observations of B1600+434 at 15 GHz with a resolution of 0.5 milliarcsec to determine the source structure at high spatial resolution. The surface brightness of the images are significantly different, with image A being more compact. This is in apparent contradiction with the required property of gravitational lensing that surface brightness be preserved. Our results suggest that both the lensed images may show two-sided elongation at this resolution, a morphology which does not necessarily favour superluminal motion. Instead these data may suggest that image B is scatter-broadened at the lens so that its size is larger than that of A, and hence scintillates less than image A.

4 pages, 2 figures, accepted in AA Letters

References in corpus (4)

• An optical time-delay estimate for the double gravitational lens system B1600+434
• Keck Spectroscopy of Three Gravitational Lens Systems Discovered in the JVAS and CLASS Surveys
• The edge-on spiral gravitational lens B1600+434
• Milliarcsec-scale polarisation observations of the gravitational lens B1422+231

Cited by in corpus (3)

• Optical-radio positional offsets for active galactic nuclei
• Golden gravitational lensing systems from the Sloan Lens ACS Survey. I. SDSS J1538+5817: one lens for two sources
• The time delay of CLASS B1600+434 from VLA multi-frequency and polarization monitoring