The Possible Origins of the VR Magnification Ratios of Q0957+561AB

Bibcode
2005IAUS..225..305U
DOI
10.1017/S1743921305002103
Ullán, A.; Goicoechea, L. J.; Gil-Merino, R.; Serra-Ricart, M.; Muñoz, J. A.; Mediavilla, E.; González-Cadelo, J.; Oscoz, A.
Bibliographical reference

Gravitational Lensing Impact on Cosmology, IAU Symposium, vol. 225. Edited by Yannick Mellier and Georges Meylan, ISBN 0521851963. Cambridge, UK: Cambridge University Press, 2005., p.305-310

Advertised on:
6
2005
Number of authors
8
IAC number of authors
0
Citations
2
Refereed citations
2
Description
We present VR magnification ratios of the double quasar Q0957+561AB, which are inferred from frames taken with the 2.56m Nordic Optical Telescope. From two different photometric techniques (pho2comC and psfphot) and a reasonable range for the time delay in the system (415-430 days), we find optical continuum ratios depending on the wavelength. These chromatic ratios are consistent with either differential extinction in a dust system or gravitational microlensing in the deflector. Although the dusty scenario is only viable for a compact dust cloud in the line of sight to the A component, the possible values for the differential extinction and the ratio of total to selective extinction in the V band are surprisingly reasonable. To decide on the true origin of the anomalous ratios (extinction, microlensing or a mixed scenario), we are carrying out new monitoring campaigns and planning detailed observations from the best ground-based and space telescopes.
Type
Non-refereed

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