Article (Scientific journals)
A sharp look at the gravitationally lensed quasar SDSS J0806+2006 with laser guide star adaptive optics at the VLT
Sluse, Dominique; Courbin, F.; Eigenbrod, A. et al.
2008In Astronomy and Astrophysics, 492, p. 39-L42
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Keywords :
gravitational lensing; instrumentation: adaptive optics; techniques: high angular resolution
Abstract :
[en] We present the first VLT near-IR observations of a gravitationally lensed quasar, using adaptive optics and laser guide star. These observations can be considered as a test bench for future systematic observations of lensed quasars with adaptive optics, even when bright natural guide stars are not available in the nearby field. With only 14 min of observing time, we derived very accurate astrometry of the quasar images and of the lensing galaxy, with 0.05´´ spatial resolution, comparable to the Hubble Space Telescope (HST). In combination with deep VLT optical spectra of the quasar images, we use our adaptive optics images to constrain simple models for the mass distribution of the lensing galaxy. The latter is almost circular and does not need any strong external shear to fit the data. The time delay predicted for SDSS J0806+2006, assuming a singular isothermal ellipsoid model and the concordance cosmology, is Δ t ≃ 50 days. Our optical spectra indicate a flux ratio between the quasar images of A/B = 1.3 in the continuum and A/B = 2.2 in both the Mg ii and in the C iii] broad emission lines. This suggests that microlensing affects the continuum emission. However, the constant ratio between the two emission lines indicates that the broad emission line region is not microlensed. Finally, we see no evidence of reddening by dust in the lensing galaxy. Based on observations collected at the European Southern Observatory, Paranal, Chile, ESO Program 079.A-0588(A).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Sluse, Dominique  ;  Ecole Polytechnique Fédérale de Lausanne - EPFL > LASTRO
Courbin, F.;  Laboratoire d'astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
Eigenbrod, A.;  Laboratoire d'astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
Meylan, G.;  Laboratoire d'astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland)
Language :
English
Title :
A sharp look at the gravitationally lensed quasar SDSS J0806+2006 with laser guide star adaptive optics at the VLT
Publication date :
01 December 2008
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
492
Pages :
L39-L42
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
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