QUASARS: INDIVIDUAL: HE 1104-1805; TECHNIQUES: IMAGE PROCESSING; GRAVITATIONAL LENSING
Abstract :
[en] High angular resolution ground-based direct imaging (V, R, I_c) of the double QSO HE 1104-1805 has been obtained with the NOT and NTT telescopes. Analysis of these data led to the first detection of the lensing galaxy. Direct imaging of HE 1104-1805 has subsequently been carried out with the Planetary Camera (WFPC2) through the F555W (nearly Johnson V) and F814W (nearly Kron-Cousins I_c) filters onboard HST. These images confirm the presence of the deflector between the two lensed quasar components (A & B). Direct imaging of this system in the near infrared (IR) at 2.2 mu-m (K'), with IRAC-2b at the Cassegrain focus of the ESO/MPI 2.2 m telescope, indicates that the additional component is indeed a very red extended object with magnitude K ~= 16.5. We present deconvolutions of the HST and IR images using the 2-channel PLUCY method. From the HST observations, we also report very accurate relative positions and brightnesses of the QSO components. By comparison between the ground-based and the HST observations, from February-March 1994 to November 1995, we possibly detect the fading of component A by ~ 0.3 magnitudes in the optical and a corresponding fading of B by about half this value. The observed monotonic decrease of the magnitude difference between B and A as a function of wavelength is consistent with a partial amplification of the A component by microlensing. Evolutionary models for galaxies show that, in order to produce the observed colour indices V - I_c > 2 and 4 < I_c - K < 4.5, the galaxy is likely to be of elliptical type with a redshift 0.95 < z < 1.4. This range is consistent with the redshift z=1.32 measured from the absorption lines of metallic species in the spectra of the quasar components. However, other values for the redshift of the lens inside this range cannot be excluded. This galaxy would presently be among the most distant known gravitational lenses. Several theoretical models are found to fit the observations. The simplest one is a singular isothermal sphere (SIS) lens immersed in an external shear with gamma=0.123. The derived mass-to-light ratio (11 h_50 M_Sun/L_Sun) for the galaxy is large but does not imply an excess of dark matter with respect to other well known lensing galaxies.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Remy, M.; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Claeskens, Jean-François ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Surdej, Jean ; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Hjorth, J.; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Refsdal, S.; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Wucknitz, O.; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Sorensen, A. N.; A (Institut d'Astrophysique, Université de Liège, Avenue de Cointe 5, B-4000 Liège, Belgium) ; B (Nordic Institute foR Theoretical Physics, Blegdamsvej 17, DK-2100 CopenhageN Ø, Denmark) ; C (Hamburg Observatory, Gojenbergsweg 112, D-21029 Hamburg, Germany) ; D (Copenhagen University Observatory, Niels Bohr Institute for Astronomy, Physics and Geophysics, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark) ; E (Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC. V8X 4M6, Canada)
Grundahl, F.
Language :
English
Title :
Detection of the lensing galaxy for the double QSO HE 1104-1805