Bibcode
DOI
Keeton, C. R.; Falco, E. E.; Impey, C. D.; Kochanek, C. S.; Lehár, J.; McLeod, B. A.; Rix, H.-W.; Muñoz, J. A.; Peng, C. Y.
Bibliographical reference
The Astrophysical Journal, Volume 542, Issue 1, pp. 74-93.
Advertised on:
10
2000
Journal
Citations
68
Refereed citations
57
Description
Infrared images of the Q0957+561 gravitational lens obtained with the
Hubble Space Telescope show two large (~5") lensed images of the
zs=1.41 quasar host galaxy. Parts of the host galaxy are
doubly imaged, like the quasar, while other parts are quadruply imaged.
The distortions of the host galaxy offer the best probe yet of the
global structure of the lensing potential, which is essential for
determining the Hubble constant from the measured time delay. The
distortions are inconsistent with the predictions of previously
published lens models, which invalidates those models and their
implications for H0. New models show that the distortions
finally break the long-standing degeneracy between the shape of the lens
galaxy and the tidal shear contributed by the cluster containing the
lens galaxy. The shape of the lens galaxy's mass distribution must be
remarkably similar to the shape of its luminosity distribution, and most
models that produce reasonable values for the Hubble constant roughly
match the observed ellipticity gradient and isophote twist of the lens
galaxy. In addition, the cluster must be nonspherical and produce a
relatively small tidal shear. Although there are still degeneracies in
the lens models that lead to a 25% uncertainty in the derived value of
the Hubble constant, there are also strong prospects for new
observations to further improve the constraints and reduce the
uncertainties. Based on observations made with the NASA/ESA Hubble Space
Telescope, obtained at the Space Telescope Science Institute, which is
operated by AURA, Inc., under NASA contract NAS 5-26555.