2000/01/28 by C. R. Keeton, E. E. Falco, E. Falco +10 · 72 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy #Astrophysics #Barred spiral galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Gamma-ray bursts and supernovae #Gravitational lens #Hubble's law #Interacting galaxy #Lens (geology) #Optics #Physics #Quasar #Redshift #astro-ph
paper · pdf · doi:10.1086/309517
published in The Astrophysical Journal 542(1), 74-93 (IOP Publishing) · Submitted to ApJ; 33 pages with 3 embedded figures, plus 6 GIF figures; full paper with all figures embedded available at http://cfa-www.harvard.edu/glensdata/papers.html
arxiv created 2000/01/28 · openalex publication_date 2000/10/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Infrared images of the Q0957+561 gravitational lens obtained with the Hubble Space Telescope show two large (~5'') lensed images of the z s = 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 H 0 . 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.