Intrinsic Degeneracy of Gravitational Lens Time Delays: the case for a simple quadruple system in $\Lambda$CDM cosmology

Abstract

A degeneracy in strong lens model is shown analytically. The observed time delays and quasar image positions might {\it not} uniquely determine the concentration and the extent of the lens galaxy halo mass distribution. Simply hardwiring the Hubble constant ($H_0$) and the cosmology ($\Omega ,\Lambda$) to the standard values of $\Lambda$CDM cosmology might {\it not} fully lift this degeneracy, which exists rigourously even with very accurate data. Equally good fits to the images could be found in lens mass models with either a mostly Keplerian or a flat rotation curve. This degeneracy in mass models makes the task of getting reliable $H_0$ and $\Lambda$ from strong lenses even more daunting.

5pp w/ 3 color eps fig (To be published in ApJ 582, 1/1/2003 Issue)

References in corpus (3)

• Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant
• What Do Gravitational Lens Time Delays Measure?
• Beware the Non-uniqueness of Einstein Rings

Cited by in corpus (10)

• Gravitational Lens Time Delays: A Statistical Assessment of Lens Model Dependences and Implications for the Global Hubble Constant
• Gravitational lens time delays for distant supernovae: break the degeneracy between radial mass profiles and the Hubble constant
• Gravitational lensing model degeneracies: Is steepness all-important?
• Gravitational Lens Time Delays in CDM
• Radial density profiles of time-delay lensing galaxies
• Two strong-lensing clusters confront universal dark-matter profiles
• Near-IR search for lensed supernovae behind galaxy clusters: III. Implications for cluster modeling and cosmology
• Lensing time delays as a substructure constraint: a case study with the cluster SDSS~J1004+4112
• Separating inner and outer contributions in gravitational lenses using the perturbative method
• The kinematical structure of gravitationally lensed arcs