GALAXY-SCALE STRONG-LENSING TESTS OF GRAVITY AND GEOMETRIC COSMOLOGY: CONSTRAINTS AND SYSTEMATIC LIMITATIONS
Author(s)Schwab, Josiah; Bolton, Adam S.; Rappaport, Saul A.
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Galaxy-scale strong gravitational lenses with measured stellar velocity dispersions allow a test of the weak-field metric on kiloparsec scales and a geometric measurement of the cosmological distance-redshift relation, provided that the mass-dynamical structure of the lensing galaxies can be independently constrained to a sufficient degree. We combine data on 53 galaxy-scale strong lenses from the Sloan Lens ACS Survey with a well-motivated fiducial set of lens-galaxy parameters to find (1) a constraint on the post-Newtonian parameter γ = 1.01 ± 0.05, and (2) a determination of ΩΛ = 0.75 ± 0.17 under the assumption of a flat universe. These constraints assume that the underlying observations and priors are free of systematic error. We evaluate the sensitivity of these results to systematic uncertainties in (1) total mass-profile shape, (2) velocity anisotropy, (3) light-profile shape, and (4) stellar velocity dispersion. Based on these sensitivities, we conclude that while such strong-lens samples can, in principle, provide an important tool for testing general relativity and cosmology, they are unlikely to yield precision measurements of γ and Ω[subscript Λ] unless the properties of the lensing galaxies are independently constrained with substantially greater accuracy than at present.
DepartmentKavli Institute for Astrophysics and Space Research; Massachusetts Institute of Technology. Department of Physics
American Astronomical Society
Rappaport, Saul A., Adam S. Bolton, and Josiah Schwab. “GALAXY-SCALE STRONG-LENSING TESTS OF GRAVITY AND GEOMETRIC COSMOLOGY: CONSTRAINTS AND SYSTEMATIC LIMITATIONS*.” The Astrophysical Journal 708.1: 750-757. © 2010 The American Astronomical Society
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