Galaxy mass profiles from strong lensing II: The elliptical power-law model

Abstract

We present a systematic analysis of the constraints ${\sigma }_{\gamma }$ on the mass profile slope $\gamma$ obtainable when fitting a singular power-law ellipsoid model to a typical strong lensing observation of an extended source. These results extend our previous analysis of circular systems, Paper I. We draw our results from 676 mock observations covering a range of image configurations, each created with a fixed signal to noise ratio $S=100$ in the images. We analyse the results using a combination of theory and a simplified model which identifies the contribution to the constraints of the individual fluxes and positions in each of the lensed images. The main results are: 1. For any lens ellipticity, the constraints ${\sigma }_{\gamma }$ for two image systems are well described by the results of Paper I, transformed to elliptical coordinates; 2. We derive an analytical expression for ${\sigma }_{\gamma }$ for systems with the source aligned with the axis of the lens; 3. For both two-image systems and aligned systems, ${\sigma }_{\gamma }$ is limited by the flux uncertainties; 4. The constraints for off-axis four-image systems are a factor of two to eight better, depending on source size, than for two-image systems, and improve with increasing lens ellipticity. We show that the constraints on $\gamma$ in these systems derive from the complementary positional information of the images alone, without using flux. The complementarity improves as the offset of the source from the axis increases, such that the best constraints ${\sigma }_{\gamma }<0.01$, for $S=100$, occur when the source approaches the caustic.

arXiv comment12 pages, 9 figures. Accepted for publication in MNRAS

References in corpus (18)

• The Sloan Lens ACS Survey. V. The Full ACS Strong-Lens Sample
• Dissecting the Gravitational Lens B1608+656. II. Precision Measurements of the Hubble Constant, Spatial Curvature, and the Dark Energy Equation of State
• The Structure & Dynamics of Massive Early-type Galaxies: On Homology, Isothermality and Isotropy inside one Effective Radius
• Dark Matter Contraction and the Stellar Content of Massive Early-type Galaxies: Disfavoring "Light" Initial Mass Functions
• Inference of the Cold Dark Matter substructure mass function at z=0.2 using strong gravitational lenses
• Fast calculation of a family of elliptical mass gravitational lens models
• Two-dimensional kinematics of SLACS lenses: II. Combined lensing and dynamics analysis of early-type galaxies at z = 0.08 - 0.33
• The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the BELLS GALLERY Sample
• Quantifying Environmental and Line-of-Sight Effects in Models of Strong Gravitational Lens Systems
• The elliptical power law profile lens
• A Unifying Framework for Self-consistent Gravitational Lensing and Stellar Dynamics Analyses of Early-Type Galaxies
• On the Choice of Lens Density Profile in Time Delay Cosmography
• A model-independent characterisation of strong gravitational lensing by observables
• Generalised model-independent characterisation of strong gravitational lenses II: Transformation matrix between multiple images
• Generalised model-independent characterisation of strong gravitational lenses I: Theoretical foundations
• Model-independent characterisation of strong gravitational lenses
• Observable properties of strong gravitational lenses
• Galaxy mass profiles from strong lensing I: The circular power-law model

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