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

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Title: Galaxy mass profiles from strong lensing II: The elliptical power-law model
Authors: O’Riordan, CM
Warren, SJ
Mortlock, DJ
Item Type: Journal Article
Abstract: We present a systematic analysis of the constraints σγ on the mass profile slope γ 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 σγ for two image systems are well described by the results of Paper I, transformed to elliptical coordinates; 2. We derive an analytical expression for σγ for systems with the source aligned with the axis of the lens; 3. For both two-image systems and aligned systems, σγ 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 γ 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 σγ < 0.01, for S = 100, occur when the source approaches the caustic.
Issue Date: Aug-2020
Date of Acceptance: 11-Jun-2020
URI: http://hdl.handle.net/10044/1/80487
DOI: 10.1093/mnras/staa1697
ISSN: 0035-8711
Publisher: Oxford University Press (OUP)
Start Page: 3424
End Page: 3435
Journal / Book Title: Monthly Notices of the Royal Astronomical Society
Volume: 496
Issue: 3
Copyright Statement: © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). This is a pre-copy-editing, author-produced version of an article accepted for publication in the Royal Astronomical Society following peer review. The definitive publisher-authenticated version C M O’Riordan, S J Warren, D J Mortlock, Galaxy mass profiles from strong lensing II: The elliptical power-law model, Monthly Notices of the Royal Astronomical Society, , staa1697, https://doi.org/10.1093/mnras/staa1697
Keywords: astro-ph.GA
astro-ph.GA
Astronomy & Astrophysics
0201 Astronomical and Space Sciences
Publication Status: Published online
Online Publication Date: 2020-06-16
Appears in Collections:Physics
Astrophysics