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The impact of microlensing on the standardisation of strongly lensed Type Ia supernovae

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We investigate the effect of microlensing on the standardisation of strongly lensed Type Ia supernovae (GLSNe Ia). We present predictions for the amount of scatter induced by microlensing across a range of plausible strong lens macromodels. We find that lensed images in regions of low convergence, shear and stellar density are standardisable, where the microlensing scatter is comparable to the intrinsic dispersion of a typical SN Ia. These standardiable configurations correspond to the outer image of an asymmetric double for lenses with large Einstein radii. Quadruple image systems, symmetric doubles and small Einstein radii lenses are not standardisable. We apply our model to the recently discovered GLSN Ia iPTF16geu and find that the large discrepancy between the observed flux and the macromodel predictions from More et al. 2016 cannot be explained by microlensing alone. Using the mock GLSNe Ia catalogue of Goldstein et al. 2017, we predict that ~22% of GLSNe Ia discovered by LSST will be standardisable, with a median Einstein radius of 0.9 arcseconds and a median time-delay of 41 days. By breaking the mass-sheet degeneracy the full LSST GLSNe Ia sample will be able to detect systematics in H0 at the 0.5% level.
Original languageEnglish
Pages (from-to)5081-5090
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume478
Issue number4
Early online date22 May 2018
DOIs
Publication statusPublished - 21 Aug 2018

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    Rights statement: This article has been accepted for publication in MNRAS ©: 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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