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Magnification, dust and time-delay constraints from the first resolved strongly lensed Type Ia supernova

Dhawan, S. and Johansson, J. and Goobar, A. and Amanullah, R. and Mörtsell, E. and Cenko, S. B. and Cooray, A. and Fox, O. and Goldstein, D. and Kalender, R. and Kasliwal, M. and Kulkarni, S. R. and Lee, W. H. and Nayyeri, H. and Nugent, P. and Ofek, E. and Quimby, R. (2019) Magnification, dust and time-delay constraints from the first resolved strongly lensed Type Ia supernova. . (Unpublished)

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We report lensing magnifications, extinction, and time-delay estimates for the first resolved, multiply-imaged Type Ia supernova iPTF16geu, at z = 0.409, using Hubble Space Telescope (HST) observations in combination with supporting ground-based data. Multi-band photometry of the resolved images provides unique information about the differential dimming due to dust in the lensing galaxy. Using HST and Keck AO reference images taken after the SN faded, we obtain a total lensing magnification for iPTF16geu of μ = 67.8^(+2.6)_(−2.9), accounting for extinction in the host and lensing galaxy. As expected from the symmetry of the system, we measure very short time-delays for the three fainter images with respect to the brightest one: -0.23 ± 0.99, -1.43 ± 0.74 and 1.36 ± 1.07 days. Interestingly, we find large differences between the magnifications of the four supernova images, even after accounting for uncertainties in the extinction corrections: Δm_1 = −3.88^(+0.07)_(−0.06), Δm_2 = −2.99^(+0.09)_(−0.08), Δm_3 = −2.19^(+0.14)_(−0.15) and Δm_4 = −2.40^(+0.14)_(−0.12) mag, discrepant with model predictions suggesting similar image brightnesses. A possible explanation for the large differences is gravitational lensing by substructures, micro- or millilensing, in addition to the large scale lens causing the image separations. We find that the inferred magnification is insensitive to the assumptions about the dust properties in the host and lens galaxy.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Johansson, J.0000-0001-5975-290X
Goobar, A.0000-0002-4163-4996
Amanullah, R.0000-0002-5559-9351
Cenko, S. B.0000-0003-1673-970X
Cooray, A.0000-0002-3892-0190
Fox, O.0000-0003-2238-1572
Goldstein, D.0000-0003-3461-8661
Kasliwal, M.0000-0002-5619-4938
Kulkarni, S. R.0000-0001-5390-8563
Nayyeri, H.0000-0001-8242-9983
Nugent, P.0000-0002-3389-0586
Ofek, E.0000-0002-6786-8774
Quimby, R.0000-0001-9171-5236
Additional Information:© 2019 The Authors. We would like to thank Justin Pierel for interesting discussions on the time-delay computation. AG acknowledges support from the Swedish National Space Agency and the Swedish Research Council.
Group:Astronomy Department
Funding AgencyGrant Number
Swedish National Space Board (SNSB)UNSPECIFIED
Swedish Research CouncilUNSPECIFIED
Subject Keywords:gravitational lensing: strong - Supernovae: general - Supernova: individual
Record Number:CaltechAUTHORS:20190722-114339649
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97325
Deposited By: Tony Diaz
Deposited On:22 Jul 2019 20:43
Last Modified:03 Oct 2019 21:30

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