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Magnification, dust and time-delay constraints from the first resolved strongly lensed Type Ia supernova iPTF16geu

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. (2020) Magnification, dust and time-delay constraints from the first resolved strongly lensed Type Ia supernova iPTF16geu. Monthly Notices of the Royal Astronomical Society, 491 (2). pp. 2639-2654. ISSN 0035-8711. doi:10.1093/mnras/stz2965.

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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. Multiband 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 d. Interestingly, we find large differences between the magnifications of the four supernova images, even after accounting for uncertainties in the extinction corrections: Δm₁ = −3.88^(+0.07)_(−0.06), Δm₂ = −2.99^(+0.09)_(−0.08)⁠, Δm₃ = −2.19^(+0.14)_(−0.15)⁠, and Δm₄ = −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:Article
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 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 ( Accepted 2019 October 20. Received 2019 October 20; in original form 2019 July 15. Published: 26 October 2019. 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 AgencyUNSPECIFIED
Swedish Research CouncilUNSPECIFIED
Subject Keywords:gravitational lensing: strong – supernovae: general – supernova: individual
Issue or Number:2
Record Number:CaltechAUTHORS:20200302-094930578
Persistent URL:
Official Citation:S Dhawan, J Johansson, A Goobar, R Amanullah, E Mörtsell, S B Cenko, A Cooray, O Fox, D Goldstein, R Kalender, M Kasliwal, S R Kulkarni, W H Lee, H Nayyeri, P Nugent, E Ofek, R Quimby, Magnification, dust, and time-delay constraints from the first resolved strongly lensed Type Ia supernova iPTF16geu, Monthly Notices of the Royal Astronomical Society, Volume 491, Issue 2, January 2020, Pages 2639–2654,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101647
Deposited By: Tony Diaz
Deposited On:02 Mar 2020 19:21
Last Modified:16 Nov 2021 18:04

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