Candidate strongly lensed type Ia supernovae in the Zwicky Transient Facility archive

Copyright and License

© The Authors 2025.

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work has been supported by the research project grant “Understanding the Dynamic Universe” funded by the Knut and Alice Wallenberg Foundation under Dnr KAW 2018.0067, Vetenskapsrådet, the Swedish Research Council, project 2020-03444, and the G.R.E.A.T research environment, project number 2016-06012. This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Office of High-Energy Physics, under Contract No. DE–AC02–05CH11231, and by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract. Additional support for DESI was provided by the U.S. National Science Foundation (NSF), Division of Astronomical Sciences under Contract No. AST-0950945 to the NSF’s National Optical-Infrared Astronomy Research Laboratory; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology of Mexico (CONACYT); the Ministry of Science and Innovation of Spain (MICINN), and by the DESI Member Institutions: https://www.desi.lbl.gov/collaborating-institutions. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U. S. National Science Foundation, the U. S. Department of Energy, or any of the listed funding agencies. The authors are honored to be permitted to conduct scientific research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation. S. Schulze is partially supported by LBNL Subcontract NO. 7707915. M. W. Coughlin acknowledges support from the National Science Foundation with grant numbers PHY-2308862 and PHY-2117997.

Data Availability

Table A.2 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/694/A146. All ZTF light curve data is publicly available at https://www.ztf.caltech.edu/ztf-public-releases.html. The instructions for how to install and run the AMPEL platform can be found at https://github.com/AmpelAstro/Ampel-HU-astro/. The specific AMPEL workflow we used to obtain the alert photometry, cross-match to galaxy catalogues, and perform initial filtering is found at https://github.com/AmpelAstro/Ampel-HU-astro/blob/main/notebooks/run_lensing_query.ipynb. The forced photometry pipeline for ZTF data that we utilised can be found at https://github.com/simeonreusch/fpbot. The BTS sample, which we utilised to estimate the contaminants present in our sample, is publicly accessible at https://sites.astro.caltech.edu/ztf/bts/explorer.php. All external data sources are referenced in the main text. Supplemental data are accessible at https://zenodo.org/records/11105340.