Illuminating a dark lens: A type ia supernova magnified by the frontier fields galaxy cluster abell 2744

Steven A. Rodney, Brandon Patel, Daniel Scolnic, Ryan J. Foley, Alberto Molino, Gabriel Brammer, Mathilde Jauzac, Maruša Bradač, Tom Broadhurst, Dan Coe, Jose M. Diego, Or Graur, Jens Hjorth, Austin Hoag, Saurabh W. Jha, Traci L. Johnson, Patrick Kelly, Daniel Lam, Curtis McCully, Elinor MedezinskiMassimo Meneghetti, Julian Merten, Johan Richard, Adam Riess, Keren Sharon, Louis Gregory Strolger, Tommaso Treu, Xin Wang, Liliya L R Williams, Adi Zitrin

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


SN HFF14Tom is a Type Ia SN discovered at Z = 1.3457 ± 0.0001 behind the galaxy cluster Abell 2744 (Z = 0.308). In a cosmology-independent analysis, we find that HFF14Tom is 0.77 ± 0.15 mag brighter than unlensed Type Ia SNe at similar redshift, implying a lensing magnification of μobs = 2.03 ± 0.29. This observed magnification provides a rare opportunity for a direct empirical test of galaxy cluster lens models. Here we test 17 lens models, 13 of which were generated before the SN magnification was known, qualifying as pure "blind tests. " The models are collectively fairly accurate: 8 of the models deliver median magnifications that are consistent with the measured μ to within 1λ. However, there is a subtle systematic bias: the significant disagreements all involve models overpredicting the magnification. We evaluate possible causes for this mild bias, and find no single physical or methodological explanation to account for it. We do find that model accuracy can be improved to some extent with stringent quality cuts on multiply imaged systems, such as requiring that a large fraction have spectroscopic redshifts. In addition to testing model accuracies as we have done here, Type Ia SN magnifications could also be used as inputs for future lens models of Abell 2744 and other clusters, providing valuable constraints in regions where traditional strong- and weak-lensing information is unavailable.

Original languageEnglish (US)
Article number70
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 20 2015

Bibliographical note

Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved.


  • galaxies: clusters: general
  • galaxies: clusters: individual (Abell 2744)
  • gravitational lensing: strong
  • gravitational lensing: weak
  • supernovae: general
  • supernovae: individual (HFF14Tom)


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