Exploring effects on magnifications due to line-of-sight galaxies in the Hubble Frontier Fields

Catie A. Raney, Charles R. Keeton, Sean Brennan

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Cluster lensing has become an important tool in the search for high-redshift galaxies through its ability to magnify sources. In order to determine the intrinsic properties of these galaxies, lensing mass models must be constructed to determine the magnification of the images. These models are traditionally 2D, focusing on the mass within the cluster and either ignoring or approximating any contribution from line-of-sight galaxies. In this paper, we present the first full set of 3D mass models of the six Hubble Frontier Fields and use them to test for systematic biases in magnifications due to using the traditional 2D approach. We find that omitting foreground or background galaxies causes image position offsets between 0.1 and 0.4 arcsec, a non-negligible fraction of the typical 0.3-0.7 arcsec residuals of current state-ofthe- art models. We also find that median image magnifications can shift by up to 6 per cent, though it is dependent on the field. This can be alleviated in some cases by approximating the mass in the lensing plane, but a 5 per cent magnification bias still exists in other cases; image position offsets are also improved, but are still present at 0.10 arcsec.

Original languageEnglish (US)
Pages (from-to)503-527
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Feb 1 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies: clusters: general
  • Galaxies: clusters: individual: Abell 2744,MACS J0416.1+2403,MACS J1149.5+2223,MACS J0717.5+3745, Abell S1063, Abell 370
  • Galaxies: high-redshift
  • gravitational lensing: strong


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