Hubble Frontier Field Free-Form Mass Mapping of the Massive Multiple-Merging Cluster MACSJ0717.5+3745

Understand

We examine the latest data on the cluster MACSJ0717.5+3745 from the Hubble Frontier Fields campaign.

• The critically lensed area is the largest known of any lens and very irregular making it a challenge for parametric modelling.
• Using our Free-Form method we obtain an accurate solution, identify here many new sets of multiple images, doubling the number of constraints and improving the reconstruction of the dark matter distribution.
• Our reconstructed mass map shows several distinct central substructures with shallow density profiles, clarifying earlier work and defining well the relation between the dark matter distribution and the luminous and X-ray peaks within the critically lensed region.