Godzilla, a monster lurks in the Sunburst galaxy

Understand

We model the strong lensing effect in the galaxy cluster PSZ1 G311.65-18.48 (z=0.443) with an improved version of the hybrid method WSLAP+.

• We extend the number of constraints by including the position of critical points, which are combined with the classic positional constraints of the lensed galaxies.
• We pay special attention to a transient candidate source (Tr) previously discovered in the giant Sunburst arc (z=2.37).
• Our lens model predicts Tr to be within a fraction of an arcsecond from the critical curve, having a larger magnification factor than previously found, but still not large enough to explain the observed flux and lack of counterimages.