CLASH: The enhanced lensing efficiency of the highly elongated merging cluster MACS J0416.1-2403

Understand

We perform a strong-lensing analysis of the merging galaxy cluster MACS J0416.1-2403 (M0416; z=0.42) in recent CLASH/HST observations.

• We identify 70 new multiple images and candidates of 23 background sources in the range 0.7<z_{phot}<6.14 including two probable high-redshift dropouts, revealing a highly elongated lens with axis ratio ~5:1, and a major axis of ~100\arcsec (z_{s}~2).
• Compared to other well-studied clusters, M0416 shows an enhanced lensing efficiency.
• Although the critical area is not particularly large (~0.6 \square\arcmin; z_{s}~2), the number of multiple images, per critical area, is anomalously high.