The Mass Distribution of the Strong Lensing Cluster SDSS J1531+3414
  We present the mass distribution at the core of SDSS J1531+3414, a strong-lensing cluster at z=0.335. We find that the mass distribution is well described by two cluster-scale halos with a contribution from cluster-member galaxies. New HST observations of SDSS J1531+3414 reveal a signature of ongoing star formation associated with the two central galaxies at the core of the cluster, in the form of a chain of star forming regions at the center of the cluster. Using the lens model presented here, we place upper limits on the contribution of a possible lensed image to the flux at the center region, and rule out that this emission is coming from a background source. 
Keren Sharon, Michael D. Gladders, Jane R. Rigby, Eva Wuyts, Matthew   B. Bayliss, Traci L. Johnson, Michael K. Florian, and...
astro-ph.CO astro-ph.GA