Hubble Frontiers Fields : New Insights after 2 years of observations

The Hubble Frontier Fields (HFF) initiative constitutes the largest commitment ever of HST time to the exploration of the distant Universe via gravitational lensing by massive galaxy clusters. This program devotes 140 orbits of HST time to deep imaging observations of each of six cluster lenses reaching m~29 (AB) uniformly from the optical to the near-infrared.

After two years, four clusters have been fully observed, and the last two are on their way ! I will present our team's new gravitational lensing pictures of these four complex systems using this exquisite set of data. These clusters act as amazing Cosmic Telescopes, serving the HFF primary goal : the quest for the high-redshift Universe. But that's not all! This dataset allowed for incredible discoveries, one of the most beautiful one being SN Refsdal, a multiply-lensed supernovae discovered by Kelly et al. (2015) in MACSJ1149. This particular event is a rare chance to test our mass modeling techniques, and hopefully improve our methods.

I will thus give an overview of the lensing community's work on SN Refsdal, and discuss the appearance of its last multiple image.