Abell 370 revisited: refurbished Hubble imaging of the first strong lensing cluster

Understand

We present a strong lensing analysis of the galaxy cluster Abell 370 (z=0.375) based on the recent multicolor ACS images obtained as part of the Early Release Observation (ERO) that followed the Hubble Service Mission #4.

• Back in 1987, the giant gravitational arc (z=0.725) in Abell 370 was one of the first pieces of evidence that massive clusters are dense enough to act as strong gravitational lenses.
• The new observations reveal in detail its disklike morphology, and we show that it can be interpreted as a complex five-image configuration, with a total magnification factor of 32+/-4.
• Moreover, the high resolution multicolor information allowed us to identify 10 multiply imaged background galaxies.