Ricardo Perez Martinez
XMM/Newton 

After getting a degree in physics/astrophysics at Universidad
Complutense de Madrid, I joined the ARCS consortium at VILSPA/ESAC
in 2001 to do a PhD under the supervision of Leo Metcalfe. The ARCS
consortium was and still is a collaboration of several institution
to acquire and exploit observational data of galaxy clusters with
significant gravitational lensing effects. Nowadays, the group is
formed at ESAC by Leo Metcalfe, Bruno Altieri, Daniela Coia, Celia
Sanchez and myself.

The gravitational lensing effect has been used as a natural
telescope to resolve faint infrared sources with ISOCAM (7 and 15
microns), getting sensitivities up to three times deeper than those
from ISO field surveys and resolving a significant part of the
cosmic infrared background. The most of the sources identified had
characteristics compatible with highly obscured star formation
activity in the range of z=0.5-1.5

We are now focusing in the characterization of the cluster members,
using IR data (7 and 15 microns from ISO and now 3.6, 4.5, 5.8, 8.0
and 24 microns from Spitzer) together with optical and x-ray. First
results indicate a higher stellar formation activity than
previously estimated, basically due to heavy dust obscuration. 

In the future we plan to expand the exploitation of Spitzer data as
well as to carry out new observations with satellite borne and
ground based telescopes.