| Description |
For deep imaging longward of 100 um, confusion noise sets the
fundamental sensitivity limits achievable with Herschel, and these
limits cannot be improved by integrating longer. To penetrate through
this confusion limit and detect faint high-redshift galaxies,
gravitational lensing by massive galaxy clusters offers a very
powerful and yet cheap solution. For this reason, our team has been
conducting a PACS/SPIRE imaging survey of 44 massive lensing clusters
as one of the Herschel Key Programs, The Herschel Lensing Survey
(PI: Egami, 292.3 hrs). Deep PACS/SPIRE imaging data of massive
clusters are quite rich with a variety of information, which allows us
to study not only the properties of gravitationally lensed
high-redshift galaxies but also those of cluster member galaxies and
the intracluster medium through the analysis of the Sunyaev-Zeldovich
effect.
In January 2010, a massive HST program targeting powerful lensing
clusters was accepted as one of the three multi-cycle treasury (MCT)
programs. This program, ``the Cluster Lensing And Supernova survey
with Hubble (CLASH), has an allocation of 524 orbits, and will
obtain deep ACS and WFC3 images of 25 massive galaxy clusters using 16
broad-band filters from near-UV (2250 A) to near-IR (1.6 um). These
extensive multi-filter imaging observations will produce
high-precision photometric redshifts (sigma/(1+z)<0.02). On average,
the program spends 20 orbits per cluster. Considering this enormous
investment of HST time, the CLASH program will define the ultimate
sample of massive galaxy clusters on which future studies will focus.
Here, we propose to obtain deep PACS and SPIRE images for 10 CLASH
clusters that still lack such data (the other 15 clusters already have
a good Herschel coverage). To fully exploit the combination of the
Herschel and HST data, the HLS and CLASH teams are submitting this
proposal jointly with the participation of key scientists from both
teams. |
