The Cluster Lensing and Supernova Survey with Hubble: An Overview

Creators: Postman, Marc; Bouwens, Rychard

Abstract

The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit Multi-Cycle Treasury Program to use the gravitational lensing properties of 25 galaxy clusters to accurately constrain their mass distributions. The survey, described in detail in this paper, will definitively establish the degree of concentration of dark matter in the cluster cores, a key prediction of structure formation models. The CLASH cluster sample is larger and less biased than current samples of space-based imaging studies of clusters to similar depth, as we have minimized lensing-based selection that favors systems with overly dense cores. Specifically, 20 CLASH clusters are solely X-ray selected. The X-ray-selected clusters are massive (kT > 5 keV) and, in most cases, dynamically relaxed. Five additional clusters are included for their lensing strength (θ_Ein > 35" at z_s = 2) to optimize the likelihood of finding highly magnified high-z (z > 7) galaxies. A total of 16 broadband filters, spanning the near-UV to near-IR, are employed for each 20-orbit campaign on each cluster. These data are used to measure precise (σ_z ~ 0.02(1 + z)) photometric redshifts for newly discovered arcs. Observations of each cluster are spread over eight epochs to enable a search for Type Ia supernovae at z > 1 to improve constraints on the time dependence of the dark energy equation of state and the evolution of supernovae. We present newly re-derived X-ray luminosities, temperatures, and Fe abundances for the CLASH clusters as well as a representative source list for MACS1149.6+2223 (z = 0.544).

Additional Information

© 2012 American Astronomical Society. Received 2011 June 16, accepted for publication 2011 December 5; Published 2012 March 14. We are especially grateful to our program coordinator Beth Perrillo for her expert assistance in implementing the HST observations in this program. We thank Jay Anderson and Norman Grogin for providing the ACS CTE and bias-striping correction algorithms used in our data pipeline. Finally, we are indebted to the hundreds of people who have labored many years to plan, develop, manufacture, install, repair, and calibrate the WFC3 and ACS instruments as well as to all those who maintain and operate the Hubble Space Telescope. The CLASH Multi-Cycle Treasury Program (GO-12065) is based on observations made with the NASA/ESA Hubble Space Telescope. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. ACS was developed under NASA contract NAS 5-32864. This research is supported in part by NASA grant HST-GO-12065.01-A, the Israel Science Foundation, the Baden-Wuerttemberg Foundation, the German Science Foundation (Transregio TR 33), Spanish MICINN grant AYA2010-22111-C03-00, funding from the Junta de Andaluca Proyecto de Excelencia NBL2003, INAF contracts ASI-INAF I/009/10/0, ASI-INAF I/023/05/0, ASI-INAF I/088/06/0, PRIN INAF 2009, and PRIN INAF 2010, NSF CAREER grant AST-0847157, the UK's STFC, the Royal Society, the Wolfson Foundation, and National Science Council of Taiwan grant NSC97-2112-M-001-020-MY3. A.Z. acknowledges support by the John Bahcall excellence prize. L.I. acknowledges support from a Conicyt FONDAP/BASAL grant. P.R. and S.S. acknowledge support from the DFG cluster of excellence Origin and Structure of the Universe program.

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