1. CLASH: Cluster Lensing And Supernova survey with Hubble ACS Parallels WFC3 Parallels 6 arcmin. = 2.2 Mpc @ z=0.5 Footprints of HST Cameras: ACS FOV in yellow, WFC3/IR FOV in red, WFC3/UVIS in blue. Cluster Pointings SN search cadence: 10d-20d, 4 epochs per orient Lensing amplification small at these radii 524 orbits, 25 clusters, 16 filters, ~3 years M. Postman, P.I., with 34 co-investigators (18 institutions, 10 countries)

2. Abell 209Abell 383 coreAbell 611Abell 963Abell 2261CLJ1226+3332 MACS 0329-0211 MACS 0717+3745 MACS 0744+3927MACS 1115+0129 MACS 1149+2223 MACS 1206-0847 RXJ 0647+7015 Cutouts of x-ray images of 23 of the 25 CLASH clusters from Chandra Observatory RXJ 1347-1145RXJ 1423+2404 MS-2137 core RXJ 1720+3536RXJ 2129+0005 MACS 0429-0253 MACS 1311-0310 RXJ 1532+3020MACS 1931-2634RXJ 2248-4431 All clusters have T x > 5 keV z_med ~ 0.4

3. CLASH: 16 Passbands per cluster from UV to NIR Mag distn of multiply lensed arcs in A1689 and CL0024 Will yield photometric redshifts with rms error of ~2% x (1 + z) for sources down to ~26 AB mag. Spectroscopic redshifts Photometric redshifts Why 16 filters? Arcs in A1689 and CL0024 F225W … 235.9 nm WFC3/UVIS F275W … 270.4 nm WFC3/UVIS F336W … 335.5 nm WFC3/UVIS F390W … 392.1 nm WFC3/UVIS F435W … 430.6 nm ACS/WFC F475W … 474.2 nm ACS/WFC F606W … 592.0 nm ACS/WFC F625W … 629.8 nm ACS/WFC F775W … 769.4 nm ACS/WFC F814W … 806.9 nm ACS/WFC F850LP … 906.0 nm ACS/WFC F105W … 1.055 μm WFC3/IR F110W … 1.152 μm WFC3/IR F125W … 1.248 μm WFC3/IR F140W … 1.392 μm WFC3/IR F160W … 1.536 μm WFC3/IR F225W … 235.9 nm WFC3/UVIS F275W … 270.4 nm WFC3/UVIS F336W … 335.5 nm WFC3/UVIS F390W … 392.1 nm WFC3/UVIS F435W … 430.6 nm ACS/WFC F475W … 474.2 nm ACS/WFC F606W … 592.0 nm ACS/WFC F625W … 629.8 nm ACS/WFC F775W … 769.4 nm ACS/WFC F814W … 806.9 nm ACS/WFC F850LP … 906.0 nm ACS/WFC F105W … 1.055 μm WFC3/IR F110W … 1.152 μm WFC3/IR F125W … 1.248 μm WFC3/IR F140W … 1.392 μm WFC3/IR F160W … 1.536 μm WFC3/IR

4. What is the characteristic distribution of DM in a typical cluster, and what implications does this distribution have for structure formation and the nature of DM? CLASH will: Use 3 independent lensing constraints: SL, WL, mag bias Have a well-selected cluster sample with minimal lensing bias Definitively derive the representative equilibrium mass profile shape Robustly measure cluster DM concentrations and their dispersion as a function of cluster mass (and possibly their redshift evolution). Provide excellent calibration of mass-observable relations for clusters ΛCDM Theory LCDM prediction from Duffy et al. 2008Umetsu et al. 2010

5. Abell 1689 Coe et al. 2010 What degree of substructure exists in the DM distribution in cluster cores? HST Image of Cluster Reconstructed Mass Surface Density Region of Reliable Reconstruction DM substructure resolution in this map is ~23 kpc. DM substructure resolution for typical CLASH cluster will be ~30 – 40 kpc.

6. First CLASH Cluster: Abell 383

7. Does the Equation of State of Dark Energy Depend on Time? Reference Discovery Difference Nov 18, 2010 Dec 8, 2010 Dec 28, 2010 WFC3-IR, F160W, z ~ 0.7 or 1.7 ACS, F850LP, z ~ 0.3 Abell 383 SN Candidate “Caligula”Abell 383 SN Candidate “Nero” HST LIFETIME CURRENT MCT Δ mag (vs. w o = -1, w a = 0) Expect CLASH to find 10 – 20 SNe at z>1; and ~6 with z > 1.5, doubling the known number of z > 1 SNe. Two MCT HST programs (CLASH and CANDELS) will detect SNe Ia at 1.0 < z < 2.5. CLASH and CANDELS provide a direct test of the SN systematics in a matter- dominated universe. Expect CLASH to find 10 – 20 SNe at z>1; and ~6 with z > 1.5, doubling the known number of z > 1 SNe. Two MCT HST programs (CLASH and CANDELS) will detect SNe Ia at 1.0 < z < 2.5. CLASH and CANDELS provide a direct test of the SN systematics in a matter- dominated universe.

8. Lensing greatly enhances the ability to detect distant galaxies and provides an additional constraint on their redshifts, as the projected position of the lensed object is a function of the source redshift. What are the characteristics of the most distant galaxies in the universe? Bradley et al. 2010 (in prep): Abell 1703 – Brightest z ~ 7 candidate known (H160 ~ 24.3 AB), μ ~ 3 - 5 ■Reconstruction of a z = 4.92 source lensed by the z = 0.33 cluster MS1358+62. ■Best resolved high-z object: spatial resolution of ~50 pc (rest-frame UV) ■Equivalent to 20-m space telescope resolution of a non-lensed z=5 galaxy! ■Reconstruction of a z = 4.92 source lensed by the z = 0.33 cluster MS1358+62. ■Best resolved high-z object: spatial resolution of ~50 pc (rest-frame UV) ■Equivalent to 20-m space telescope resolution of a non-lensed z=5 galaxy! Zitrin et al. 2010 0.2” ACS PSF z = 4.92 Galaxy How object would look without cluster lensing

9. Concluding Comments CLASH observations with HST began in November. The 25 clusters will be observed over the course of cycles 18-20 (~3 years): 10, 10, 5. Represents a major observational initiative to constrain the properties of DM, high-z galaxies, and advance our understanding of DE. Immediate public access to all HST data. High-level science products will be released on a regular schedule, including compilations of x- ray, IR, sub-mm, and spectroscopic data. http://www.stsci.edu/~postman/CLASH CLASH observations with HST began in November. The 25 clusters will be observed over the course of cycles 18-20 (~3 years): 10, 10, 5. Represents a major observational initiative to constrain the properties of DM, high-z galaxies, and advance our understanding of DE. Immediate public access to all HST data. High-level science products will be released on a regular schedule, including compilations of x- ray, IR, sub-mm, and spectroscopic data. http://www.stsci.edu/~postman/CLASH

11. CLASH Yields a Significant Expansion of SL Cluster Data Strongly Lensing Clusters with 3 or more filters from HST (ACS and/or WFC3) Figure credit: Dan Coe CLASH doubles the number of SL clusters with >3 HST passbands. CLASH has uniform and well-defined sample selection criteria. Vast improvement in number of SLCs with >6 passbands – new territory for science.