9033( 17) - 03/04/03 06:26 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9033 Version: 17 Check-in Date: 04-Mar-2003 06:25:24 1.Proposal Title: Measuring the mass distribution in the most distant, very X-ray luminous galaxy cluster known ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Harald Ebeling University of Hawaii CoI: Nick Kaiser University of Hawaii N CoI: Caleb Scharf Columbia University N CoI: Laurence Jones University of Birmingham N CoI: Eric Perlman University of Maryland N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain a mosaic of deep HST/WFPC2 images to conduct a weak lensing analysis of the mass distribution in the massive, distant galaxy cluster ClJ1226.9+3332, recently discovered by us. At z=0.888 this exceptional system is more X-ray luminous and more distant than both MS1054.4-0321 and ClJ0152.7-1357, the previous record holders, thus providing yet greater leverage for cosmological studies of cluster evolution. ClJ1226.9+3332 differs markedly from all other currently known distant clusters in that it exhibits little substructure and may even host a cooling flow, suggesting that it could be the first cluster to be discovered at high redshift that is virialized. We propose joint HST and Chandra observations to investigate the dynamical state of this extreme object. This project will 1) take advantage of HST's superb resolution at optical wavelengths to accurately map the mass distribution within 1.9 h^(-1) 50 Mpc via strong and weak gravitational lensing, and 2) use Chandra's unprecedented resolution in the X-ray waveband to obtain independent constraints on the gas and dark matter distribution in the cluster core, including the suspected cooling flow region. As a bonus, the proposed WFPC2 observations will allow us to test the results by van Dokkum et al. (1998, 1999) on the properties of cluster galaxies (specifically merger rate and morphologies) at z~0.8 from their HST study of MS1054.4-0321. ------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 2] Observations Description ------------------------ Weak Lensing exploits the distortion of faint background galaxies by the gravitational lensing effect. It directly measures the integrated gravitational tidal field of the cluster, and allows one to reconstruct the full two- dimensional mass distribution. While the physical mechanism is simple, direct and well understood, the application in real observations is complicated by field distortion, point spread function (PSF) anisotropy and calibration issues. These problems are now quite well understood and, in particular, there is now in place a method for analysis of HST images which properly treats the non-trivial shape and variation of the PSF for HST (Kaiser 2000). The number of orbits we are requesting will yield in excess of 100 faint galaxies per square arc-minute, and will thereby provide quite precise mass measurements. The mosaic of field we are proposing is chosen to allow measurement of the gravitational shear out to ~ 2 h_ 50^-1 Mpc and this in turn will allow useful constraint on the mass profile in addition to simple measurements of the total mass. Real Time Justification ----------------------- Of the three massive clusters at z>0.8 known today, two (MS1054.4-0321 and ClJ0152.7 -1357) are already the targets of deep Chandra/ACIS observations (90 and 37 ks, respectively). We here propose a 32 ks ACIS-I observation of the most massive, most distant, and possibly the only virialized of the three, ClJ1226.9+3332. Complementary to the HST/WFPC2 weak-lensing study proposed in the main section of this proposal, the proposed Chandra observation will constrain the gas and dark matter distribution in the cluster core and, specifically, will confirm or refute the presence of a cooling flow. We aim to resolve variations of a factor of two in X-ray surface brightness at 3Sigma significance on scales down to 50 kpc (6 h_50 arcsec at z=0.888), matched to the size of a potential cooling flow of about 150 kpc (radius). We use the ROSAT HRI observation of MS1054.5-0321 to estimate the mean surface brightness in the core region of a massive cluster at z>0.8. Using PIMMS, we convert this HRI surface brightness into a predicted surface brightness with ACIS-I. Using the same surface brightness criterion, but adjusting for differences in Galactic absorption and (estimated) ICM temperature, and scaling by the total X-ray fluxes of MS1054.5-0321 and ClJ1226.9+3332 in the 2--10 keV band, we arrive at a predicted surface brightness of 3.9*10^-5 ct s^-1 arcsec^-2 (ACIS- I, 0.2--10 keV) for ClJ1226.9+3332. Within a circle of 6 arcsec diameter we thus expect an ACIS-I count rate of 1.1*10^-3 ct s^-1, leading to the required exposure time of 32 ks. The proposed observation will yield 2000--3000 photons within a radius of 250 kpc thus allowing us also to determine the temperature in the cluster core region to better than 15% accuracy. The radial gas density profile will be measurable out to at least 500 kpc. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CLJ1226.9+33 CLUSTER OF GALAXIES, RA=12H 26M 58.24S +/- 1.0", J2000 Z = I = 19.5+/-0.5 32 RICH CLUSTER, HIGH DEC=33D 32' 48.3" +/- 1.0" 0.888 REDSHIFT CLUSTER Coordinate Source: Other_Source: DSS2 9033( 17) - 03/04/03 06:26 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE ACS-WFC-DITHER-LINE Pattern_Purpose DITHER DITHER Number_Of_Points 2 2 Point_Spacing 3.011 0.15 Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 85.28 34.13 Center_Pattern YES YES ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 160D TO 164D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG 91.6, 47.9 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG 91.6,-33.8 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 7] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -91.6,-47.9 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 8] Visit: 04 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -91.6, 33.8 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 9] Visit: 05 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -294.7, 50.6 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 10] Visit: 06 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F814W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -294.7,-83.5 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 11] Visit: 07 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG 91.6, 47.9 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 12] Visit: 08 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG 91.6,-33.8 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 13] Visit: 09 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -91.6,-47.9 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 14] Visit: 10 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -91.6, 33.8 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 15] Visit: 11 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC1-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -294.7, 50.6 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 16] Visit: 12 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 CLJ1226.9+3 ACS/WF ACCUM WFC2-FI F606W CR-SPLIT=2 1 1000 S LOW-SKY PATTERN 1 10 POS 332 C X TARG -294.7,-83.5 ------------------------------------------------------------------------------------------------------------------------------------ 9033( 17) - 03/04/03 06:26 - [ 17] Summary Form for Proposal 9033 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1-FIX WFC2-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 160D TO 164D LOW-SKY PATTERN 1 10 POS TARG 91.6, 47.9 SAME ORIENT AS 01 LOW-SKY PATTERN 1 10 POS TARG 91.6,-33.8 LOW-SKY PATTERN 1 10 POS TARG -91.6,-47.9 LOW-SKY PATTERN 1 10 POS TARG -91.6, 33.8 LOW-SKY PATTERN 1 10 POS TARG -294.7, 50.6 LOW-SKY PATTERN 1 10 POS TARG -294.7,-83.5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names CLJ1226.9+3332 ------------------------------------------------------------------------------------------------------------------------------------