16428( 3) - 18-Sep-2020 22:58:16 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16428 Version: 3 Check-in Time: 18-Sep-2020 22:58:16 STScI Edit Number: 0 Title Keep It Simple: Massive Two-Body Mergers at z~0.6 ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Harald Ebeling University of Hawaii Y CoI: Dr. Alastair C. Edge Durham Univ. N CoI: Mr. Lukas Zalesky University of Hawaii N CoI: Dr. Johan Pierre Richard Centre de Recherche Astrophysique de Lyon N ------------------------------------------------------------------------------------ Abstract Major mergers are pivotal events in the formation of large-scale structure that mark the creation of the most massive galaxy clusters of their epoch. At z>0.5, they are signposts of the first such systems to have formed in the Universe. We propose an exploratory Chandra/HST study of two massive mergers at z>0.5, discovered by the eMACS project and carefully selected to feature a simple, two-body geometry, in order to determine the merger phase (pre- or post-collision), global X-ray properties, and strong-lensing power, thereby assessing their potential for future, in-depth lensing and structure evolution studies. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our target already has partial coverage with HST, obtained as part of a longstanding SNAPshot program on eMACS clusters (PI: Ebeling). To complete the required 4-filter coverage (from the near-UV to 1 micron in the cluster restframe) eMACSJ0502 still needs critically important imaging with ACS in the F814W passband. A single orbit will suffice to allow the secure confirmation and further identification of multiple-image lensing features based on their matching morphology and matching colors. The F814W passband lies fully redward of the D4000A break at the cluster redshift, thus providing critical color information to distinguish between cluster members and lensed background galaxies. The requested one-orbit F814W observation of eMACSJ0502 (dithered to allow the removal of cosmic rays and to fill in the ACS chip gap) matches the depth of the F606W data already in hand for our target. The full 4-filter data set will not only facilitate the identification of lensing features, but will also provide valuable information on the galaxy population of the cluster, highlighting ram-pressure stripping events as well as star formation and dust in the BCGs. ------------------------------------------------------------------------------------ 16428( 3) - 18-Sep-2020 22:58:16 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 EMACSJ0502.9 CLUSTER OF GALAXIES, RA=05H02M54.4000S, J2000 V = 21 -2902 GRAVITATIONAL LENS, DEC=-29D02'22.00" RICH CLUSTER Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16428( 3) - 18-Sep-2020 22:58:16 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE ACS-WFC-DITHER-LINE Pattern_Purpose DITHER DITHER Number_Of_Points 2 2 Point_Spacing 3.034 0.262 Line_Spacing Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 85.29 18.39 Angle_Between_Sides Center_Pattern NO NO ------------------------------------------------------------------------------------------------------------------------------------ 16428( 3) - 18-Sep-2020 22:58:16 - [ 4] Visit: 01 (e0502-f814w) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EMACSJ0502. ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 520 S PATTERN 1 1 9-2902 (2080 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EMACSJ0502.9-2902 1 ACS/WFC ACCUM WFC F814W 1 1 none none 1 N/A EMACSJ0502.9-2902 1 ACS/WFC ACCUM WFC F814W 1 2 none none 1 N/A EMACSJ0502.9-2902 1 ACS/WFC ACCUM WFC F814W 2 1 none none 1 N/A EMACSJ0502.9-2902 1 ACS/WFC ACCUM WFC F814W 2 2 none none 1 N/A 16428( 3) - 18-Sep-2020 22:58:16 - [ 5] Summary Form for Proposal 16428 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names EMACSJ0502.9-2902 ------------------------------------------------------------------------------------------------------------------------------------