16504( 4) - 11-Aug-2021 20:20:25 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16504 Version: 4 Check-in Time: 11-Aug-2021 20:20:25 STScI Edit Number: 1 Title A Spectroscopically Confirmed Massively Star-forming Protocluster at z = 3.14 ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Michael Jacob Rosenthal University of Wisconsin - Madison Y CoI: Mr. Logan Houston Jones University of Wisconsin - Madison N CoI: Dr. Amy J. Barger University of Wisconsin - Madison N CoI: Dr. Lennox L. Cowie University of Hawaii N ------------------------------------------------------------------------------------ Abstract Dense protoclusters of bright submillimeter galaxies are the suspected progenitors of today's massive clusters, but the mechanisms that govern their triggering and transition to compact quiescent galaxies by z ~ 2 are not well understood. These processes are hinted at by millimeter spectral line profiles, but are only fully resolved at sub-arcsecond scales, which cannot be imaged efficiently with ground-based telescopes in the Northern hemisphere. We propose to constrain the morphology of the stars in the two submillimeter-brightest galaxies in a newly identified, spectroscopically confirmed protocluster at z = 3.14. This requires 5 total orbits with WFC3-IR, with 3 orbits with F110W and 2 orbits with F160W. The protocluster lies in the GOODS-North and has extensive multi-wavelength coverage, but is just outside the coverage of HST/ACS and WFC3 from the original GOODS and CANDELS surveys, such that no sufficiently high-resolution imaging of this field currently exists. The two galaxies have spectroscopic redshifts from CO line scans with NOEMA, but their CO(5-4) line profiles are different, suggesting different stages or mechanisms of triggering. The 0.15'' resolution of the proposed observations will resolve close mergers and/or compact stellar counterparts. Our ~9 square arminute coverage will also serendipitously detect the near-IR counterparts of many fainter submillimeter galaxies in this dense field. The identification of advanced mergers or compact stellar counterparts in these galaxies, which can trace ongoing triggering or quenching, respectively, will be used to prioritize targets for high-resolution millimeter interferometric follow-up. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain deep images of the counterparts of the four brightest SMGs in the protocluster field with the infrared channel of WFC3 in the F110W and F160W filters, to identify the extent and morphology of their stellar populations. These include GN-CL-2 and GN-CL-3, the two spectroscopically confirmed protocluster members. These galaxies are separated by more than the size of the WFC3 IR channel FoV, so we request two pointings: a northern pointing containing GN-CL-2 alone, and a southern pointing containing GN-CL-3. Splitting the observations into two pointings is necessary to avoid a bright star (2MASS J=8.34, H=7.77) in the field, which has saturated a portion of the CFHT/WIRCam images near GN-CL-1 and GN-CL-2. Our specified pointings avoid this bright star, and our orientation ranges should prevent diffraction spikes from 16504( 4) - 11-Aug-2021 20:20:25 - [ 2] interfering with our imaging. We estimated exposure times using the WFC3-IR imaging calculator in F110W and F160W. We assumed that GN-CL-2 and GN-CL-3 have half-light radii of ~2.8 kpc, or 0.36 arcsec at z = 3.14, and used existing CFHT/WIRCam J and H photometry to estimate their brightnesses. We break our observations up into four visits, with each one observing a single pointing in a single filter. The visit containing the F110W imaging of GN-CL-3 will consist of two orbits, and each of the other three visits will consist of one orbit each. These are sufficient to reach a S/N of 5 per pixel. We will use a modified WFC3-IR-DITHER-BOX-MIN dithering pattern (pattern E4 in WFC3 IRS 2010-09) to sub-sample the PSF and step over IR blobs. Although none of our main science targets are positioned on IR blobs or the Death Star, we include this large step to maximize image quality over the whole field, given many galaxies in the WFC3 FoV may be protocluster members. ------------------------------------------------------------------------------------ 16504( 4) - 11-Aug-2021 20:20:25 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GNCL-NORTH CLUSTER OF GALAXIES, RA=12H35M52.6550S, J2000 Z = V = 24.6 +/- 0.2 J=24.0, H=23.4 (AB). HIGH REDSHIFT CLUSTER DEC=+62D23'22.73" 3.148 Reference Frame: ICRS Comments: Coordinates are for the center of the field, which contains several submillimeter galaxies. The brightest target galaxy GN-CL-2 is at 12:35:55.88 +62:22:39.0 (+/- 2 arcsec in both RA and Dec). J and H magnitudes are for this galaxy. ------------------------------------------------------------------------------------------------------------------------------------ 2 GNCL-SOUTH CLUSTER OF GALAXIES, RA=12H35M46.6158S, J2000 Z = V = 26.1 +/- 0.4 J=25.0, H=24.0 (AB) HIGH REDSHIFT CLUSTER DEC=+62D21'8.91" 3.133 Reference Frame: ICRS Comments: Coordinates are for the center of the field, which contains several submillimeter galaxies. The brightest target galaxy GN-CL-3 is at 12:35:46.64 +62:20:13.3 (+/- 2 arcsec in both RA and Dec). J and H magnitudes are for this galaxy. Also contains GN-CL-1 at 12:35:51.37 +62:21:47.2 (z=4.422) and GN-CL-4 at 12:35:39.9 +62:21:29 (z unknown). ------------------------------------------------------------------------------------------------------------------------------------ 16504( 4) - 11-Aug-2021 20:20:25 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.384 Line_Spacing 4.793 Coordinate_Frame POS-TARG Pattern_Orient 331.798 Angle_Between_Sides 288.391 Center_Pattern NO Pattern_Comments: WFC3 ISR 2010-09 IR pattern E4 ------------------------------------------------------------------------------------------------------------------------------------ 16504( 4) - 11-Aug-2021 20:20:25 - [ 5] Visit: 01 (CL2 F160W) Visit Requirements: ORIENT 35D TO 55 D; ORIENT 215D TO 235 D 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 GNCL-NORTH WFC3/IR MULTIAC IR-FIX F160W NSAMP=14, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 CUM (2623.512 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 | ------------------------------------------------------------------------------------------------------------------------------------ GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 1 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 1 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 2 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 2 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 3 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 3 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 4 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR-FIX F160W 4 none 2 none 1 N/A CUM 16504( 4) - 11-Aug-2021 20:20:25 - [ 6] Visit: 02 (CL3 F160W) Visit Requirements: ORIENT 75D TO 95 D; ORIENT 255D TO 275 D 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 GNCL-SOUTH WFC3/IR MULTIAC IR F160W NSAMP=14, SAMP-SEQ=SPARS25 2 DEF PATTERN 1 1 CUM (2623.512 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 | ------------------------------------------------------------------------------------------------------------------------------------ GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 1 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 1 none 2 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 2 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 2 none 2 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 3 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 3 none 2 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 4 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F160W 4 none 2 none 1 N/A CUM 16504( 4) - 11-Aug-2021 20:20:25 - [ 7] Visit: 03 (CL2 F110W) Visit Requirements: ORIENT 35D TO 55 D; ORIENT 215D TO 235 D 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 GNCL-NORTH WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS25 2 DEF GS ACQ SCENARIO BASE1B3; CUM (2623.512 PATTERN 1 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 1 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 1 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 2 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 2 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 3 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 3 none 2 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 4 none 1 none 1 N/A CUM GNCL-NORTH 1 WFC3/IR MULTIAC IR F110W 4 none 2 none 1 N/A CUM 16504( 4) - 11-Aug-2021 20:20:25 - [ 8] Visit: 04 (CL3 F110W) Visit Requirements: ORIENT 75D TO 95 D; ORIENT 255D TO 275 D 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 GNCL-SOUTH WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS25 4 DEF PATTERN 1 1 CUM (5247.024 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 | ------------------------------------------------------------------------------------------------------------------------------------ GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 1 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 1 none 2 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 1 none 3 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 1 none 4 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 2 none 1 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 2 none 2 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 2 none 3 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 2 none 4 none 1 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 3 none 1 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 3 none 2 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 3 none 3 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 3 none 4 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 4 none 1 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 4 none 2 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 4 none 3 none 2 N/A CUM GNCL-SOUTH 1 WFC3/IR MULTIAC IR F110W 4 none 4 none 2 N/A CUM 16504( 4) - 11-Aug-2021 20:20:25 - [ 9] Summary Form for Proposal 16504 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=14, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, ORIENT 215D TO 235 D, ORIENT 255D TO 275 D, ORIENT 35D TO 55 D, ORIENT 75D TO 95 D, PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GNCL-NORTH, GNCL-SOUTH ------------------------------------------------------------------------------------------------------------------------------------