15919( 2) - 18-Jul-2019 13:43:04 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15919 Version: 2 Check-in Time: 18-Jul-2019 13:43:04 STScI Edit Number: 0 Title Rise of the Titans: Unveiling the Nature of a Binary Hyper-Luminous Starburst at Redshift 6 ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Dominik A. Riechers Cornell University Y CoI: Dr. Ismael Perez-Fournon Instituto de Astrofisica de Canarias N CoI: Prof. Rob Ivison Royal Observatory Edinburgh N CoI: Dr. Ivan Oteo University of Edinburgh, Institute for N Astronomy CoI: Dr. David Clements Imperial College of Science Technology and N Medicine CoI: Prof. Asantha R Cooray University of California - Irvine N CoI: Dr. Duncan Farrah University of Hawaii N CoI: Rui Marques-Chaves Centro de Astrobiologia (CSIC/INTA) Inst. N Nac. de Tec. Aero. CoI: Dr. Seb Oliver University of Sussex N CoI: Dr. Axel Weiss Max-Planck-Institut fur Radioastronomie N CoI: Prof. Douglas Scott University of British Columbia N ------------------------------------------------------------------------------------ Abstract We propose HST/WFC3-IR and ACS observations in 3 bands to characterize the nature and the environment of ADFS-27, the most distant binary hyper-luminous starburst known, at a redshift of 5.655. This rare, gas-rich (Mgas~2.5x10^11Msun), dusty starburst (SFR~2500Msun/yr) system was recently discovered with ALMA and Herschel. It consists of two merging galaxies ~2kpc in diameter with dynamical masses of >3x10^11Msun each, separated by only 9kpc, resolved in dust emission by ALMA at 0.15" (1kpc) resolution. We here request imaging of the rest-frame ultraviolet light at matching resolution to measure the unobscured star formation rate, stellar mass and star formation history of this system through a complete SED analysis, as well as the morphology and sizes of the stellar disks and the UV extinction profile. We will also use the multi-band data to search for dropout galaxies in its environment on Mpc scales using the Lyman-break technique, which will put constraints on its formation history and the dark matter halo mass scale. This investigation could reveal the presence of a massive proto-cluster of galaxies within the first billion years of the Big Bang. Finally, the HST imaging will unambiguously address the possibility of a weak gravitational magnification of this system. Given its extreme cosmic rarity, this is key to properly place the existence and evolution of ADFS-27 into context with cosmological simulations and models of starburst galaxies at different epochs. This study will be an important pathfinder for detailed investigations of the most exceptional star-forming environments in the early universe with JWST. ------------------------------------------------------------------------------------ Observations Description ------------------------ Program uses 5 orbits, 3 with WFC3/IR in the F098M and F160W filters, and 2 15919( 2) - 18-Jul-2019 13:43:04 - [ 2] with ACS/WFC and the F606W filter. It is broken up into two visits, one consisting of the two ACS orbits, and the other consisting of the three WFC3 IR orbits (concatenated to ensure similar rotation angles between orbits, and thus, coverage of the same galaxies in both filters - this is not an issue for ACS, given the much larger field of view relative to WFC3, it will cover the full area of interest at any orientation angle). There is no restriction on the orientation angle. All observations are of the same target field (ADFS27). 4-point position/readout dither patterns are employed, primarily to improve the PSF through subpixel sampling, i.e., to mitigate the effects of the large detector pixel sizes (especially for WFC3/IR), as well as to offset by a sufficiently large amount to move persistent pixels to different locations on the sky in each exposure, and to provide good cosmic ray rejection. For ACS/WFC, this is also important to cover the 50 pixel gap in y direction between the two detector chips. The ACS/WFC dither pattern consists of 2 positions with offset large enough to cover the inter-chip gap, and 2 subpositions each to dither on subpixel scales. The WFC3/IR dither patterns consist of 2 postions large enough to cover the "death star" feature, and 2 subpositions each to dither on subpixel scales. For the one F098M orbit, 4 positions are targeted. For the two F160W orbits, each orbit contains two subpixel dither positions, and the larger re-positioning is done between orbits. ------------------------------------------------------------------------------------ 15919( 2) - 18-Jul-2019 13:43:04 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ADFS27 GALAXY, HIGH REDSHIFT RA=04H36M57.0300S +/- 0.1", J2000 V = 27 +/- 0.5 GALAXY, INTERACTING DEC=-54D38'9.00" +/- 0.1" GALAXY, STARBURST, ULTRALUMINOUS IR GAL Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 15919( 2) - 18-Jul-2019 13:43:04 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE LINE Pattern_Purpose DITHER BACKGROUND Number_Of_Points 2 2 Point_Spacing 3.011 0.149 Line_Spacing Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 85.28 34.25 Angle_Between_Sides Center_Pattern NO NO ------------------------------------------------------------------------------------------------------------------------------------ 15919( 2) - 18-Jul-2019 13:43:04 - [ 5] Visit: 01 (ACS-F606W) 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 ADFS27 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 2 549 S PATTERN 1 1 see below (4800 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 | ------------------------------------------------------------------------------------------------------------------------------------ ADFS27 1 ACS/WFC ACCUM WFC F606W 1 1 1 none 1 586.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 1 1 2 none 1 586.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 1 2 1 none 1 586.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 1 2 2 none 1 586.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 2 1 1 none 2 614.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 2 1 2 none 2 614.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 2 2 1 none 2 614.0 S ADFS27 1 ACS/WFC ACCUM WFC F606W 2 2 2 none 2 614.0 S 15919( 2) - 18-Jul-2019 13:43:04 - [ 6] Visit: 02 (WFC3-IR) 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 ADFS27 WFC3/IR MULTIAC IR-FIX F098M NSAMP=8, SAMP-SEQ=SPARS100 1 DEF POS TARG -3.3875, CUM (702.935 -3.0275 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ADFS27 WFC3/IR MULTIAC IR-FIX F098M NSAMP=8, SAMP-SEQ=SPARS100 1 DEF POS TARG -3.8615, CUM (702.935 -3.4515 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ADFS27 WFC3/IR MULTIAC IR-FIX F098M NSAMP=7, SAMP-SEQ=SPARS100 1 DEF POS TARG 3.3875, 3.0275 CUM (602.934 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ADFS27 WFC3/IR MULTIAC IR-FIX F098M NSAMP=8, SAMP-SEQ=SPARS100 1 DEF POS TARG 3.8615, 3.4515 CUM (702.935 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 ADFS27 WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=SPARS100 1 DEF POS TARG -3.3875, CUM (1402.937 -3.0275 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ADFS27 WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=SPARS100 1 DEF POS TARG -3.8615, CUM (1402.937 -3.4515 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ADFS27 WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=SPARS100 1 DEF POS TARG 3.3875, 3.0275 CUM (1402.937 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ADFS27 WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=SPARS100 1 DEF POS TARG 3.8615, 3.4515 CUM (1402.937 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 | ------------------------------------------------------------------------------------------------------------------------------------ ADFS27 1 WFC3/IR MULTIAC IR-FIX F098M none none none none 1 N/A CUM ADFS27 2 WFC3/IR MULTIAC IR-FIX F098M none none none none 1 N/A CUM 15919( 2) - 18-Jul-2019 13:43:04 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ADFS27 3 WFC3/IR MULTIAC IR-FIX F098M none none none none 1 N/A CUM ADFS27 4 WFC3/IR MULTIAC IR-FIX F098M none none none none 1 N/A CUM ADFS27 5 WFC3/IR MULTIAC IR-FIX F160W none none none none 2 N/A CUM ADFS27 6 WFC3/IR MULTIAC IR-FIX F160W none none none none 2 N/A CUM ADFS27 7 WFC3/IR MULTIAC IR-FIX F160W none none none none 3 N/A CUM ADFS27 8 WFC3/IR MULTIAC IR-FIX F160W none none none none 3 N/A CUM 15919( 2) - 18-Jul-2019 13:43:04 - [ 8] Summary Form for Proposal 15919 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO, NSAMP=15, NSAMP=7, NSAMP=8, SAMP-SEQ=SPARS100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, POS TARG -3.3875, -3.0275, POS TARG -3.8615, -3.4515, POS TARG 3.3875, 3.0275, POS TARG 3.8615, 3.4515 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F098M, F160W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ADFS27 ------------------------------------------------------------------------------------------------------------------------------------