15160( 3) - 27-Jul-2017 13:41:56 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15160 Version: 3 Check-in Time: 27-Jul-2017 13:41:56 STScI Edit Number: 0 Title High-resolution imaging of two lensed dusty star-forming galaxies ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrew Baker Rutgers the State University of New Jersey Y CoI: Dr. Megan Gralla The Johns Hopkins University N CoI: Dr. John P. Hughes Rutgers the State University of New Jersey N CoI: Prof. Charles R. Keeton Rutgers the State University of New Jersey N CoI: Prof. Tobias Marriage The Johns Hopkins University N CoI: Jesus Rivera Rutgers the State University of New Jersey N CoI: Mr. Cristobal Sifon Princeton University N CoI: Mr. Amitpal Tagore Rutgers the State University of New Jersey N CoI: Dr. Roberto Decarli Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Dr. Fabian Walter Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Dr. Axel Weiss Max-Planck-Institut fur Radioastronomie N CoI: Dr. Katherine Anne Alatalo Carnegie Institution of Washington N ------------------------------------------------------------------------------------ Abstract Dusty star-forming galaxies (DSFGs) make significant contributions to the star formation history of the universe, but the same dust that powers their luminosity obscures much or all of the rest-UV and optical light that would allow easy study of their dynamical properties and evolutionary states. In this proposal, we request observations of two DSFGs that are among the brightest point sources in three-band mapping with the Atacama Cosmology Telescope (ACT), both of which show incontrovertible evidence of gravitational lensing. From HST imaging, we will extract information about the background sources and lens-plane structures and develop gravitational lens models, thereby gaining insights into the DSFGs' intrinsic sizes, morphologies, and gas masses and kinematics, and into the presence of substructure in the lens plane. This effort will be strengthened by the fact that both of our targets already have highly resolved mid-J CO mapping with the IRAM Northern Extended Millimeter Array; in these cases, each independent velocity channel serves as an independent probe of the lensing potential. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will use the F160W (~ H) filter on WFC3/IR to maximize sensitivity to the redshifted emission of the background DSFGs in our sample. We will use the standard WFC3-IR-DITHER-BOX-MIN pattern with four positions in order to optimally sample the PSF. The field of view of interest for each target will be well contained within the optimally sampled region. For both targets, there is good evidence for emission in this band from ground-based images. This evidence is clear for ACT-S-J2029+0120 (Roberts-Borsani et al. 2017), while there are hints of spatially extended emission in H-band imaging of ACT-S-J0116-0004. 15160( 3) - 27-Jul-2017 13:41:56 - [ 2] We estimated the range of surface brightness of the background lensed galaxy using H-band imaging from the VISTA Hemispheric Survey (VHS) for ACT-S-J0116-0004, and SDSS r-band and our own APO Ks-band image for ACT-S-J2029+0120. In each case, the lensed galaxy was modeled using Galfit (Peng et al. 2002, 2010). After the fit converged, the model was subtracted from the data and the residuals were used to estimate a mean and maximum surface brightness for the background galaxy. With estimated lens galaxy magnitudes in the range H = 14.6-17.6 and background galaxy surface brightnesses in the range 19.1-23.2 mag/arcsec^2 (Vega-relative), we need to ensure that the WFC3/IR images have adequate dynamic range, and are therefore using the STEP50 sequence with NSAMP = 11 to obtain eight 299.232s sub-exposures (via two executions of the four-position dither pattern). The resulting integration time per object (2393.856s) should yield a detection signal-to-noise ratio of >10 in a 5x5 pixel box for our faintest expected surface brightness value (23.2 mag/arcsec^2), based on the output of the WFC3/IR imaging ETC for a diffuse source with an elliptical galaxy spectrum and nominal background conditions. This depth will ensure high signal-to-noise over many square arcseconds of the background sources, as required by the proposal's scientific goals, and will allow even higher-S/N characterization of the main lensing galaxies and any satellites in their vicinities. ------------------------------------------------------------------------------------ 15160( 3) - 27-Jul-2017 13:41:56 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ACT-S-J0116- GALAXY, GRAVITATIONAL RA=01H16M40.1400S +/- 0.1", J2000 J = 18.4, H = 17.6, Ks = 17.2 0004 LENS, HIGH REDSHIFT DEC=-00D04'53.60" +/- 0.1" GALAXY Reference Frame: ICRS Comments: Coordinates based on NOEMA imaging. The star nearest to the DSFG is farther away than our adopted dither pattern steps, so image persistence will not be a problem in the vicinity of our science target. ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-S-J2029+ GALAXY, GRAVITATIONAL RA=20H29M55.5000S +/- 0.1", J2000 J = 15.5, H = 14.6, Ks = 14.3 0120 LENS, HIGH REDSHIFT DEC=+01D20'58.90" +/- 0.1" GALAXY Reference Frame: ICRS Comments: Target coordinates based on NOEMA imaging. The star nearest to the DSFG is farther away than our adopted dither pattern steps, and the nearest very bright star (2MASS J20295151+0120417, with J = 10.29, H = 10.032, K = 10.0) is 62" away near the edge of the FOV, so image persistence will not be a problem in the vicinity of our science target. ------------------------------------------------------------------------------------------------------------------------------------ 15160( 3) - 27-Jul-2017 13:41:56 - [ 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 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15160( 3) - 27-Jul-2017 13:41:56 - [ 5] Visit: 01 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 ACT-S-J0116 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 1 -0004 CUM (1196.93 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-S-J0116 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 2 -0004 CUM (1196.93 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 | ------------------------------------------------------------------------------------------------------------------------------------ ACT-S-J0116-0004 1 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM ACT-S-J0116-0004 1 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM ACT-S-J0116-0004 1 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM ACT-S-J0116-0004 1 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM ACT-S-J0116-0004 2 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM ACT-S-J0116-0004 2 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM ACT-S-J0116-0004 2 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM ACT-S-J0116-0004 2 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM 15160( 3) - 27-Jul-2017 13:41:56 - [ 6] Visit: 02 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 ACT-S-J2029 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 1 +0120 CUM (1196.93 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ACT-S-J2029 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 2 +0120 CUM (1196.93 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 | ------------------------------------------------------------------------------------------------------------------------------------ ACT-S-J2029+0120 1 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM ACT-S-J2029+0120 1 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM ACT-S-J2029+0120 1 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM ACT-S-J2029+0120 1 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM ACT-S-J2029+0120 2 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM ACT-S-J2029+0120 2 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM ACT-S-J2029+0120 2 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM ACT-S-J2029+0120 2 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM 15160( 3) - 27-Jul-2017 13:41:56 - [ 7] Summary Form for Proposal 15160 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=11, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ACT-S-J0116-0004, ACT-S-J2029+0120 ------------------------------------------------------------------------------------------------------------------------------------