16756( 4) - 15-Feb-2022 17:00:18 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16756 Version: 4 Check-in Time: 15-Feb-2022 17:00:18 STScI Edit Number: 2 Title Quasars with small proximity zones: gravitationally lensed or exceptionally young? ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Anna-Christina Eilers Massachusetts Institute of Technology Y CoI: Dr. Sandro Tacchella Smithsonian Institution Astrophysical N Observatory CoI: Dr. Frederick Davies Max Planck Institute for Astronomy N CoI: Prof. Robert Andrew Simcoe Massachusetts Institute of Technology N CoI: Dr. Julian B. Munoz Smithsonian Institution Astrophysical N Observatory CoI: Dr. Charlotte Mason University of Copenhagen, Niels Bohr N Institute CoI: Dr. Sirio Belli Smithsonian Institution Astrophysical N Observatory CoI: Dr. Erica Nelson University of Colorado at Boulder N CoI: Prof. Joseph Hennawi University of California - Santa Barbara N ------------------------------------------------------------------------------------ Abstract The existence of luminous quasars hosting supermassive black holes (SMBHs) within the first billion years of cosmic history challenges our understanding of black hole growth. However, much of our understanding relies on the assumption that the observed luminosities are intrinsic to the quasars themselves. It has long been predicted that a large fraction of high-redshift quasars should be gravitationally lensed, but to date only one lensed quasar above z>5 has been confirmed despite considerable observational efforts. We propose to search for this long sought-after population of lensed quasars with HST/ACS, targeting six objects at z~6 whose rest-frame UV spectra exhibit exceptionally small proximity zones. These quasars are excellent candidates for being gravitationally lensed objects, because the local ionizing flux implied by their small proximity zones is far below the expectation from their observed UV luminosities. We aim to apply a two-fold observing strategy using imaging both in the near-IR to search for multiple quasar images, as well as in the optical regime to target foreground lensing galaxies using the intergalactic medium as a natural long-pass filter to avoid the quasar light, in order to improve the success rate of this lensing search. In case we do not find evidence for lensing, the quasars' small proximity zones could be explained by very short UV-luminous lifetimes of less than 10, 000 years, requiring either super-Eddington accretion rates or highly obscured black hole growth phases, in order to explain the concomitant SMBH growth. Thus either outcome of our proposed observations promises new insights into the formation and growth of the first SMBHs. ------------------------------------------------------------------------------------ Observations Description ------------------------ We aim to tagert six quasars at z~6 with ACS/WFC in two different filters, i.e. F892N and F555W. Data taken with the F892N filter will capture the 16756( 4) - 15-Feb-2022 17:00:18 - [ 2] quasarrest-frame UV continuum emission and will search for multiple images of the quasar at small angular separations. Observations with the wide F555W filter will search the foreground of the quasars for potential lensing galaxies along the quasar sightline without any contamination from the quasar itself, since the filter is chosen to be at lower wavelengths than the Lyman-limit. We aim to observe each quasar for 2 orbits, one orbit for each filter (apart from target 02, i.e. SDSSJ1335+3533, which has already archival HST data with the filter F105W on WFC3-IR, program ID: #12184, resulting in a similar angular resolution). This implies that each visit consists of 1-2 orbits, ensuring easy schedulability of the program. We split each orbit into 4 exposures applying the dither pattern ACS-WFC-DITHER-BOX, which was selected as a minimally compact arrangement that provides half-integer pixel dither steps that will allow for an improved PSF reconstruction in the drizzled stack. The exposure time of ~520s per dither position is chosen to maximize the orbital visibilities used. This will allow us to detect any foreground galaxies down to a magnitude of m_AB~28 mag (~95% completeness) with >4.3 sigma significance. The chosen longer wavelength filter F892N with a central wavelength of lambda = 8915 A will image the rest-frame UV continuum emission of the quasar and enable the detection of multiple quasar images with an diffraction-limited angular resolution of approximately 0.076''. We chose the aperture WFC1, since it is in the middle of one of the two detectors avoiding potential issues with the detector gap, but nevertheless capturing all potentially lensing foreground galaxies at impact parameters of <100 arcsec from the quasar sightline, which is far more than required. We have no orientation or timing requirements. ------------------------------------------------------------------------------------ 16756( 4) - 15-Feb-2022 17:00:18 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PSOJ004+17 GALAXY, QSO, QUASAR RA=00H17M34.4670S, J2000 Z = V = 26 +/- 2 z_AB = 20.82+-0.07 DEC=+17D05'10.70" 5.8166 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ1335+35 GALAXY, QSO, QUASAR RA=13H35M50.8070S, J2000 Z = V = 26 +/- 2 z_AB = 20.10+-0.11 33 DEC=+35D33'15.80" 5.9012 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 PSOJ158-14 GALAXY, QSO, QUASAR RA=10H34M46.5090S, J2000 Z = V = 26 +/- 2 z_AB = 19.44+-0.08 DEC=-14D25'15.85" 6.0685 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 4 CFHQSJ2100-1 GALAXY, QSO, QUASAR RA=21H00M54.6160S, J2000 Z = V = 26 +/- 2 z_AB = 22.35+-0.09 715 DEC=-17D15'22.50" 6.0806 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 5 CFHQSJ2229+1 GALAXY, QSO, QUASAR RA=22H29M1.6490S, J2000 Z = V = 26 +/- 2 z_AB = 22.03+-0.05 457 DEC=+14D57'8.98" 6.1517 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 6 VDESJ0330-40 GALAXY, QSO, QUASAR RA=03H30M27.9200S, J2000 Z = V = 26 +/- 2 z_AB = 20.66+-0.02 25 DEC=-40D25'16.20" 6.249 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16756( 4) - 15-Feb-2022 17:00:18 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.262 Line_Spacing 0.192 Coordinate_Frame POS-TARG Pattern_Orient 18.39 Angle_Between_Sides 68.14 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16756( 4) - 15-Feb-2022 17:00:18 - [ 5] Visit: 01 (ACS-WFC_imaging_PSOJ004+17) 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 PSOJ004+17 ACS/WFC ACCUM WFC1 F850LP FLASH=10 1 470 S PATTERN 1 1 see below (2056 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 PSOJ004+17 ACS/WFC ACCUM WFC1 F555W 1 460 S PATTERN 1 2 see below (2120 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 | ------------------------------------------------------------------------------------------------------------------------------------ PSOJ004+17 1 ACS/WFC ACCUM WFC1 F850LP 1 none none none 1 514.0 S PSOJ004+17 1 ACS/WFC ACCUM WFC1 F850LP 2 none none none 1 514.0 S PSOJ004+17 1 ACS/WFC ACCUM WFC1 F850LP 3 none none none 1 514.0 S PSOJ004+17 1 ACS/WFC ACCUM WFC1 F850LP 4 none none none 1 514.0 S PSOJ004+17 2 ACS/WFC ACCUM WFC1 F555W 1 none none none 2 530.0 S PSOJ004+17 2 ACS/WFC ACCUM WFC1 F555W 2 none none none 2 530.0 S PSOJ004+17 2 ACS/WFC ACCUM WFC1 F555W 3 none none none 2 530.0 S PSOJ004+17 2 ACS/WFC ACCUM WFC1 F555W 4 none none none 2 530.0 S 16756( 4) - 15-Feb-2022 17:00:18 - [ 6] Visit: 02 (ACS-WFC_imaging_J1335+3533) 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 SDSSJ1335+3 ACS/WFC ACCUM WFC1 F555W 1 530 S PATTERN 1 1 533 (2120 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 1 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 2 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 3 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 4 none none none 1 N/A 16756( 4) - 15-Feb-2022 17:00:18 - [ 7] Visit: 03 (ACS-WFC_imaging_PSOJ158-14) 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 PSOJ158-14 ACS/WFC ACCUM WFC1 F850LP FLASH=10 1 466 S PATTERN 1 1 see below (2052 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 PSOJ158-14 ACS/WFC ACCUM WFC1 F555W 1 470 S PATTERN 1 2 see below (2116 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 | ------------------------------------------------------------------------------------------------------------------------------------ PSOJ158-14 1 ACS/WFC ACCUM WFC1 F850LP 1 none none none 1 513.0 S PSOJ158-14 1 ACS/WFC ACCUM WFC1 F850LP 2 none none none 1 513.0 S PSOJ158-14 1 ACS/WFC ACCUM WFC1 F850LP 3 none none none 1 513.0 S PSOJ158-14 1 ACS/WFC ACCUM WFC1 F850LP 4 none none none 1 513.0 S PSOJ158-14 2 ACS/WFC ACCUM WFC1 F555W 1 none none none 2 529.0 S PSOJ158-14 2 ACS/WFC ACCUM WFC1 F555W 2 none none none 2 529.0 S PSOJ158-14 2 ACS/WFC ACCUM WFC1 F555W 3 none none none 2 529.0 S PSOJ158-14 2 ACS/WFC ACCUM WFC1 F555W 4 none none none 2 529.0 S 16756( 4) - 15-Feb-2022 17:00:18 - [ 8] Visit: 04 (ACS-WFC_imaging_J2100-1715) 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 CFHQSJ2100- ACS/WFC ACCUM WFC1 F850LP FLASH=10 1 400 S PATTERN 1 1 1715 see below (2056 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CFHQSJ2100- ACS/WFC ACCUM WFC1 F555W 1 400 S PATTERN 1 2 1715 see below (2120 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 | ------------------------------------------------------------------------------------------------------------------------------------ CFHQSJ2100-1715 1 ACS/WFC ACCUM WFC1 F850LP 1 none none none 1 514.0 S CFHQSJ2100-1715 1 ACS/WFC ACCUM WFC1 F850LP 2 none none none 1 514.0 S CFHQSJ2100-1715 1 ACS/WFC ACCUM WFC1 F850LP 3 none none none 1 514.0 S CFHQSJ2100-1715 1 ACS/WFC ACCUM WFC1 F850LP 4 none none none 1 514.0 S CFHQSJ2100-1715 2 ACS/WFC ACCUM WFC1 F555W 1 none none none 2 530.0 S CFHQSJ2100-1715 2 ACS/WFC ACCUM WFC1 F555W 2 none none none 2 530.0 S CFHQSJ2100-1715 2 ACS/WFC ACCUM WFC1 F555W 3 none none none 2 530.0 S CFHQSJ2100-1715 2 ACS/WFC ACCUM WFC1 F555W 4 none none none 2 530.0 S 16756( 4) - 15-Feb-2022 17:00:18 - [ 9] Visit: 05 (ACS-WFC_imaging_J2229+1457) 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 CFHQSJ2229+ ACS/WFC ACCUM WFC1 F850LP FLASH=10 1 400 S PATTERN 1 1 1457 see below (2052 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CFHQSJ2229+ ACS/WFC ACCUM WFC1 F555W 1 400 S PATTERN 1 2 1457 see below (2116 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 | ------------------------------------------------------------------------------------------------------------------------------------ CFHQSJ2229+1457 1 ACS/WFC ACCUM WFC1 F850LP 1 none none none 1 513.0 S CFHQSJ2229+1457 1 ACS/WFC ACCUM WFC1 F850LP 2 none none none 1 513.0 S CFHQSJ2229+1457 1 ACS/WFC ACCUM WFC1 F850LP 3 none none none 1 513.0 S CFHQSJ2229+1457 1 ACS/WFC ACCUM WFC1 F850LP 4 none none none 1 513.0 S CFHQSJ2229+1457 2 ACS/WFC ACCUM WFC1 F555W 1 none none none 2 529.0 S CFHQSJ2229+1457 2 ACS/WFC ACCUM WFC1 F555W 2 none none none 2 529.0 S CFHQSJ2229+1457 2 ACS/WFC ACCUM WFC1 F555W 3 none none none 2 529.0 S CFHQSJ2229+1457 2 ACS/WFC ACCUM WFC1 F555W 4 none none none 2 529.0 S 16756( 4) - 15-Feb-2022 17:00:18 - [ 10] Visit: 06 (ACS-WFC_imaging_J0330-4025) 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 VDESJ0330-4 ACS/WFC ACCUM WFC1 F850LP FLASH=10 1 400 S PATTERN 1 1 025 see below (2140 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 VDESJ0330-4 ACS/WFC ACCUM WFC1 F555W 1 400 S PATTERN 1 2 025 see below (2204 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 | ------------------------------------------------------------------------------------------------------------------------------------ VDESJ0330-4025 1 ACS/WFC ACCUM WFC1 F850LP 1 none none none 1 535.0 S VDESJ0330-4025 1 ACS/WFC ACCUM WFC1 F850LP 2 none none none 1 535.0 S VDESJ0330-4025 1 ACS/WFC ACCUM WFC1 F850LP 3 none none none 1 535.0 S VDESJ0330-4025 1 ACS/WFC ACCUM WFC1 F850LP 4 none none none 1 535.0 S VDESJ0330-4025 2 ACS/WFC ACCUM WFC1 F555W 1 none none none 2 551.0 S VDESJ0330-4025 2 ACS/WFC ACCUM WFC1 F555W 2 none none none 2 551.0 S VDESJ0330-4025 2 ACS/WFC ACCUM WFC1 F555W 3 none none none 2 551.0 S VDESJ0330-4025 2 ACS/WFC ACCUM WFC1 F555W 4 none none none 2 551.0 S 16756( 4) - 15-Feb-2022 17:00:18 - [ 11] Visit: 07 (ACS-WFC_imaging_J1335+3533) 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 SDSSJ1335+3 ACS/WFC ACCUM WFC1 F555W 1 530 S PATTERN 1 1 533 (2120 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 1 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 2 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 3 none none none 1 N/A SDSSJ1335+3533 1 ACS/WFC ACCUM WFC1 F555W 4 none none none 1 N/A 16756( 4) - 15-Feb-2022 17:00:18 - [ 12] Summary Form for Proposal 16756 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=10 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W, F850LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names CFHQSJ2100-1715, CFHQSJ2229+1457, PSOJ004+17, PSOJ158-14, SDSSJ1335+3533, VDESJ0330-4025 ------------------------------------------------------------------------------------------------------------------------------------