17284( 5) - 05-Apr-2023 17:35:57 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17284 Version: 5 Check-in Time: 05-Apr-2023 17:35:57 STScI Edit Number: 1 Title A young lensed quasar at cosmic dawn ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Emanuele Paolo Farina NOIRLab - Gemini North (HI) Y CoI: Eduardo Banados Max Planck Institute for Astronomy N CoI: Dr. Roberto Decarli INAF-Osservatorio di Astrofisica e Scienza N dello Spazio CoI: Dr. Thomas Connor Smithsonian Institution Astrophysical N Observatory CoI: Dr. Sarah E. I. Bosman Max Planck Institute for Astronomy N CoI: Dr. Frederick Davies Max Planck Institute for Astronomy N CoI: Dr. Fabian Walter Max Planck Institute for Astronomy N CoI: Dr. Chiara Giulia Mazzucchelli Diego Portales University N CoI: Dr. Romain Alexis Meyer Max Planck Institute for Astronomy N CoI: Prof. Xiaohui Fan University of Arizona N ------------------------------------------------------------------------------------ Abstract QSOs at z>6 are among the brightest sources in the Universe and are unparalleled tools to investigate the first billion years of Cosmic History. The origin of the first supermassive black holes, however, is an enduring mystery, since classical Eddington-limited growth has been ruled out as the formation mechanism for this population. However, to date, only the brightest end of the underlying QSO population has been investigated. New insights into the formation of the first black holes can be obtained by studying intrinsically faint QSOs that are magnified by foreground lensing galaxies. Unfortunately, while a high fraction of QSOs is predicted to be gravitationally lensed at high redshift, only one z~6 lensed QSO has been reported to date (J0439+1634 at z=6.5). Recently, the second-ever strongly-lensed QSO at z>5, PJ170+20, was discovered serendipitously. PJ170+20 is not only strongly lensed, but shows promising signs of being young, with an onset of its latest bright phase potentially only ~1000 years ago, and exhibits unusual dust emission. These characteristics open the possibility of PJ170+20 being a long-awaited keystone in QSO growth: an intrinsically faint QSO caught during (or right after) a phase of highly-obscured super-Eddington growth. We here propose exploitthe unparalleled spatial resolution allowed by ACS/WFC optical and IR imaging to confirm these properties by revealing the so far unresolved multiple lensed images and precisely pin down the location of the foreground galaxy (which are required for lens models). Unleashing PJ170+20 as unique workhorse to explore the origins of super massive black holes at cosmic dawn. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will gather ACS/WFC observations with the FR931N and F555W bands of a lensed quasar at z=6.41. We aim to obtain these data in two visits, one per filter. 17284( 5) - 05-Apr-2023 17:35:57 - [ 2] FR931N observations: Goal of this visit is to get as high resolution as possible to identify multiple quasar images. To do so, we will take observations at the shortest wavelength where the quasar emission is detectable (i.e., at the edges of the Ly-Alpha forest) using ACS/WFC with the ramp filter FR931N centered at 9100Ang. In order to balace the cosmic ray rejection and CTE correction, we choose to use 3 points line dither and not include postflash. We also made 0.334" dither steps to minimize variation in the wavelength and transmission efficiency within the aperture. F555W observations: Goal of this visit is to precisely determine the location of the foreground lensing galaxy using the intergalactic medium as a natural blocking filter to avoid the quasar light. We will observe at wavelengths shorter than the quasar's Lyman limit, i.e., with the F555W filter. We will split the observations into 4 exposures using the ACS-WFC-DITHER-BOX pattern. ------------------------------------------------------------------------------------ 17284( 5) - 05-Apr-2023 17:35:57 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PJ170+20 GALAXY, GRAVITATIONAL RA=11H23M19.8400S, J2000 z_AB=20.5mag, y_AB=20.0mag LENS, HIGH REDSHIFT DEC=+20D12'29.79" GALAXY, QUASAR Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 17284( 5) - 05-Apr-2023 17:35:57 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.334 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.29 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.2637 Line_Spacing 0.1856 Coordinate_Frame POS-TARG Pattern_Orient 20.7 Angle_Between_Sides 69.02 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17284( 5) - 05-Apr-2023 17:35:57 - [ 5] Visit: 01 (FR931N) 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 PJ170+20 ACS/WFC ACCUM WFC2-ORAM FR931N 9100 1 745 S PATTERN 2 1 P (2235 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 | ------------------------------------------------------------------------------------------------------------------------------------ PJ170+20 1 ACS/WFC ACCUM WFC2-ORA FR931N 9100 1 none none none 1 N/A MP PJ170+20 1 ACS/WFC ACCUM WFC2-ORA FR931N 9100 2 none none none 1 N/A MP PJ170+20 1 ACS/WFC ACCUM WFC2-ORA FR931N 9100 3 none none none 1 N/A MP 17284( 5) - 05-Apr-2023 17:35:57 - [ 6] Visit: 02 (F555W) 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 PJ170+20 ACS/WFC ACCUM WFC1-CTE F555W 1 520 S PATTERN 3 1 (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 | ------------------------------------------------------------------------------------------------------------------------------------ PJ170+20 1 ACS/WFC ACCUM WFC1-CTE F555W 1 none none none 1 N/A PJ170+20 1 ACS/WFC ACCUM WFC1-CTE F555W 2 none none none 1 N/A PJ170+20 1 ACS/WFC ACCUM WFC1-CTE F555W 3 none none none 1 N/A PJ170+20 1 ACS/WFC ACCUM WFC1-CTE F555W 4 none none none 1 N/A 17284( 5) - 05-Apr-2023 17:35:57 - [ 7] Summary Form for Proposal 17284 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1-CTE, WFC2-ORAMP ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 1, PATTERN 3 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W, FR931N ------------------------------------------------------------------------------------------------------------------------------------ Target Names PJ170+20 ------------------------------------------------------------------------------------------------------------------------------------