15453( 4) - 20-Mar-2018 17:36:49 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15453 Version: 4 Check-in Time: 20-Mar-2018 17:36:49 STScI Edit Number: 3 Title The Most Distant Gravitationally Lensed Quasar at z=6.5 ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Xiaohui Fan University of Arizona Y CoI: Dr. Jinyi Yang University of Arizona N CoI: Dr. Feige Wang University of California - Santa Barbara N CoI: Dr. Ian McGreer University of Arizona N CoI: Minghao Yue University of Arizona N CoI: Dr. Bram Venemans Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Xue-Bing Wu Peking University N CoI: Dr. Iskren Y. Georgiev Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Dr. Fabian Walter Max-Planck-Institut fur Astronomie, N Heidelberg ------------------------------------------------------------------------------------ Abstract We propose to use two-orbit HST/ACS imaging to confirm the highest-redshift gravitationally lensed quasar yet know at z=6.5. The lack of strongly lensed quasar at high redshift has been a long-standing puzzle. The highest redshift strongly lensed quasar known is only at z=4.8, and two large HST SNAP surveys yielded no multiply imaged quasars at z>4 among more than 200 targets. Recently, we discovered a ultra-luminous quasar at z=6.5. With M1450=-29.5, it is the most luminous known object at z>6. Close examination of the discovery spectrum shows a faint trace over the wavelength covered by strong IGM absorption, suggesting the presence of a foreground galaxy. Ground-based AO imaging with 0.2'' resolution shows that the object is marginally resolved beyond the observed PSF. A model with > 2 components produces a significantly improved fit, suggesting a compact Einstein ring size of 0.2''. The presence of a small proximity zone and the implied super-Eddington BH accretion rate further suggest that the intrinsic quasar luminosity is much lower. However, the existing ground-based images are not able to fully resolve the system. HST resolution is needed. The proposed modest ACS observations will definitely resolve the system and characterize the lensing geometry. If confirmed, this would be the first known quasar lens at reionzation epoch, providing a unique opportunity to constrain quasar lens model, measure quasar host, and probe the small scale structure of reionization-era IGM through multiple sightlines. The current visibility window for this object ends in early April. A timely observation will allow prompt publication and plan for JWST Cycle-1 followup observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ We'll perform FR782N and FR853N observations on a lensed quasar at z=6.50. Our ground based AO imaging suggests the Einstein ring is about 0.2". In order to get as high resolution possible, we will use the ramp filter FR782N centered at 15453( 4) - 20-Mar-2018 17:36:49 - [ 2] Lyman-beta emission line to detect lens images with sub-pixel dithering. In order to detect the forground lensing galaxy, we will use FR853N centered at the quasar Gunn-Peterson trough, where quasar has zero flux. In order to balace the cosmic ray rejection and CTE correction, we choose to use 3 points line dither and not include postflash for both filters. The individual exposure is 782s. ------------------------------------------------------------------------------------ 15453( 4) - 20-Mar-2018 17:36:49 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 J0439 GALAXY, GRAVITATIONAL RA=04H39M47.0980S +/- 0.2", J2000 Z = 6.5 V = 24 z_AB=19.5 LENS, HIGH REDSHIFT DEC=+16D34'15.82" +/- 0.2" GALAXY, QUASAR Reference Frame: ICRS Extended: YES Comments: This object is undetected in V-band (fainter 24 magnitude). ------------------------------------------------------------------------------------------------------------------------------------ 15453( 4) - 20-Mar-2018 17:36:49 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.170 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 47.23 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15453( 4) - 20-Mar-2018 17:36:49 - [ 5] Visit: 01 (FR782N) 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 J0439 ACS/WFC ACCUM WFC2-ORAM FR782N 7700 1 800 S GS ACQ SCENARIO SINGLE; P see below PATTERN 2 1 (2346 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 | ------------------------------------------------------------------------------------------------------------------------------------ J0439 1 ACS/WFC ACCUM WFC2-ORA FR782N 7700 1 none none none 1 782.0 S MP J0439 1 ACS/WFC ACCUM WFC2-ORA FR782N 7700 2 none none none 1 782.0 S MP J0439 1 ACS/WFC ACCUM WFC2-ORA FR782N 7700 3 none none none 1 782.0 S MP 15453( 4) - 20-Mar-2018 17:36:49 - [ 6] Visit: 02 (FR853N) 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 J0439 ACS/WFC ACCUM WFC1-IRAM FR853N 8750 1 800 S GS ACQ SCENARIO BASE1B3; P see below PATTERN 2 1 (2346 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 | ------------------------------------------------------------------------------------------------------------------------------------ J0439 1 ACS/WFC ACCUM WFC1-IRA FR853N 8750 1 none none none 1 782.0 S MP J0439 1 ACS/WFC ACCUM WFC1-IRA FR853N 8750 2 none none none 1 782.0 S MP J0439 1 ACS/WFC ACCUM WFC1-IRA FR853N 8750 3 none none none 1 782.0 S MP 15453( 4) - 20-Mar-2018 17:36:49 - [ 7] Summary Form for Proposal 15453 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1-IRAMP, WFC2-ORAMP ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, GS ACQ SCENARIO SINGLE, PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements FR782N, FR853N ------------------------------------------------------------------------------------------------------------------------------------ Target Names J0439 ------------------------------------------------------------------------------------------------------------------------------------