17601( 4) - 18-Jun-2024 22:49:45 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17601 Version: 4 Check-in Time: 18-Jun-2024 22:49:45 STScI Edit Number: 0 Title The first changing-multiplicity lensed quasar: a probe of sub-parsec quasar structure at Cosmic Noon ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Frederic Dux Ecole Polytechnique Federale de Lausanne Y CoI: Dr. Dominique Sluse Université de Liège N CoI: Dr. Cameron Lemon Oskar Klein Centre, Stockholm University N CoI: Prof. Frederic Courbin Ecole Polytechnique Federale de Lausanne N CoI: Prof. Timo Anguita Universidad Andres Bello N CoI: Dr. Neal J. Jackson University of Manchester N CoI: Prof. Anna Nierenberg University of California - Merced N ------------------------------------------------------------------------------------ Abstract A standard scheme for quasar structure has been built up over the last 60 years, comprising a supermassive black hole, accretion disk, torus, and broad and narrow line regions. Constraining these regions' kinematics and geometry remains difficult, particularly at high redshift, where all studies are unresolved. A recent discovery of a quadruply imaged lensed quasar has opened up an unprecedented and exciting probe of the subparsec-scale geometry of a quasar at z=2.7. The system shows 4 point sources in the optical (to 0.93 microns), yet only two point sources in recent JWST-MIRI imaging (5.6 microns), and follow-up ERIS-NIX Ks imaging (2.1 microns). This is entirely unexpected since lensing is achromatic, but could be explained by the source lying within a parsec of the region that splits the 4- and 2-image regimes. However, there are still several unanswered questions. How is the rest-frame UV of the accretion disk imaged four times, yet its optical emission is not? How can parts of the broad line region be imaged four times, yet the torus, thought to be larger, is not. High-resolution optical imaging is necessary to answer these questions: HST multi-band imaging will resolve the close optical image pair, and constrain a precise mass model from the lensed host galaxy arcs. Such a model will map the various optical quasar components back to the source at sub-parsec resolution, and fully exploit the existing JWST-MIRI, MUSE and ERIS datasets. Finally we will constrain the disappearance of the image pair to a narrow wavelength range, disambiguating several plausible explanations, e.g., an asymmetric torus, a second UV continuum source, or alternative dark matter models. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to use HST's Wide Field Camera 3 (WFC3) for deep, high-resolution imaging in the optical and near-infrared. We plan observations in three filters to provide a comprehensive view and understanding of the system. Specifically, we describe the reason for each filter below: - F475X: this band will provide the first ever view of image A, confirming our suspicion that this is a nearby merging pair. The bright Lya emission in the host galaxy 17601( 4) - 18-Jun-2024 22:49:45 - [ 2] would fall within this filter, providing an Einstein ring to constrain the lens model and map the host galaxy Lya emission, - F814W: a second optical filter where we know the images exist will allow comparison to F475X, and detect any astrometric change and thus a possible second spatially separated source of UV continuum emission. Furthermore, the host galaxy will again be lensed into a bright arc of about 21 i-mag/arcsec2 (F814W), and can be revealed with high SNR, - F160W: this filter covers a yet completely uncharted wavelength range, that of the disappearing image. If the images are seen, we can again compare the point source pair's astrometry to the optical positions and confirm the presence of any spatially separated rest-frame optical emission region. If the images are not seen, this will put strong constraints on the non-AGN continuum emitter and its position. These filter/instrument combinations match closely those of previous lensed quasar proposals (e.g., proposals 14254, 15320, and 17199), and would add to a homogeneous dataset for future studies of collections of quadruply imaged lensed quasars. Dithering pattern and exposure times: In F475X and F814W, we care about sampling the PSF as well as possible, and centroiding/separating two nearby PSFs to within milliarsecond precision. We choose to perform 4 dithers in each band, consisting of two short and two long exposures to avoid saturating the bright quasar images, with a total exposure time of 1600s. Given previous WFC3-UVIS exposure times on lensed quasars of similar brightness, such an astrometric precision can be achieved. With the WFC3/IR detector we will use a four-point dither pattern, with the standard multiple-readout sampling (MULTIACCUM mode). We will use STEP50 exposure sequences which will provide 6-8 samples in the brightest regions of the quasar images and will allow parallel buffer dumps to minimize overheads. Persistence will occur at the locations of the quasar images, and we will therefore ensure that our dithering pattern does not place our target on affected pixels. This configuration will efficiently reject cosmic rays and hot pixels, improve the sampling of the PSF of the drizzled images, and properly sample the full dynamical range of these high-contrast data. While the SNR in the arc will be 17601( 4) - 18-Jun-2024 22:49:45 - [ 3] high (up to 20 per pixel), we do not know the brightness of the close image pair (or even if they will exist at the wavelength of F160W). A total exposure time of 2200s will allow for the detection of very faint PSFs (22.2 Vega-mag, 5 sigma point source), and allow for a sufficient dynamic range to expose both the bright quasar images (B and C) and the host galaxy/faint PSF pair. ------------------------------------------------------------------------------------ 17601( 4) - 18-Jun-2024 22:49:45 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PSJ2107-1611 GALAXY, GRAVITATIONAL RA=21H07M52.4400S +/- 1.0", J2000 V = 19.5 +/- 0.5 LENS, QSO, QUASAR DEC=-16D11'32.28" +/- 1.0" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17601( 4) - 18-Jun-2024 22:49:45 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 1.56 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17601( 4) - 18-Jun-2024 22:49:45 - [ 6] 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 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=21 1 50 S (50 POS TARG 0, 0 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 2 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=6 1 375 S (375 POS TARG 0.158, 0.070 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 3 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=21 1 50 S (50 POS TARG 0.099, 0.165 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 4 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X 1 666. S POS TARG -0.060, 0.095 1 S (666 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 5 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=21 1 50 S (50 POS TARG 0, 0 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 6 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=2 1 666 S (666 POS TARG 0.158, 0.070 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 7 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=21 1 50 S (50 POS TARG 0.099, 0.165 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 8 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=9 1 355 S (355 POS TARG -0.060, 0.095 1 S S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 17601( 4) - 18-Jun-2024 22:49:45 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 9 PSJ2107-161 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=15 1 DEF PATTERN 2 9 1 CUM (1996.937 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 | ------------------------------------------------------------------------------------------------------------------------------------ PSJ2107-1611 1 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 N/A S PSJ2107-1611 2 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 N/A S PSJ2107-1611 3 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 N/A S PSJ2107-1611 4 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 N/A S PSJ2107-1611 5 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S PSJ2107-1611 6 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S PSJ2107-1611 7 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S PSJ2107-1611 8 WFC3/UVI ACCUM UVIS2 F814W none none none none 2 N/A S PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 1 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 2 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 3 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 4 none none none 2 N/A CUM 17601( 4) - 18-Jun-2024 22:49:45 - [ 8] Visit: 51 Visit Requirements: On Hold Comments: Additional Comments: Duplicate of visit 01 after gyro failure. 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 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=21 1 50 S POS TARG 0, 0 1 S see below (34 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 2 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=6 1 375 S POS TARG 0.158, 0.070 1 S see below (348 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 3 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X FLASH=21 1 50 S POS TARG 0.099, 0.165 1 S see below (34 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 4 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F475X 1 666. S POS TARG -0.060, 0.095 1 S see below (664 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 5 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=21 1 50 S POS TARG 0, 0 1 S see below (34 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 6 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=2 1 666 S POS TARG 0.158, 0.070 1 S see below (664 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 7 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=21 1 50 S POS TARG 0.099, 0.165 1 S see below (34 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 17601( 4) - 18-Jun-2024 22:49:45 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 8 PSJ2107-161 WFC3/UVI ACCUM UVIS2 F814W FLASH=9 1 355 S POS TARG -0.060, 0.095 1 S see below (435 S) Comments: https://etc.stsci.edu/etc/results/WFC3UVIS.im .1900877/ ------------------------------------------------------------------------------------------------------------------------------------ 9 PSJ2107-161 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=14 1 DEF PATTERN 2 9 1 CUM (1796.935 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 | ------------------------------------------------------------------------------------------------------------------------------------ PSJ2107-1611 1 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 34.0 S S PSJ2107-1611 2 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 348.0 S S PSJ2107-1611 3 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 34.0 S S PSJ2107-1611 4 WFC3/UVI ACCUM UVIS2 F475X none none none none 1 664.0 S S PSJ2107-1611 5 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 34.0 S S PSJ2107-1611 6 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 664.0 S S PSJ2107-1611 7 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 34.0 S S PSJ2107-1611 8 WFC3/UVI ACCUM UVIS2 F814W none none none none 2 435.0 S S PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 1 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 2 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 3 none none none 2 N/A CUM PSJ2107-1611 9 WFC3/IR MULTIAC IR F160W 4 none none none 2 N/A CUM 17601( 4) - 18-Jun-2024 22:49:45 - [ 10] Summary Form for Proposal 17601 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=2, FLASH=21, FLASH=6, FLASH=9, NSAMP=14, NSAMP=15, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 9, POS TARG -0.060, 0.095, POS TARG 0, 0, POS TARG 0.099, 0.165, POS TARG 0.158, 0.070 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F475X, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PSJ2107-1611 ------------------------------------------------------------------------------------------------------------------------------------