0Assigned ID: 3860
----- Attempting Submission 1 (Fri Oct 21 23:51:06 GMT 2022) -----POS TARG & PATTERN should be used carefully with ACS ramp filters as central wavelengths & transmission efficiencies vary within the apertures.Removed ORIENT constraints377671355----- Attempting Submission 1 (Thu Dec 29 00:42:59 GMT 2022) -----
----- Attempting Submission 2 (Thu Mar 16 02:06:29 GMT 2023) -----
HST Phase II Proposal 17284 successfully submitted.
Receipt: # 17284-2
----- Attempting Submission 3 (Tue Apr 04 22:37:29 GMT 2023) -----We minimize the size of the dither steps to obtain sub-pixel sampling of the PSF while minimizing the impact of wavelength and transmission variations of the ramp filter within the aperture.A young lensed quasar at cosmic dawnQSOs 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.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.
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.Sarah Bosman, Eduardo Banados, Chiara Mazzucchelli and Emanuele Farina are experts in the observations of high-redshifts quasars and are planning the ground based optical/near-IR follow up of this system.
Romain Meyer and Frederick Davies are experienced in strong lens modelling.
Fabian Walter, Romain Meyer and Roberto Decarli are experts in sub-mm observations of high-redshifts quasars, a complementary probe of the same system. Sub-mm follow-up of the same system has been submitted.Supermassive Black Holes and Active Galaxies3falsefalsefalsefalsefalsetruefalsefalseSUPPORTEDGALAXYGRAVITATIONAL LENSHIGH REDSHIFT GALAXYQUASARYESJ2000J2000z_AB=20.5mag, y_AB=20.0magACS/WFCImagingNoNoF555WACS/WFCRampFilterNoNoFR914MPOS-TARGDITHER0.334LINEfalsefalse385.29ACS-WFC-DITHER-LINE2falsePOS-TARGDITHER0.2637LINE0.1856falsefalse69.02420.7ACS-WFC-DITHER-BOX3falseThe scheduling data was generated by CASM 31.0.CASM was run in Phase II mode./private/var/folders/lb/dp07tycn66lg6vn9s48c_j6m000g04/T/OPVisit12329911633101067476.xml(Tic-Visit
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