17437( 3) - 14-Nov-2023 15:56:51 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17437 Version: 3 Check-in Time: 14-Nov-2023 15:56:51 STScI Edit Number: 0 Title When does the initial mass function become heavy? A unique view of two massive galaxies at z=1 ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Tania Barone Swinburne University of Technology Y CoI: Dr. Sam Patrick Vaughan Macquarie University N CoI: Prof. Karl Glazebrook Swinburne University of Technology N CoI: Dr. Themiya Nanayakkara Swinburne University of Technology N CoI: Dr. Kim-Vy Tran Smithsonian Institution Astrophysical N Observatory CoI: Mr. keerthi vasan g c University of California - Davis N CoI: Prof. Evan Kirby University of Notre Dame N CoI: Nicha Leethochawalit National Astronomical Research Institute N of Thailand CoI: Ms. Zhuyun Zhuang California Institute of Technology N CoI: Prof. Tucker Jones University of California - Davis N CoI: Prof. Glenn G. Kacprzak Swinburne University of Technology N CoI: Dr. James William Nightingale Durham Univ. N CoI: Dr. Anowar J Shajib University of Chicago N CoI: Dr. Jon Trevor Mendel Australian National University N CoI: Dr. Nandini Sahu University of New South Wales Sydney N ------------------------------------------------------------------------------------ Abstract The stellar initial mass function (IMF) is a critical assumption underlying nearly every galaxy observable, yet it remains poorly constrained at high (z>0) redshift. The low-mass end in particular (M<0.4 Msun) significantly affects the mass-to-light ratio, and therefore measurements of key galaxy properties including the stellar mass and dark matter content are highly sensitive to its assumed shape. Thanks to upcoming cycle 2 JWST/NIRSpec IFU observations of 2 massive lensed quiescent galaxies at z~1, a precise measurement of the IMF at z~1 using spectral lines sensitive to low-mass stars will be possible for the first time. However, this forthcoming JWST IFU data has far more potential than solely measuring the IMF spectroscopically. This proposal will significantly expand the science available from this dataset by using only 2 orbits of HST/WFC3 to build a precise lens model of the one target without pre-existing WCF3 images and reconstruct the source galaxy's morphology. The high spatial resolution imaging from HST will open the door for spatially resolved studies of the target, allowing us to use the JWST data to its full capacity. With the combined HST imaging and JWST spectra we can then make an independent measurement of the IMF normalisation from dynamical modeling, a method which is in tension with results from stellar spectral features. Additionally, the dynamical models will provide a measure of the total mass density slope at an epoch where simulations and observations differ significantly in their predictions. This analysis will be the first of its kind and will provide a key test for galaxy 17437( 3) - 14-Nov-2023 15:56:51 - [ 2] formation and evolution theories. ------------------------------------------------------------------------------------ Observations Description ------------------------ For the IR/F140W we find that with 4 dithers of total exposure time ~900s, for an extended 3" source with 1x1 pixel binning, assuming a flat continuum in F\lambda and standard background levels we obtain a S/N ~ 10 per pixel. For the UVIS/F814W we find that in 4 frames of total exposure time ~3000s, for an extended 3" source with 2x2 pixel binning, assuming a flat continuum in F\lambda and standard background levels we obtain a S/N~ 5 per pixel. Based on the instrument overheads listed in the WFC3 user documentation, the total time required comes to 2 orbits. Increasing from 3 to 4 dithers for each filter has a negligable change on the S/N as estimated by the ETC, but will improve the spatial sampling in the dithered images. ------------------------------------------------------------------------------------ 17437( 3) - 14-Nov-2023 15:56:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AGEL0014 GALAXY, GRAVITATIONAL RA=00H14M24.2782S, J2000 V = 22.62 LENS DEC=+00D41'45.46" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17437( 3) - 14-Nov-2023 15:56:51 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BLOB Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 5.183 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.859 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 4 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BLOB Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 5.183 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.859 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 5 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17437( 3) - 14-Nov-2023 15:56:51 - [ 5] Visit: 01 (DESJ0014+0041 new sequence) Visit Requirements: On Hold Comments: Additional Comments: Sequence as decided by ETC: - For the IR/F140W 4 dithers of total exposure time 900s - For the UVIS/F814W 4 frames of total exposure time 3000s 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 AGEL0014 WFC3/IR MULTIAC IR F140W NSAMP=13, SAMP-SEQ=STEP50 1 DEF PATTERN 2 1 CUM (798.467 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AGEL0014 WFC3/UVI ACCUM UVIS2 F814W 1 803 S PATTERN 3 2 S (1606 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AGEL0014 WFC3/IR MULTIAC IR F140W NSAMP=13, SAMP-SEQ=STEP50 1 DEF POS TARG 1.4, 1.4; CUM (798.467 PATTERN 4 3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AGEL0014 WFC3/UVI ACCUM UVIS2 F814W 1 803 S POS TARG 0.3, 0.3; S (1606 S) PATTERN 5 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AGEL0014 1 WFC3/IR MULTIAC IR F140W 1 none none none 1 N/A CUM AGEL0014 1 WFC3/IR MULTIAC IR F140W 2 none none none 1 N/A CUM AGEL0014 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 N/A S AGEL0014 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 N/A S AGEL0014 3 WFC3/IR MULTIAC IR F140W 1 none none none 2 N/A CUM AGEL0014 3 WFC3/IR MULTIAC IR F140W 2 none none none 2 N/A CUM AGEL0014 4 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 2 N/A S AGEL0014 4 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 2 N/A S 17437( 3) - 14-Nov-2023 15:56:51 - [ 6] Summary Form for Proposal 17437 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 1, PATTERN 3 2, PATTERN 4 3, PATTERN 5 4, POS TARG 0.3, 0.3, POS TARG 1.4, 1.4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AGEL0014 ------------------------------------------------------------------------------------------------------------------------------------