16295( 7) - 30-Aug-2021 17:17:58 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16295 Version: 7 Check-in Time: 30-Aug-2021 17:17:58 STScI Edit Number: 3 Title A Spectroscopic Redshift for the Most Luminous Galaxy Candidate at z~11 ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Yuichi Harikane University College London Y CoI: Prof. Richard S. Ellis University College London N CoI: Dr. Masami Ouchi University of Tokyo, Institute of Cosmic N Ray Research CoI: Dr. Yoshiaki Ono University of Tokyo, Institute of Cosmic N Ray Research ------------------------------------------------------------------------------------ Abstract Detailed studies of the ages and star formation histories of the most distant known galaxies promise to provide new insight into the epoch when the first sources emerged from the cosmic dark ages as well as the practicality of using JWST to search for their progenitors. Recent progress analysing the spectral energy distributions of two spectroscopically-confirmed z>9 galaxies, MACS1149_JD1and GNz-11, has been particularly informative. One surprise is the remarkable brightness of GNz-11 at z=11 which suggests that luminous sources may somehow emerge very promptly. Until now, GNz-11 has been regarded as an anomaly. Here we propose to obtain WFC3/G141 grism spectroscopy for a second luminous candidate thought to be at z~10.9, XMM3-3085 with MUV=-23.7 mag. Both sources are consistent with being drawn from the bright end of UV luminosity function at z=5-10. However, as was the case for GNz-11, without a spectroscopic redshift a low redshift interloper or a faint dwarf star cannot be excluded. A suitable spectrum for XMM3-3085 cannot be secured with ground-based instruments because of the low atmospheric transparency at the expected wavelength of its Lyman break. Confirmation of the redshift of XMM3-3085 can be economically secured with HST and would strengthen the evidence supporting the emergence of luminous galaxies at z=11, only 400 Myrs after the Big Bang. This would provide a major impetus for surveys for earlier galaxies with JWST. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to spectroscopically confirm a Lyman break at z~11 for XMM3-3085 (02:26:59.08 -05:12:17.49). We will observe this source for a total of 4 orbits at different orientations. Orientations: In the grism observations, the 4 orbit exposures will be split into two sets of 2 orbit exposures with distinct orientations >30 deg apart. We choose orientation ranges of ORIENT=58-59 and 304-309 degrees (x-axis (direction of the spectral dispersion) is aligned to PAs=13-14 and 259-264 degrees, respectively) to avoid neighboring sources within 20 arcsec. This minimizes contaminating flux from neighboring sources. 16295( 7) - 30-Aug-2021 17:17:58 - [ 2] Choice of instruments and filters: We will use the WFC/G141 grism and a JH_140 filter for direct imaging. According to the photometric redshift uncertainty, the Lyman break should lie within the wavelength range 1.3-1.6 um (at z=10.9+/-1.0), and can be captured with the instrument throughput of >~40% in this configuration. JH_140 imaging is necessary to establish a wavelength calibration for the grism observations. Visit and dither pattern: Our observation strategy is to obtain two visits of 1 orbit at two different orientations. Each visit contains two short pre-images of F140W each followed by a long G141 grism exposure. The two sets of exposures are dithered following the standard two-point dither (WFC3-IR-DITHER-BLOB), i.e., we set POS-TARG: (-1.930, -1.729) (1.930, 1.729). Depth: We have conducted simulations to evaluable the feasibility of the grism observations. Because the photometric redshift is estimated to be z=10.9+/-1.0, we constructed 1000 model galaxy spectra at z=9.9, 10.9, and 11.9 with H=23.9 mag, adding different levels of noise for a range of exposure times based on the HST ETC. We then estimated the signal to noise ratio of the UV continuum in each case. We expect to detect a z=10.9+/-1.0 Lyman break with >10sigma significance with a ~9000 sec exposure. Each grism exposure is accompanied by a 150 seconds direct image exposure in JH_140 in the same manner as undertaken by Oesch et al. (2016). With this exposure time, we can also clearly distinguish the Lyman break from spectra of interlopers. Assuming a science exposure time of 42 minutes per orbit, we require a total of 4 orbits. ------------------------------------------------------------------------------------ 16295( 7) - 30-Aug-2021 17:17:58 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 XMM3-3085 GALAXY, HIGH REDSHIFT RA=02H26M59.0800S, J2000 V = 30 +/- 1 H=23.9 ABmag GALAXY DEC=-05D12'17.49" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16295( 7) - 30-Aug-2021 17:17:58 - [ 4] Visit: 01 (Ori_67-69_1) Visit Requirements: ORIENT 67D TO 69 D 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 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=4, SAMP-SEQ=SPARS50 1 DEF POS TARG -1.930, -1.729 CUM (152.934 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG -1.930, -1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG 1.930, 1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=5, SAMP-SEQ=SPARS50 1 DEF POS TARG 1.930, 1.729 CUM (202.934 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 | ------------------------------------------------------------------------------------------------------------------------------------ XMM3-3085 1 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 XMM3-3085 2 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 3 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 4 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 16295( 7) - 30-Aug-2021 17:17:58 - [ 5] Visit: 02 (Ori_67-69_2) Visit Requirements: ORIENT 67D TO 69 D 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 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=4, SAMP-SEQ=SPARS50 1 DEF POS TARG -1.930, -1.729 CUM (152.934 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG -1.930, -1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG 1.930, 1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=5, SAMP-SEQ=SPARS50 1 DEF POS TARG 1.930, 1.729 CUM (202.934 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 | ------------------------------------------------------------------------------------------------------------------------------------ XMM3-3085 1 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 XMM3-3085 2 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 3 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 4 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 16295( 7) - 30-Aug-2021 17:17:58 - [ 6] Visit: 03 (Ori_304-309_1) Visit Requirements: ORIENT 304D TO 309 D; ORIENT 31D TO 32 D 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 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=4, SAMP-SEQ=SPARS50 1 DEF POS TARG -1.930, -1.729 CUM (152.934 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG -1.930, -1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG 1.930, 1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=5, SAMP-SEQ=SPARS50 1 DEF POS TARG 1.930, 1.729 CUM (202.934 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 | ------------------------------------------------------------------------------------------------------------------------------------ XMM3-3085 1 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 XMM3-3085 2 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 3 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 4 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 16295( 7) - 30-Aug-2021 17:17:58 - [ 7] Visit: 04 (Ori_304-309_2) Visit Requirements: ORIENT 304D TO 309 D; ORIENT 31D TO 32 D 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 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=4, SAMP-SEQ=SPARS50 1 DEF POS TARG -1.930, -1.729 CUM (152.934 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG -1.930, -1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 XMM3-3085 WFC3/IR MULTIAC GRISM1024 G141 NSAMP=12, SAMP-SEQ=SPARS100 1 DEF POS TARG 1.930, 1.729 CUM (1102.936 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 XMM3-3085 WFC3/IR MULTIAC GRISM1024 F140W NSAMP=5, SAMP-SEQ=SPARS50 1 DEF POS TARG 1.930, 1.729 CUM (202.934 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 | ------------------------------------------------------------------------------------------------------------------------------------ XMM3-3085 1 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 XMM3-3085 2 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 3 WFC3/IR MULTIAC GRISM102 G141 none none none none 1 N/A CUM 4 XMM3-3085 4 WFC3/IR MULTIAC GRISM102 F140W none none none none 1 N/A CUM 4 16295( 7) - 30-Aug-2021 17:17:58 - [ 8] Summary Form for Proposal 16295 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM1024 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12, NSAMP=4, NSAMP=5, SAMP-SEQ=SPARS100, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 304D TO 309 D, ORIENT 31D TO 32 D, ORIENT 67D TO 69 D, POS TARG -1.930, -1.729, POS TARG 1.930, 1.729 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140W, G141 ------------------------------------------------------------------------------------------------------------------------------------ Target Names XMM3-3085 ------------------------------------------------------------------------------------------------------------------------------------