15137( 5) - 12-Jul-2018 12:43:06 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15137 Version: 5 Check-in Time: 12-Jul-2018 12:43:06 STScI Edit Number: 3 Title Spectroscopically-Confirmed z > 6 Galaxies with Extremely Blue UV Slopes: Possible Pop III dominated targets for JWST spectroscopy ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Linhua Jiang Peking University Y CoI: Prof. Rogier A. Windhorst Arizona State University Y CoI: Dr. Seth H. Cohen Arizona State University Y CoI: Dr. Eiichi Egami University of Arizona N CoI: Prof. Xiaohui Fan University of Arizona N CoI: Dr. Kristian Finlator New Mexico State University N CoI: Dr. Matthew Mechtley Arizona State University N CoI: Prof. Daniel Schaerer Observatoire de Geneve N ------------------------------------------------------------------------------------ Abstract We propose to use HST/WFC3 to study 7 galaxies at z>6 with much bluer rest-frame UV continua than models of stellar populations and galaxy formation can accommodate. They were selected from a dedicated, large Subaru survey of bright spectroscopically-confirmed galaxies at z>6, and have extremely steep UV-slopes around beta=-3. Such slopes have never been found in low-z galaxies, nor have they been predicted by cosmological simulations. Although recent HST observations found some extreme UV-slopes in photometrically-selected galaxies at z>6, this is controversial, since it could be caused by contamination and bias in photometrically-selected samples. Our galaxies are bright (J=25-26.5 AB-mag) with secure spectroscopic redshifts, so their measurements of beta are NOT subject to these effects. They are the most promising candidates of truly extremely blue galaxies. Their uncertainties in beta are 0.3-0.5, mainly due to the short UV continuum baseline from previous HST data. We propose to add critical WFC3 near-IR images over a larger wavelength baseline to significantly improve the beta measurements by reducing uncertainties to <0.2. The new images will conclusively confirm the existence of beta = -3 galaxies at z>6. Such ultra-blue beta-values would suggest the existence of very young stellar populations with extremely low metallicity and dust content, which are possibly Pop III star dominated. Their confirmation will have significant impact on early galaxy formation, their star formation history, associated metallicity, dust, and even initial mass function. They would make very compelling targets for JWST spectroscopy. The HST/WFC3 data therefore must be completed now. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our observing strategy is straightforward (simple broad-band photometry). We will observe 7 spectroscopically confirmed galaxies at z >= 6 with 12 HST orbits covering 7 pointings. Five galaxies are in the the Subaru Deep 15137( 5) - 12-Jul-2018 12:43:06 - [ 2] Field (13h24m, 27d30m) and two are in the UKIDSS Ultra-Deep Survey field (2h18m, -5d10m). We will observe using specific WFC3-IR filters needed to complement previous observations, and provide the optimally wide wavelength baselines to measure the SED rest-frame UV slope of the target galaxies. Each pointing will be observed in a single orbit per filter and repeated for one, two, or three WFC3 bands, chosen from F105W, F125W, F140W, and F160W. The choice of filter depends on galaxy redshift and existing data. According to our existing WFC3 data, these galaxies span a magnitude range of 25.16 < J_AB < 26.66, and WFC3 is able to detect them with one-orbit integrations. The integration of each object per band will be broken into four individual exposures with sub-pixel dithering, to improve PSF and to remove bad pixels and CRs. These galaxies were chosen so that all of them can be observed within 12 HST orbits regardless of rolling angles (with fixed coordinates). We do not have any scheduling constraints or special requirements. ------------------------------------------------------------------------------------ 15137( 5) - 12-Jul-2018 12:43:06 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDF07 GALAXY, HIGH REDSHIFT RA=13H24M15.9870S +/- 0.1", J2000 J = 26.66 AB mag GALAXY DEC=+27D16'11.05" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 SDF28 GALAXY, HIGH REDSHIFT RA=13H24M42.4520S +/- 0.1", J2000 J = 25.84 AB mag GALAXY DEC=+27D24'23.35" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 SDF30 GALAXY, HIGH REDSHIFT RA=13H24M0.3010S +/- 0.1", J2000 J = 26.11 AB mag GALAXY DEC=+27D32'37.95" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 4 SDF43 GALAXY, HIGH REDSHIFT RA=13H23M53.0540S +/- 0.1", J2000 J = 26.23 AB mag GALAXY DEC=+27D16'30.75" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 5 SDF61 GALAXY, HIGH REDSHIFT RA=13H25M22.2910S +/- 0.1", J2000 J = 25.93 AB mag GALAXY DEC=+27D35'19.95" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 6 SDF63 GALAXY, HIGH REDSHIFT RA=02H18M0.8990S +/- 0.1", J2000 J = 25.16 AB mag GALAXY DEC=-05D11'37.69" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 7 SDF64 GALAXY, HIGH REDSHIFT RA=02H17M35.3370S +/- 0.1", J2000 J = 25.22 AB mag GALAXY DEC=-05D10'32.50" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 15137( 5) - 12-Jul-2018 12:43:06 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15137( 5) - 12-Jul-2018 12:43:06 - [ 5] Visit: 01 (SDF07) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF07 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF PATTERN 1 1-2 CUM (2611.753 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDF07 WFC3/IR MULTIAC IR-FIX F160W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF07 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF07 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF07 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 2 N/A CUM SDF07 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 2 N/A CUM SDF07 2 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SDF07 2 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 1 N/A CUM SDF07 2 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 2 N/A CUM SDF07 2 WFC3/IR MULTIAC IR-FIX F160W 4 none none none 2 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 6] Visit: 02 (SDF028) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF28 WFC3/IR MULTIAC IR-FIX F140W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF GS ACQ SCENARIO BASE1B3; CUM (2611.753 PATTERN 1 1-2 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDF28 WFC3/IR MULTIAC IR-FIX F160W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF28 1 WFC3/IR MULTIAC IR-FIX F140W 1 none none none 1 N/A CUM SDF28 1 WFC3/IR MULTIAC IR-FIX F140W 2 none none none 1 N/A CUM SDF28 1 WFC3/IR MULTIAC IR-FIX F140W 3 none none none 2 N/A CUM SDF28 1 WFC3/IR MULTIAC IR-FIX F140W 4 none none none 2 N/A CUM SDF28 2 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SDF28 2 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 1 N/A CUM SDF28 2 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 2 N/A CUM SDF28 2 WFC3/IR MULTIAC IR-FIX F160W 4 none none none 2 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 7] Visit: 03 (SDF030) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF30 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF PATTERN 1 1-3 CUM (2611.753 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDF30 WFC3/IR MULTIAC IR-FIX F125W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDF30 WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF30 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF30 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF30 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 2 N/A CUM SDF30 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 3 N/A CUM SDF30 2 WFC3/IR MULTIAC IR-FIX F125W 1 none none none 1 N/A CUM SDF30 2 WFC3/IR MULTIAC IR-FIX F125W 2 none none none 2 N/A CUM SDF30 2 WFC3/IR MULTIAC IR-FIX F125W 3 none none none 2 N/A CUM SDF30 2 WFC3/IR MULTIAC IR-FIX F125W 4 none none none 3 N/A CUM SDF30 3 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SDF30 3 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 2 N/A CUM SDF30 3 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 3 N/A CUM SDF30 3 WFC3/IR MULTIAC IR-FIX F160W 4 none none none 3 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 8] Visit: 04 (SDF043) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF43 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1B3; CUM (2411.751 PATTERN 1 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF43 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF43 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF43 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 1 N/A CUM SDF43 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 1 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 9] Visit: 05 (SDF061) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF61 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF GS ACQ SCENARIO BASE1B3; CUM (2611.753 PATTERN 1 1-2 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDF61 WFC3/IR MULTIAC IR-FIX F160W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF61 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF61 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF61 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 2 N/A CUM SDF61 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 2 N/A CUM SDF61 2 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SDF61 2 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 1 N/A CUM SDF61 2 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 2 N/A CUM SDF61 2 WFC3/IR MULTIAC IR-FIX F160W 4 none none none 2 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 10] Visit: 06 (SDF063) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF63 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1B3; CUM (2411.751 PATTERN 1 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF63 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF63 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF63 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 1 N/A CUM SDF63 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 1 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 11] Visit: 07 (SDF064) Visit Requirements: PCS MODE FINE; GUID TOL 0.01"; SCHED 50% 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 SDF64 WFC3/IR MULTIAC IR-FIX F105W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1B3; CUM (2411.751 PATTERN 1 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDF64 1 WFC3/IR MULTIAC IR-FIX F105W 1 none none none 1 N/A CUM SDF64 1 WFC3/IR MULTIAC IR-FIX F105W 2 none none none 1 N/A CUM SDF64 1 WFC3/IR MULTIAC IR-FIX F105W 3 none none none 1 N/A CUM SDF64 1 WFC3/IR MULTIAC IR-FIX F105W 4 none none none 1 N/A CUM 15137( 5) - 12-Jul-2018 12:43:06 - [ 12] Summary Form for Proposal 15137 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=14, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, GUID TOL 0.01", PATTERN 1 1, PATTERN 1 1-2, PATTERN 1 1-3, PCS MODE FINE, SCHED 50% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F125W, F140W, F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDF07, SDF28, SDF30, SDF43, SDF61, SDF63, SDF64 ------------------------------------------------------------------------------------------------------------------------------------