11183( 3) - 07/13/07 09:38 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11183 Version: 3 Check-in Time: 13-Jul-2007 13:38:11 STScI Edit Number: 1 Title Ultraviolet Imaging of Lyman-Alpha-Selected Galaxies at High Redshift ------------------------------------------------------------------------------------ Type Cycle Parallel Pointing Tolerance GO 16 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Crystal Martin University of California - Santa Barbara CoI: Dr. Alan Dressler Carnegie Institution of Washington N CoI: Dr. Patrick J. McCarthy Carnegie Institution of Washington N CoI: Prof. Marcin Sawicki St. Mary's University N ------------------------------------------------------------------------------------ Abstract We propose to carry out deep NICMOS/NIC2 imaging in the rest-frame, ultraviolet continuum of galaxies discovered in the Magellan Multi-Slit Lyman Alpha Survey. This spectroscopic survey identified ultra-faint, redshift 5.7 Lyman-alpha emitters (LAEs) in a 15 nm wide, OH-free band at 819 nm. Imaging with HST is the only way to measure their continuum intensity near rest-frame 160 nm. The ultraviolet photometry will directly measure the rate of star formation in common objects; and, when combined with groundbased Lyman-alpha luminosities, provide a reliable cross- calibration of Lyman-alpha attenuation and emission equivalent width. Direct measurement of the size of the star-forming regions, unresolved in the groundbased data, will extend measurements of the intensity of star formation to common objects in the high-redshift universe. Gaseous outflows from these galaxies are thought to be the source of their asymmetric line profiles, and area-averaged star formation rates are needed to calibrate feedback recipes, as well as eventually extend the Schmidt-Kennicutt law to high-redshift. The three targets proposed in Cycle~16 lie in fields covered by major galaxy surveys, are not as bright as the unusually luminous sources identified by such surveys at high-redshift, and present an opportunity to study properties of more common galaxies at high-redshift. ------------------------------------------------------------------------------------ 11183( 3) - 07/13/07 09:38 - [ 2] Observations Description ------------------------ Infrared-imaging of three redshift-5.7 galaxies is requested to detect their rest-frame-ultraviolet continuum emission longward of the Lyman break (at ~ 8190 A). The goal is to constrain the star formation rate using the measured UV-flux density and the size of the star-forming region. The targets are extremely faint, and detection requires the low sky background of space-based observations. The galaxies are known to be less than 0.6 arcseconds across, so NIC2 is the preferred camera. Under the warmer temperature of NCS operations, F110W imaging is slightly more sensitive to a flat continuum source than F160W. Our targets lie in one of two equatorial fields: the COSMOS field (10:00:28.6, +02:12:21.0) and a 15H field (15:23:35.48, -00:08:00.00). In two-gyro mode, the visibility of each target per orbit is 52 minutes in the absence of any additional constraints. The zodiacal background in these fields is only slightly higher than the average value used in the ETC. Nonetheless, our science exposures will be background limited. We will dither exposures by 1.54" (20.533 pixels) using the NIC-SPIRAL-DITH pattern to permit the removal of non- calibrated pixels and improve spatial sampling. A series of linearly-space, non-destructive reads will be made in MULTIACCUM readout mode and used to remove cosmic rays. The observing overheads leave 2400 s of integration time per orbit. A total integration of about 12, 000 s can be reached in one 5-orbit visit to each target. The measured hydrogen Lyman-alpha emission for our targets provide lower limits on the star formation rates between 2 and 7 solar masses per year, where the only assumptions are Case~B recombination and the slope of the stellar mass function (assumed to be Salpeter). The UV-continuum is expected to be a factor of 2 (or more) brighter than suggested by this minimum star formation rate because the blue half of the Lyman-alpha-line profile is redshifted through the line resonance by outflows and the cosmological expansion. For a star formation rate of 4 to 14 solar masses per year, the UV-continuum at 1650 A is 2.88E28 to 10.6E28 ergs/s/Hz; and the flux density at 1.1 micron is 5.4E-31 to 2.0E-30 ergs/s/cm2/Hz. The sensitivity of NIC2-F110W to such sources was estimated using the NICMOS Exposure Time Calculator. From the 12 models illustrated in Table 1 in the Phase I Proposal, we find that a spatially-unresolved star cluster is a good target; and 12, 000 s integrations in F110W will be sufficient for detection at signal-to-noise ratio of 10, or 10 - 15% accuracy for the star formation rate (with no extinction correction). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11183( 3) - 07/13/07 09:38 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL- GALAXY, HIGH REDSHIFT RA=10H00M30.4790S +/- 1.5", J2000 Z = 5.7 V = 35.0 100030+02171 GALAXY, LYMAN ALPHA DEC=+02D17'14.80" +/- 1.5" F-LINE(8190)=1+/-0.5E-17 5 CLOUD Reference Frame: ICRS 2 GAL-152258- GALAXY, HIGH REDSHIFT RA=15H22M57.8800S +/- 1.5", J2000 Z = 5.7 V = 35.0 000736 GALAXY, LYMAN ALPHA DEC=-00D07'36.34" +/- 1.5" F-LINE(8190 )=1+/-0.5E-17 CLOUD Reference Frame: ICRS 3 GAL-152409- GALAXY, LYMAN ALPHA RA=15H24M8.9290S +/- 1.5", DEC=- J2000 V = 35.0 001043 CLOUD, HIGH REDSHIFT 00D10'43.06" +/- 1.5" F-LINE=2+/-1E-17 GALAXY Reference Frame: ICRS 11183( 3) - 07/13/07 09:38 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type NIC-SPIRAL-DITH Pattern_Purpose DITHER Number_Of_Points 10 Point_Spacing 1.54 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 11183( 3) - 07/13/07 09:38 - [ 5] Visit: 01 Visit Priority: 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-100030+ NIC2 MULTIAC NIC2 F110W SAMP-SEQ=SPARS64,NSAMP=23 1 DEF GS ACQ SCENARIO BASE1TNS; 021715 CUM PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 1 none none none 1 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 2 none none none 1 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 3 none none none 2 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 4 none none none 2 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 5 none none none 3 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 6 none none none 3 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 7 none none none 4 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 8 none none none 4 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 9 none none none 5 N/A CUM GAL-100030+021715 1 NIC2 MULTIAC NIC2 F110W 10 none none none 5 N/A CUM 11183( 3) - 07/13/07 09:38 - [ 6] Visit: 02 Visit Priority: 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-152258- NIC2 MULTIAC NIC2 F110W SAMP-SEQ=SPARS64,NSAMP=23 1 DEF GS ACQ SCENARIO BASE1TNS; 000736 CUM PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 1 none none none 1 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 2 none none none 1 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 3 none none none 2 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 4 none none none 2 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 5 none none none 3 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 6 none none none 3 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 7 none none none 4 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 8 none none none 4 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 9 none none none 5 N/A CUM GAL-152258-000736 1 NIC2 MULTIAC NIC2 F110W 10 none none none 5 N/A CUM 11183( 3) - 07/13/07 09:38 - [ 7] Visit: 03 Visit Priority: 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-152409- NIC2 MULTIAC NIC2 F110W SAMP-SEQ=SPARS64,NSAMP=23 1 DEF GS ACQ SCENARIO BASE1TNS; 001043 CUM PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 1 none none none 1 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 2 none none none 1 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 3 none none none 2 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 4 none none none 2 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 5 none none none 3 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 6 none none none 3 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 7 none none none 4 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 8 none none none 4 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 9 none none none 5 N/A CUM GAL-152409-001043 1 NIC2 MULTIAC NIC2 F110W 10 none none none 5 N/A CUM 11183( 3) - 07/13/07 09:38 - [ 8] Summary Form for Proposal 11183 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=SPARS64 NSAMP=23 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1TNS; PATTERN 1 1; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-100030+021715 GAL-152258-000736 GAL-152409-001043 ------------------------------------------------------------------------------------------------------------------------------------