6007( 6) - 01/31/97 15:41 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6007 Version: 6 Check-in Date: 31-Jan-1997 15:32:48 1.Proposal Title: Comparison of Large Scale Structure in QSO Absorbers and Galaxies at the Galactic Poles ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Donald G. York UNIVERSITY OF CHICAGO CoI: Chris Blades Space Telescope Science Institute N CoI: Brian Boyle University of Cambridge N CoI: Thomas Broadhurst Johns Hopkins University N CoI: Arlin Crotts Columbia University N CoI: Richard Ellis University of Cambridge N CoI: David Koo Lick Observatory N CoI: James Lauroesch University of Chicago N CoI: Adrian Melott University of Kansas N CoI: Alexander Szalay Johns Hopkins University N CoI: Chris Stoughton Fermilab N CoI: Daniel VandenBerk University of Chicago Y ------------------------------------------------------------------------------------ 6. Abstract Ly-Alpha absorbers in the spectra of QSO's are well studied at z>1.6. They have recently been detected, with HST, in unexpectedly large numbers at low redshifts. Their formation, spatial distribution, and relation to galaxies are still not understood. Whereas at high redshift they appear to be uncorrelated, at low z they show signs of clustering, albeit weaker than galaxies. Current low-z Ly-Alpha forest surveys are rather sparse and noisy, but suggest that the absorbers avoid regions of high galaxy density (e.g. Morris et al. 1993). If substantiated, this would have major consequences for our picture of structure formation in general. In this proposal we seek definitive statistical answers, with an absorber survey based upon 9 bright QSO's we have identified in fields in which we have deep, well sampled galaxy redshift surveys (North and South Galactic Poles). This low-z sample, obtainable only with HST, will provide at least an order of magnitude more absorbers in a volume with a large number of overlapping galaxy redshifts, crucial for robust estimates of the clustering. These galaxies have a sharply defined distribution of walls and voids, and even though this regularity is perhaps a statistical `accident', it enables us to perform particularly effective statistical tests to quantify the large scale spatial distribution of the absorbers by themselves and relative to the galaxies. Comparisons with the z>1.6 sample of Ly-Alpha absorbers will be particularly important for understanding evolution of both clustering and number density. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe 9 QSO's with the FOS, in a total of 45 orbits, using primarily the G190H grating. The G270H grating will also be used for several of the objects to gauge the contamination of the Ly-Alpha forest by metal line systems, and to obtain a sample of Ly-Alpha lines at higher redshift. The targets were chosen to maximize the number of close lines of sight, given the constraint of 45 orbits. We expect to obtain a total of 80 to 120 Ly-Alpha systems in our sample, in two concentrated areas of the sky, at the North and South Galactic Poles. This will enable us to construct a densely sampled volume of overlapping absorbers and galaxies with redshifts between 0 and 1. This data set will be used for various statistical analyses, to determine the spatial and physical associations among galaxies, QSO's, and the various absorbers. The necessary minimum signal to noise ratio needed for each object was calculated in order to give us an observed equivalent width threshold of W_o>0.32 Angstroms at a significance of 4.5 sigma. W=0.32 is about 1 e-folding width in the Ly-alpha equivalent width distribution at the resolution of FOS. The (1+z) expansion of equivalent widths will allow us to obtain a sample of absorbers with widths significantly less than 0.32A as well.To reach this limit requires a S/N of about 20, or about 400 counts per diode. The count rates per diode for the different gratings were calculated using the "countrate" task in the IRAF SYNPHOT package. Dividing 400 by the count rate per diode specific to each QSO, at the limiting wavelengths of 1400A, 1700A, and 2350A for the G130H, G190H, and G270H gratings respectively, gave the estimated exposure times. When available, the measured fluxs of the QSO's at the limiting useful wavelengths of the gratings were used to make the estimates. For the other objects, we used the most reliable U, B, or V magnitudes and conservatively assumed the spectra were flat. As an example, CSO179 has a U magnitude of 16.20. Assuming a flat wavelength spectrum, the "countrate" task gives 0.0494 counts/second/diode at 1700A using the G190H grating. The required exposure time is then about 8100s. At +31 degrees, after acquisitions and overheads, the first orbit has 26 minutes available for exposures, and the following have 41. Thus for this QSO, 4 are required to complete the observation. Exposure times and orbit counts were similarly calculated for each of the QSO's in our list. The final list filling 45 orbits was chosen to maximize the sensitivity to smaller scale structure, and overlap of the Ly-Alpha sample with the galaxy redshift surveys. Real Time Justification ----------------------- York will lead a ground based effort to obtain spectra of these objects at longer wavelengths. Our studies have shown that numerous heavy element lines are detected in high signal -to-noise spectra in the region redward of Ly-Alpha emission of QSO's, as expected from moderate abundance interstellar media. Use of long wavelength lines of Mg II, Fe II, Al III, and Al II, shifted into the optical region, is essential to understanding the ionization and metallicity properties of the absorbing systems, in identifying these systems with high sensitivity, and in knowing what UV absorption lines are associated with heavy element systems instead of being Ly-Alpha absorbers. Recent studies by several of us have revealed up to 20% contamination of supposed Ly-Alpha forest lines by heavy element lines, requiring deblending of the latter, or complete removal of a possible Ly-Alpha line to make a list of pure Ly-Alpha lines. Furthermore, long wavelength studies of Mg II and Fe II have revealed mistakes in previous studies. The new lists of absorbing systems that result typically show that about 20% of heavy element systems listed in the literature do not exist at all, that 20% have been misinterpreted in their ionization characteristics, and that 20% were not found in standard 3200-5000 Angstrom studies. Ellis and Koo will lead the comparison of the sample with the galaxy samples along these cones. Direct correlations with galaxies will involve another research paper. Szalay, Broadhurst, and Melott will provide simulations of the expected results for the targets acutally observed and lead the effort to determine the statistical properties of the Ly- Alpha clouds. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CT336 GALAXY, QSO RA=01H 02M 16.60S +/- 0.07S, 1950 Z=0.780 V = 17.04+/-0.3 DEC=-27D 13' 12.1" +/- 1.0" B-V = 0.25+/-0.3 2 Q0103-2622 GALAXY, QSO RA=01H 03M 34.37S +/- 0.07S, 1950 Z=0.776 V = 16.20+/-0.3 DEC=-26D 22' 23.7" +/- 1.0" B-V = 0.25+/-0.3 3 B21244+32B GALAXY, Quasar RA=12H 47M 20.79S +/- 0.07S, 2000 Z=0.949 V = 17.2+/-0.3 DEC=+32D 9' 7" +/- 1.0", PLATE- B-V = 0.25+/-0.3 ID=01PQ F(1700)=1.0+/-0.2e-15 4 CSO173 GALAXY, QSO RA=12H 50M 50.25S +/- 0.7S, 2000 Z=1.02 V = 17.0+/-0.4 DEC=+31D 25' 53.2" +/- 1", PLATE B-V = 0.25+/-0.3 -ID=01PM 5 CSO176 GALAXY, QSO RA=12H 52M 25.02S +/- 0.07S, 2000 Z=0.82 V = 17.35+/-0.2 DEC=+29D 13' 21.1" +/- 1.0", B-V = 0.25+/-0.3 PLATE-ID=01PM U = 16.75+/-0.2 B = 17.60+/-0.2 6 CSO179 GALAXY, QSO RA=12H 53M 17.52S +/- 0.07S, 2000 Z=0.78 V = 16.95+/-0.2 DEC=+31D 5' 50.4" +/- 1.0", B-V = 0.2+/-0.3 PLATE-ID=01PM U = 16.20+/-0.2 B = 17.15+/-0.2 7 TON155 GALAXY, QSO RA=13H 21M 14.66S +/- 0.07S, 2000 Z=1.703 V = 17.70+/-0.2 DEC=28D 47' 49.1" +/- 1.0", B-V = 0.20+/-0.3 PLATE-ID=009L B = 17.90+/-0.2 F(1950)=6.0+/-1.5e-16 8 TON156 GALAXY, QSO RA=13H 21M 15.8S +/- 0.07S, 2000 Z=0.549 V = 16.85+/-0.2 DEC=+28D 47' 19.6" +/- 1.0", B-V = 0.15+/-0.3 PLATE-ID=009L B = 17.00+/-0.2 F(1700)=5.0+/-2.0e-15 9 TON157 GALAXY, QSO RA=13H 23M 20.52S +/- 0.07S, 2000 Z=0.996 V = 16.83+/-0.3 DEC=+29D 10' 7.2" +/- 1.0", B-V = 0.08+/-0.3 PLATE-ID=009L F(1700)=1.25+/-0.3e-15 6007( 6) - 01/31/97 15:41 - [ 2] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CT336 FOS/RD ACQ/BIN 4.3 MIRROR 1 14.4 S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 CT336 FOS/RD ACCUM 1.0 G190H 1590-23 1 15670 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 3] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 Q0103-2622 FOS/RD ACQ/BIN 4.3 MIRROR 1 6.6 S ONBOARD ACQ FOR 2,3 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 Q0103-2622 FOS/RD ACCUM 1.0 G270H 2223-32 1 1470 S 78 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q0103-2622 FOS/RD ACCUM 1.0 G190H 1590-23 1 7110 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 4] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 B21244+32B FOS/RD ACQ/BIN 4.3 MIRROR 1 16.7 S ONBOARD ACQ FOR 2-3 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 B21244+32B FOS/RD ACCUM 1.0 G270H 2223-32 1 1470 S 78 ------------------------------------------------------------------------------------------------------------------------------------ 3 B21244+32B FOS/RD ACCUM 1.0 G190H 1590-23 1 9560 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 5] Visit: 04 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CSO173 FOS/RD ACQ/BIN 4.3 MIRROR 1 13.9 S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 CSO173 FOS/RD ACCUM 1.0 G190H 1590-23 1 15810 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 6] Visit: 05 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CSO176 FOS/RD ACQ/BIN 4.3 MIRROR 1 9.6 S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 CSO176 FOS/RD ACCUM 1.0 G190H 1590-23 1 11030 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 7] Visit: 06 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 CSO179 FOS/RD ACQ/BIN 4.3 MIRROR 1 13.3 S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 CSO179 FOS/RD ACCUM 1.0 G190H 1590-23 1 8640 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 8] Visit: 07 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 TON155 FOS/RD ACQ/BIN 4.3 MIRROR 1 26.4 S ONBOARD ACQ FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 TON155 FOS/RD ACCUM 1.0 G190H 1590-23 1 15660 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 9] Visit: 08 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 TON156 FOS/RD ACQ/BIN 4.3 MIRROR 1 12.1 S ONBOARD ACQ FOR 2-3 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 TON156 FOS/RD ACCUM 1.0 G270H 2223-32 1 1450 S 78 ------------------------------------------------------------------------------------------------------------------------------------ 3 TON156 FOS/RD ACCUM 1.0 G190H 1590-23 1 2370 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 10] Visit: 09 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 TON157 FOS/RD ACQ/BIN 4.3 MIRROR 1 11.9 S ONBOARD ACQ FOR 2-3 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 TON157 FOS/RD ACCUM 1.0 G270H 2223-32 1 1450 S 78 ------------------------------------------------------------------------------------------------------------------------------------ 3 TON157 FOS/RD ACCUM 1.0 G190H 1590-23 1 7110 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 11] Visit: 10 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 Q0103-2622 FOS/RD ACQ/BIN 4.3 MIRROR 1 6.6 S ONBOARD ACQ FOR 2,3 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 Q0103-2622 FOS/RD ACCUM 1.0 G270H 2223-32 1 1470 S 78 ------------------------------------------------------------------------------------------------------------------------------------ 3 Q0103-2622 FOS/RD ACCUM 1.0 G190H 1590-23 1 7110 S 12 ------------------------------------------------------------------------------------------------------------------------------------ 6007( 6) - 01/31/97 15:41 - [ 12] Summary Form for Proposal 6007 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 2,3 ONBOARD ACQ FOR 2-3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G190H G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names CT336 Q0103-2622 B21244+32B CSO173 CSO176 CSO179 TON155 TON156 TON157 ------------------------------------------------------------------------------------------------------------------------------------