! Proposal 6007, submission 1 ! PI: Donald G. York ! Received Wed Mar 15 16:56:56 EST 1995 ! From: devb@oddjob.uchicago.edu ! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 6007,v 6.1 1997/01/31 20:32:32 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Giselle Sleiman ! Phone: 410 338-4753 , E-mail: sleiman@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Date generated: Sun Dec 18 10:41:36 EST 1994 ! Proposal_Information ! Section 4 Title: Comparison of Large Scale Structure in QSO Absorbers and Galaxies at the Galactic Poles Proposal_Category: GO Scientific_Category: Quasars Cycle: 5 Investigators PI_name: Donald G. York PI_Institution: University of Chicago CoI_Name: Chris Blades CoI_Institution: Space Telescope Science Institute Contact: N ! Y or N (designate at most one contact) CoI_Name: Brian Boyle CoI_Institution: University of Cambridge Contact: N ! Y or N (designate at most one contact) CoI_Name: Thomas Broadhurst CoI_Institution: Johns Hopkins University Contact: N ! Y or N (designate at most one contact) CoI_Name: Arlin Crotts CoI_Institution: Columbia University Contact: N ! Y or N (designate at most one contact) CoI_Name: Richard Ellis CoI_Institution: University of Cambridge Contact: N ! Y or N (designate at most one contact) CoI_Name: David Koo CoI_Institution: Lick Observatory Contact: N ! Y or N (designate at most one contact) CoI_Name: James Lauroesch CoI_Institution: University of Chicago Contact: N ! Y or N (designate at most one contact) CoI_Name: Adrian Melott CoI_Institution: University of Kansas Contact: N ! Y or N (designate at most one contact) CoI_Name: Chris Stoughton CoI_Institution: Fermilab Contact: N ! Y or N (designate at most one contact) CoI_Name: Alexander Szalay CoI_Institution: Johns Hopkins University Contact: N ! Y or N (designate at most one contact) CoI_Name: Daniel VandenBerk CoI_Institution: University of Chicago Contact: Y ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) 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. Questions ! Free format text (please update) Observing_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: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: CT336 Alternate_Names: Q0102-2713 Description: GALAXY, QSO Position: RA=01H 02M 16.60S +/- 0.07S, DEC=-27D 13' 12.1" +/- 1.0" Equinox: 1950 RV_or_Z: Z=0.780 RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=17.04 +/- 0.3, B-V=0.25 +/- 0.3 ! Include at least V and B-V Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN