! $Id: 5501,v 9.1 1995/03/30 20:01:12 pepsa Exp $ coverpage: title_1: THE STRUCTURE OF THE COMA CLUSTER: A SEARCH FOR COOL, ABSORBING GAS title_2: CYCLE 4 - MEDIUM sci_cat: GALAXIES & CLUSTERS sci_subcat: CLUSTERS proposal_for: GO pi_fname: CLAUDIA pi_mi: M pi_lname: URRY pi_inst: STSCI pi_country: USA pi_phone: 410-338-4593 hours_pri: 6.00 num_pri: 1 fos: Y off_fname: ROBERT off_lname: WILLIAMS off_title: DIRECTOR off_inst: 3470 off_addr_1: 3700 SAN MARTIN DRIVE off_city: BALTIMORE off_state: MD off_zip: 21218 off_country: USA off_phone: 410-338-4710 ! end of coverpage abstract: line_1: There is tantalizing new evidence that the intracluster medium of rich line_2: clusters of galaxies is not the simple, smooth, equilibrium fluid it may line_3: at first appear to be. Spatially resolved X-ray spectroscopy indicates line_4: the presence of cool, absorbing gas distributed across a number of line_5: clusters, including the Coma cluster of galaxies, even when extensive hot line_6: gas is clearly present and cooling flows are not. Ultraviolet resonance line_7: lines are the most sensitive probes of cool gas, down to quite low column line_8: densities. We propose to search for and characterize such gas in Coma, as line_9: well as gas associated with member galaxies, by observing two background line_10: UV light sources (QSOs) at different projected radii from the cluster line_11: center. Coma is uniquely suited for this study as it is rich, extremely line_12: well-studied at many wavelengths, and, most importantly, one of the very line_13: few clusters for which bright background QSOs are are known. Assuming we line_14: detect the cool intracluster gas seen in X-rays and/or gas associated line_15: with cluster galaxies, the HST data will probe its physical state. We line_16: can further investigate its spatial dependence by observing additional line_17: background sources. The presence of cool absorbing gas has implications line_18: for the physical state of the intracluster medium, for the evolution of line_19: galactic halos in diverse environments, and for the formation of QSO line_20: absorption lines. ! ! end of abstract general_form_proposers: lname: URRY fname: CLAUDIA mi: M inst: 3470 country: USA ! lname: MUSHOTZKY fname: RICHARD mi: F inst: 2856 country: USA ! lname: DANLY fname: LAURA inst: 3470 country: USA ! lname: BRANDUARDI-RAYMONT fname: GRAZIELLA inst: 8054 country: UNITED KINGDOM esa: Y ! lname: FITCHETT fname: MICHAEL mi: J inst: 8018 country: UNITED KINGDOM esa: Y ! lname: DAVIS fname: DAVID mi: S inst: 2620 country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We propose to obtain a single FOS G130H blue spectrum of the brightest line_2: QSO from a sample of six bright QSOs known to lie behind the Coma line_3: cluster. We will acquire the target with a binary acquisition, which line_4: should work well with the COSTAR-improved PSF. Our goal is to observe line_5: Ly-alpha absorption from cool gas condensations in the intergalactic line_6: medium and/or in the halo of a nearby galaxy. The mean velocity of the line_7: Coma cluster is 6932 km/s, with a dispersion of ~1000 km/s, so that line_8: Ly-alpha from the IGM would appear at ~1244 A. The requested exposure line_9: time is that necessary to achieve a signal to noise ratio of 10 (per line_10: diode) at 1300 A, estimated using the FOS simulator with the post-COSTAR line_11: efficiencies. We assumed a V magnitude of 17.4 a power-law spectrum with line_12: index alpha=0.5, comparable to the average UV spectral index for a line_13: sample of quasars (O'Brien et al., 1988, MNRAS, 233, 801). We made no line_14: correction for interstellar extinction since the Coma cluster lies near line_15: the North Galactic Pole (bII=87 deg) and contributions from Galactic line_16: extinction should be very small. The observed column density toward the line_17: NGP from 21-cm maps is less than 1E20 cm-2 (e.g., Stark et al. 1992, line_18: ApJS, 79, 77), indicating E(B-V)<0.02, or less than 0.2 magnitudes of line_19: extinction at 1250 A (from Seaton's curves for UV extinction). The line_20: spectral region covered with the FOS G130H blue grating, 1150-1606 A, line_21: includes many species from abundant ions including HI, OI, SiII, FeII, line_22: CII, SiIV, CIV, and NV. Many of these species have several observable line_23: lines with a range of f-values. ! question: 3 section: 2 line_1: ! question: 4 section: 1 line_1: As in studies of the interstellar medium of our own galaxy, information line_2: about the structure, distribution, temperature, and density of weakly line_3: and moderately ionized gas is accessible primarily through ultraviolet line_4: spectroscopy. The targets of this proposal are too faint to have been line_5: observed previously, even at low resolution with IUE. Substantial line_6: information is available on the optical properties of the Coma cluster line_7: galaxies and on the X-ray properties of the hot gas. For the latter line_8: in particular there is new information available from long Rosat line_9: observations showing evidence of cool absorbing gas covering ~1/2 of line_10: the cluster. More sensitive X-ray observations will be made with ASCA line_11: (Astro-D), a cooperative Japanese-US moderate-to-high resolution X-ray line_12: spectroscopy experiment launched in February 1993; R. Mushotzky has line_13: access to those data as part of the ASCA science working group. In line_14: addition, the same QSOs discussed here will make excellent targets for line_15: X-ray absorption line studies with ASCA. The availability of vast line_16: amounts of complementary data from other wavelengths makes the Coma line_17: cluster a particularly desirable subject for complete study. ! question: 5 section: 1 line_1: None ! question: 6 section: 1 line_1: None ! ! question: 8 section: 1 line_1: None ! question: 9 section: 1 line_1: None by PI ! question: 10 section: 1 line_1: STScI will provide sufficient hardware and software for the data line_2: reduction and subsequent analysis. A number of science Data Analysts line_3: specifically trained in STSDAS/IRAF and the analysis of HST data are line_4: available at STScI, greatly facilitating the prompt and proper line_5: reduction of the data. ! !end of general form text general_form_address: lname: Urry fname: Claudia mi: M category: PI inst: 3470 addr_1: 3700 San Martin Drive city: Baltimore state: MD zip: 21218 country: USA phone: 410-338-4593 telex: cmu@stsci.edu ! lname: category: CON ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: QSO-1258+285 name_2: US136 descr_1: H, 519 pos_1: RA = 13H 01M 00.897S +/- 0.01S, pos_2: DEC = +28D 19' 44.21" +/- 0.1", pos_3: PLATE-ID=002K equinox: J2000 rv_or_z: Z = 1.355 fluxnum_1: 1 fluxval_1: V = 17.2 fluxnum_2: 2 fluxval_2: B-V = 0.3 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: QSO-1258+285 config: FOS/RD opmode: ACQ/PEAK aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-Y=1.204 param_2: SEARCH-SIZE-X=1 param_3: SEARCH-SIZE-Y=3 req_1: CYCLE 4 / 1-16; req_2: ONBOARD ACQ FOR 1.1 comment_1: EXPOSURE TIME DETERMINED comment_2: FROM FOS SIMULATOR. comment_3: ORDER OF RED SIDE VERSUS BLUE SIDE comment_4: NOT IMPORTANT ! linenum: 1.100 targname: QSO-1258+285 config: FOS/RD opmode: ACQ/PEAK aperture: 1.0 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-X=0.602 param_2: SCAN-STEP-Y=0.602 param_3: SEARCH-SIZE-X=6 param_4: SEARCH-SIZE-Y=2 req_1: ONBOARD ACQ FOR 1.2 ! linenum: 1.200 targname: QSO-1258+285 config: FOS/RD opmode: ACQ/PEAK aperture: 0.3 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-X=.172 param_2: SCAN-STEP-Y=.172 param_3: SEARCH-SIZE-X=5 param_4: SEARCH-SIZE-Y=5 req_1: ONBOARD ACQ FOR 1.3 ! linenum: 1.300 targname: QSO-1258+285 config: FOS/RD opmode: ACCUM aperture: 1.0 sp_element: G270H wavelength: 2223-3278 num_exp: 1 time_per_exp: 35M fluxnum_1: 1 priority: 1 ! linenum: 2.000 targname: QSO-1258+285 config: FOS/BL opmode: ACQ/PEAK aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-Y=1.204 param_2: SEARCH-SIZE-X=1 param_3: SEARCH-SIZE-Y=3 req_1: ONBOARD ACQ FOR 2.1 comment_1: EXPOSURE TIME DETERMINED comment_2: FROM FOS SIMULATOR. comment_3: ORDER OF RED SIDE VERSUS BLUE SIDE comment_4: NOT IMPORTANT ! linenum: 2.100 targname: QSO-1258+285 config: FOS/BL opmode: ACQ/PEAK aperture: 1.0 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-X=0.602 param_2: SCAN-STEP-Y=0.602 param_3: SEARCH-SIZE-X=6 param_4: SEARCH-SIZE-Y=2 req_1: ONBOARD ACQ FOR 2.2 ! linenum: 2.200 targname: QSO-1258+285 config: FOS/BL opmode: ACQ/PEAK aperture: 0.5 sp_element: MIRROR num_exp: 1 time_per_exp: 10S fluxnum_1: 1 priority: 1 param_1: SCAN-STEP-X=0.30 param_2: SCAN-STEP-Y=0.30 param_3: SEARCH-SIZE-X=3 param_4: SEARCH-SIZE-Y=3 req_1: ONBOARD ACQ FOR 3-16 ! linenum: 3.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 4.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 5.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 6.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 7.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 8.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 9.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 10.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 11.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 12.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 13.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 14.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 15.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 20M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=FOUR linenum: 16.000 targname: QSO-1258+285 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G140L wavelength: 1150-1606 num_exp: 1 time_per_exp: 10M fluxnum_1: 1 priority: 1 param_1: FP-SPLIT=TWO ! ! end of exposure logsheet ! No scan data records found