Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3755c Report Date: 09-May-96:18:49 Version: ********** Check-in Date: ********** 1.Proposal Title: THE ABSORPTION CROSS-SECTIONS OF NEARBY GALAXIES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO Sub Category QUASAR ABSORPTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Chris Blades SPACE TELESCOPE SCIENCE INST ------------------------------------------------------------------------------------ 7. Abstract We wish to examine the hypothesis that low-redshift galaxies are surrounded by extended gaseous haloes and disks. Specifically, we propose using the GHRS to search for Mg II and C IV absorption lines in the haloes of low-redshift galaxies lying fortuitously in front of background quasars. We aim to reach sensitive equivalent widths limits of 60 mA and 40 mA (2 sigma) for each of the ions, and hence to infer the chemical, ionization and kinematic conditions within the absorbing gas by accurately measuring column densities, doppler parameters, and the large-scale multicomponent structure of the lines. Comparisons of the absorption in nearby galaxies with the lines seen at higher redshifts in QSO spectra should help settle the issue of how the metal-line systems originate. The recent discovery of Ly alpha absorption at very low redshift in 3C 273 with the GHRS makes our proposal timely and relevant. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 15.03 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3755c PI: Chris Blades Proposal Title: THE ABSORPTION CROSS-SECTIONS OF NEARBY GALAXIES ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Chris Blades SPACE TELESCOPE SCIENCE U.S.A. INSTITUTE David V. Bowen SPACE TELESCOPE SCIENCE U.S.A. X INSTITUTE Max Pettini ROYAL GREENWICH OBSERVATORY U.K. X ------------------------------------------------------------------------------------ 2. Scientific Justification. ------------------------------------------------------------------------------------ 3. Description of proposed observations. We have selected 5 quasars based on their small separations from foreground galaxies and on their brightness. Pairs in which the absorption line would be blended with local Galactic lines were excluded. One of these quasars (0219+428) has been observed in Cycle~1. In this case, we wish to continue the observations to realise uniform equivalent width limits. We wish to use the G270M grating to search for Mg~II at the redshift of the galaxies listed below. We have adopted a background count of 0.012~\cds\ for Detector 2 and set all the exposure times to reach a signal-to-noise of 5-7. With the resolving power of the GHRS gratings reduced to half the pre-launch values we will achieve a resolution of 10~\Ks\ with the 270M grating. A signal-to-noise of 7 at these resolutions would give an equivalent width limit of $\simeq\:60$~m\AA\ at Mg~II and resolve components within the absorption line. Our exposure times are based on the sensitivity curves in the GHRS manual. The flux is known for 2 of the objects at the wavelength of the ion we wish to observe. The anticipated count rates also depends on the variability of the quasar, but we expect variations of < +/- 2 based on the the values found by Kinney et al. No IUE spectra exist for 0318-196 (B=15.9) or 0031-707 (V=15.5). To estimate the count rate we have compared the $B$ magnitudes of QSOs with similar redshifts in Kinney et al.'s atlas with the flux at 2800~\AA ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The study of absorption by low-redshift galactic haloes in the same ions observed at higher redshifts is arguably the most important step in understanding the nature of the absorbing galaxies in the early universe. Mg~II lines can only be observed for z > 0.2 and C~IV above z > 1.2 in the optical. These are therefore only accessible at lower redshifts with the (IUE). IUE has a small aperture which permits detection of only strong ($1-2$~\AA ) lines in the brightest quasar spectra and is unsuitable for detecting lines at the equivalent width limits (0.25~\AA ) of the higher redshift absorption line surveys. The GHRS plus HST is ideal for this study. The sensitivity of the instrument is high enough to detect weak Mg~II lines in bright quasars, and, with the intermediate- dispersion gratings, data can be obtained with a resolution which discerns the large-scale velocity structure of the absorption-line profiles. This in turn permits a more accurate determination of column densities and doppler parameters, and leads to a more detailed analysis of the chemical, ionization and kinematics of the absorbing gas. For these two reasons, the GHRS is more suitable for studying the physics of galactic haloes than the FOS. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. All the data should be reducible using standard IRAF and STSDAS reduction packages. For absorption lines in which we resolve components, we have profile fitting routines available for subjective fits to the data, plus automatic routines which produce a best fit based on minimizing chi-squared. One of us (DVB) will work full time on the data reduction and analysis. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ------------------------------------------------------------------------------------ 9. Description of previous HST work. FOC: Blades is a member of the FOC IDT and is involved in several imaging programs, but these are not related to this program. 2553---``The ISM of nearby galaxies using SN as probes'' (Blades---PI). Related Program. P2638---``The Near Ultraviolet spectrum of 0215+015.'' Not directly related. P2644: ``The Environments of Starburst Galaxies'' (C. Norman---PI). Related Program. P2563:``SINS: The Supernova Intensive Study'' (Kirshner---PI). Related Program. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). ------------------------------------------------------------------------------------ 11. Address Information Name: CHRIS BLADES Category: PI Institution: SPACE TELESCOPE SCIENCE INSTITUTE Address: 3700 SAN MARTIN DRIVE City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: 301-338-4805 Telex (or e-mail): 6849101 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3755c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 0026+129 E,313,314 RA= 0H 29M 13.83S +/- 0.3", 2000.0 Z=0.142 1 B=14.6 DEC= +13D 16' 2.4" +/- 0.3" 2 F-CONT(2800) = 0.5E-14 Comments: PLATE-ID=XE465 ------------------------------------------------------------------------------------------------------------------------------------ 2 0637-752 E,313,314 RA= 06H 35M 46.764S +/- 2000.0 Z=0.656 1 B=15.75 0.6", 2 F-CONT(2810) = 3.0E-15 DEC= -75D 16' 16.72" +/- 0.6" ------------------------------------------------------------------------------------------------------------------------------------ 3 1543+489 E,313,314 RA= 15H 45M 30.3S +/- 0.6", 2000.0 Z=0.40 1 B=16.05 DEC= +48D 46' 7.9" +/- 0.6" 2 F-CONT(3000) = 3.2E-15 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3755c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 0026+129 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=3 1 9S 1 1 CYCLE 2 BRIGHT=RETURN ONBOARD ACQ FOR 2 DARK TIME ------------------------------------------------------------------------------------------------------------------------------------ 2 0026+129 HRS ACCUM 2.0 G270M 2796- COMB=FOUR 6 900S 6.1 1 1 CYCLE 2 2820 FP-SPLIT=TWO 5400S STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 0637-752 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=3 1 9S 2 1 CYCLE 2 BRIGHT=RETURN ONBOARD ACQ FOR 4 DARK TIME ------------------------------------------------------------------------------------------------------------------------------------ 4 0637-752 HRS ACCUM 2.0 G270M 2796- COMB=FOUR 14 900S 6.4 1 1 CYCLE 2 2810 FP-SPLIT=TWO 12600S STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5 1543+489 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=3 1 9S 2 1 CYCLE 2 BRIGHT=RETURN ONBOARD ACQ FOR 6 DARK TIME ------------------------------------------------------------------------------------------------------------------------------------ 6 1543+489 HRS ACCUM 2.0 G270M 3005- COMB=FOUR 25 870S 5.6 1 1 CYCLE 2 3014 FP-SPLIT=TWO 21750S STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3755c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 BRIGHT=RETURN COMB=FOUR FP-SPLIT=TWO STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 15.03 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 2; ONBOARD ACQ FOR 2; DARK TIME CYCLE 2 ONBOARD ACQ FOR 4; ONBOARD ACQ FOR 6; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names 0026+129 0637-752 1543+489 ------------------------------------------------------------------------------------------------------------------------------------