6091( 0) - 07/18/95 19:56 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6091 Version: ********** Check-in Date: ********** 1.Proposal Title: Determining the Ionization Equilibrium and Abundances in BALQSOs ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Quasars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Nahum Arav California Institute of Technology CoI: Kirk Korista University of Kentucky Y CoI: Mitchell Begelman University of Colorado N CoI: Martijn de Kool Max-Planck Institute N ------------------------------------------------------------------------------------ 6. Abstract About 10\% of all quasars show broad absorption lines (BALs) associated with resonance lines from abundant ions. Two important issues in the study of these objects are the determination of the ionization equilibrium and the determination of the chemical abundances that give rise to the observed BALs. Ground-based spectra by themselves are of limited value here. The main problem is that only about four BALs are typically observed from the ground, and each arises from a different element. Therefore, the effects of ionization levels and abundances cannot be separated. However, UV spectroscopy with the HST combined with ground-based spectra can cover BALs from more than one ion for some elements, in particular BALs from four ions of oxygen can be observed. This situation allows us to separate the two effects and hence to improve dramatically our understanding of both. Existing HST/FOS observations can contribute toward these goals, but the targets and exposures were never chosen with attempt to obtain optimized data to answer these questions. We propose to observe an object, for which the combination of brightness, structure of the absorption trough, length of exposure and spectral coverage, will give such optimized data. We will then use a carefully planned approach to determine the ionization equilibrium and abundances from these observations. ------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 2] Observations Description ------------------------ There are about a hundred known BALQSOs. To obtain a high enough signal-to- noise spectrum with the desired rest wavelength coverage, we must choose a bright (V\ltorder 17) high redshift BALQSO (z>2). We would also like the absorption trough of the observed object (represented by the C IV Lambda1550 BAL) to be well suited for ionization studies. Two main trough shapes are desired: a) a relatively narrow (10,000 km s^-1>Delta v> 3000 km s^-1), smooth, well defined trough; b) a trough with a well resolved structure. The first shape will help us to separate most BALs, especially in crowded spectral regimes (for example, between 760 Angstrom--790 Angstrom there are at least four BALs, see Fig. 3). It will therefore make the task of determining Tau_l(v) simpler. The second shape has the potential to reveal whether the absorption components are associated with different physical flows. This can be done by checking for different Tau_l(v) changes in each of the components for BALs from different ions of the same atom. Our two final candidates represent both trough choices. 0842+3431 has the simpler trough and thus is more desirable for ionization studies. Q1524+5147 has a wider and more complicated trough, but its higher redshift shifts all the important oxygen BALs into the wavelength region of grarting G270H on FOS. This allows us to concentrate all our observing time into this one grating, which will result in a substential improvement of the signal to noise. Since none of these objects was observed below 3200 Angstrom, there is a chance that an intervening Lyman limit system will strongly absorb the spectrum below some wavelength shortward of 3200 Angstrom. In order not to waste a lot of observing time, we propose to observe each object for one orbit with the G160L (Q0842+3431) or G270H (Q1524+5147). These pilot observations will determine if there is a enough flux in these objects to justify the much longer followup observation. After examining the results of these observations, we will be able to make a better decision as to which of the two objects we want to observe with the FOS. Our request for exposure times is based on a careful comparison between the ground-based spectra of the above objects with that of 0226-1024, on the FOS spectra for this object, and on the information in the FOS Instrument Handbook. We find that all three objects have the same flux to within 30% at 3200 Angstrom. Between 3200 Angstrom-- 2200 Angstrom 0226-1024 shows a decline in flux as steep as F_Lambda\propto lambda^3. The observation taken with G190H shows that the spectrum flattens out between 2200 Angstrom- 1800 Angstrom. We can only hope that this is the worst case scenario for our objects. Therefore, based on the UV spectra of 0226-1024 and compensating for the changes due to the addition of COSTAR, we estimate that for Q0842+3431 we will need about four times the exposure used for 0226 with G270H (2000 s) and with G190H (3000 s). This is a total of 8000 s with G270H and 12000 s with G190H. According to the FOS work sheets these goals can be achieved in nine consecutive orbits. In Q1524+5147 the absorption trough is wider and more complex. Therefore, we will probably need 20,000 s -- 25,000 s of exposure with G270H in order to obtain the same scientific results. We would like to stress that all this is very uncertain due to the unknown shape of the UV continuum in these objects (we might encounter higher fluxes than in 0226). The pilot observations we are planning, would show whether the scientific goals of this program are achievable in the amount of orbits we were allocated. Real Time Justification ----------------------- The G160L pilot observations must precede the longer FOS observation, since the choice of object for the FOS observation and the exact exposures lengh will be determined on the basis of the G160L observation. none Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: *Kirk T. Korista*University of Kentucky*Dept. of Physics \& Astronomy*177 Chemistry \& Physics Bldg.*Lexington, KY 40506-0055 USA Ship Via: UPS Email: korista@pa.uky.edu , ------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 0842+3431 GALAXY, QSO RA=08H 45M 38.66S +/- 0.5S, 2000 Z = V=17.21 +/- 0.08 F-CONT(1120)= 7.0 E-16 DEC=+34D 20' 43.3" +/- 0.5", 2.131 PLATE-ID=02D5 Comments: A broad absorption line QSO. Spectral energy distribution is unknown below 3100 Angstroms observed frame. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.132 0.0 0.0 0.0 2 1524+5147 GALAXY, QSO RA=15H 25M 53.83S +/- 0.5S, 2000 Z = V=17.15 +/- 0.05 F-CONT(1110)= 6.0 E-16 DEC=+51D 36' 49.5" +/- 0.5", 2.873 PLATE-ID=01RT Comments: A broad absorption line QSO. Spectral energy distribution is unknown below 3100 Angstroms observed frame. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.207 0.0 0.0 0.0 6091( 0) - 07/18/95 19:56 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: EARLY EXPOSURE FOR VISITS 3-4 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 0842+3431 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 0842+3431 FOS/RD ACCUM 4.3 G160L 1 1520S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 6] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: EARLY EXPOSURE FOR VISITS 5-6 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 1524+5147 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 1524+5147 FOS/RD ACCUM 4.3 G270H 1 1720S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 7] Visit: 03 Visit Requirements: ON HOLD FOR 1 On Hold Comments: Waiting for results of visit 1 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 0842+3431 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2-9 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 0842+3431 FOS/RD ACCUM 4.3 G190H 1 1560S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 3 0842+3431 FOS/RD ACCUM 4.3 G190H 1 2398S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 4 0842+3431 FOS/RD ACCUM 4.3 G190H 1 2390S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 5 0842+3431 FOS/RD ACCUM 4.3 G190H 1 2390S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6 0842+3431 FOS/RD ACCUM 4.3 G190H 1 2390S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 7 0842+3431 FOS/RD ACCUM 4.3 G190H 1 2390S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 8 0842+3431 FOS/RD ACCUM 4.3 G270H 1 2310S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 9 0842+3431 FOS/RD ACCUM 4.3 G270H 1 2390S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 8] Visit: 04 Visit Requirements: ON HOLD FOR 1 On Hold Comments: Waiting for results of visit 1 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 0842+3431 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 0842+3431 FOS/RD ACCUM 4.3 G270H 1 1570S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 9] Visit: 05 Visit Requirements: ON HOLD FOR 2 On Hold Comments: Waiting for results of visit 2 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 1524+5147 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2-9 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 1524+5147 FOS/RD ACCUM 4.3 G270H 1 1720S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 3 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 4 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 5 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 7 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 8 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 9 1524+5147 FOS/RD ACCUM 4.3 G270H 1 2540S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 10] Visit: 06 Visit Requirements: ON HOLD FOR 2 On Hold Comments: Waiting for results of visit 2 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 1524+5147 FOS/RD ACQ/BIN 4.3 MIRROR 1 20S ONBOARD ACQuisition FOR 2 ARY ------------------------------------------------------------------------------------------------------------------------------------ 2 1524+5147 FOS/RD ACCUM 4.3 G270H 1 1720S EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 6091( 0) - 07/18/95 19:56 - [ 11] Summary Form for Proposal 6091 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Quasars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQuisition FOR 2 EXPAND END ORBIT ON HOLD FOR 1 ONBOARD ACQuisition FOR 2-9 ON HOLD FOR 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G160L G270H G190H ------------------------------------------------------------------------------------------------------------------------------------ Target Names 0842+3431 1524+5147 ------------------------------------------------------------------------------------------------------------------------------------