Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5379 Report Date: 18-Jul-95:17:16 Version: ********** Check-in Date: ********** 1.Proposal Title: PROBING THE LY ALPHA FOREST AT 0.5 < Z < 1.6 USING FLARING QUASARS & BL LACS ------------------------------------------------------------------------------------ 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 John Stocke 1762 USA (303) 492-1521 ------------------------------------------------------------------------------------ 7. Abstract We propose spectroscopic observations of flaring quasars and BL Lacs with the FOS + high resolution gratings to study the line density and clus- tering of Ly alpha only lines in the hitherto inaccessible redshift range 0.5 < z < 1.6. The purpose of these observations is to determine if continuity exists between the Ly alpha "forest" at Z > 2 and the local Ly alpha clouds recently discovered by HST. If continuity can be established, then detailed observations of the "local" clouds can be applied to the high-z clouds as well. Current and planned HST observa- tions do not address the Ly alpha forest in this redshift range because high-z QSOs are generally not bright enough to obtain spectra at high enough SNR to detect sufficient Ly alpha absorptions to conduct a statistical study. The virtue of our 6 targets is that while they are generally quiescent at V = 16-18, they occasionally flare to V < 15 for periods of several months making high SNR HST/FOS 1A resolution spectra (G190H and G270H) possible in a few ksecs. Past observations suggest that normal scheduling of these targets will be sufficient to observe them with HST in their Flaring state. Each of these proposed targets is being intensively monitored using several small aperture ground-based telescopes with CCD detectors so that a flare can be detected and HST observations scheduled when the source is bright. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 7.81 par: 0 10. Num targs pri: 7 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5379 PI: John Stocke Proposal Title: PROBING THE LY ALPHA FOREST AT 0.5 < Z < 1.6 USING FLARING QUASARS & BL LACS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ John Stocke 1762 USA Geoffrey Burks 1762 USA J. Blades SPACE TELESCOPE SCIENCE USA INSTITUTE Jack Burns NEW MEXICO STATE UNIVERSITY USA Bernard Mcnamara NEW MEXICO STATE UNIVERSITY USA William Neely NF/OBSERVATORY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will obtain high SNR spectra of bright BL Lacs and quasars when they flare to V < 15 for the purpose of detecting large numbers of Ly alpha only absorption clouds at 0.5 < z < 1.6. FOS spectra will be obtained through the 1/4 x 2 arcsec slits using gratings G190H and G270H. Ly alpha only and Ly alpha + metal absorption lines will be identified in a manner similar to that described in Schneider et al (1992). At an observed equivalent width limit of ~100mA (and thus a rest equivalent width limit of ~75 mA since the G270H will give slightly lower observed limits) we expect a Ly alpha line density of 40-80 per unit redshift in each of our objects observed (Bahcall et al, 1992; Hunstead 1988) so that a minimum of 2-3 objects will need to be observed before good statistics on line densities can be determined. Given the flaring history of these objects, we expect to observe 2 of them during the two year period requested for this project. If successful, we will re-propose in a subsequent cycle to observe more flaring targets of this type. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is clearly needed for this project because for the range of redshifts of the Ly alpha lines we intend to study, the wavelengths fall in the range 1800-3100A. Although IUE spectra are available for a few of these, the minimum equivalent widths of the low dispersion IUE spectra are ~ 1A; even if these quasars were observed for full shifts when they were at their absolute brightest ever observed, a minimum equivalent width of >500 mA would be obtained in a full-shift US1 with low particle background. Given the magnitude of the targets and the weakness of the Ly alpha absorption lines, this is clearly an HST project. The exposure times listed for each of these targets assumes an optical magnitude of V = 15 (excepting 0735+178 for which V = 14.5 is assumed) and a normal quasar spectrum (i.e. nearly a power law with spectral index of -0.5 or a (B-V)=+0.3). Using the standard DQE data from the FOS handbook checked by scaling to the results obtained by the Key Project team (Bahcall et al, 1992; Schneider et al, 1992), we have estimated the exposure times necessary to obtain 4.5 sigma observed equivalent width limit of 100 mA at 1800A and 150 mA at 3200A; this yields rest frame equivalent width limits of ~ 75mA across the entire spectral range observed. These exposure times are 3000 and 6000 secs for the G270H and G190H gratings through the 1/4 x 2 arcsec slit respectively. These are "worst case" numbers in that if our photometric monitoring and IUE "quick look" spectra show the source to be brighter than 15th, the equivalent width limits will be lower. Exceptions to this general rule are noted below: 1. PKS 0215+015: This source will not be observed with the G190H because there is a Ly limit system at 2400A observed by the IUE. 2. 0735+178: This source will also be observed with the G130H grating if it flares to V < 14.5 due to the high interest in its Ly limit system at z = 0.424 as presented in the cycle 3 Linsky et al proposal. This is the BL Lac in our sample which flares to the brightest apparent magnitude and can in principle yield the highest quality Ly alpha forest information of any extragalactic source excepting 3C273 and PKS 2155-304, both of which have already been oberved with HST and both of which are at substantially lower redshifts. The G130H exposure is timed to yield ~ 150mA rest equivalent width limits at wavelengths longer than 1300A where the strong Ly limit system occurs. By assuming V = 14.0 the G130H exposure time is 7200 secs. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. In order for these observations to be successful, the FOS spectra should be obtained < 2 months after STScI is notified that we have detected a flare. This requested response time is based upon the historical flaring activity of these sources (e.g. Pollock et al, 1988). Since we will continue to monitor these sources intensely with groundbased telescopes and with IUE once a flare has commenced, a slightly longer leadtime can be tolerated if the source persists in its bright state. Because weeks rather than days of response time is required for success of these observations, this is NOT a target of opportunity proposal -- normal scheduling can accommodate to the flaring timescales of these quasars and BL Lacs to ensure a successful observation. Based upon the historical flaring history of these sources, we expect to actually observe 2 of our 6 targets in the two year time fame of this proposal. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. none Page 4 ------------------------------------------------------------------------------------ 8. Additional comments or special requests. The necessity for ground-based support in this HST proposal is obvious; our photometric monitoring is essential to the success of this proposal. Due to its essential nature we will request an amount of funding each year (~ $30K) in "preparatory" funds to support this continuing effort. The ground-based monitoring also supports the approved cycle 1 HST target of opportunity observations proposed by Blades et al (P2638; "The near-UV spectrum of 0215+015"). This proposal is not overlapping with P2638 because those observations involve GHRS spectra of two very strong Ly alpha absoprtion systems discovered by Blades et al (1985) in the IUE LWP spectrum of 0215+015 the last time it flared. Finally, we again remark that several of our targets (e.g. 0215+015 is on the Key Project list) have already been accepted for observation with the FOS in proposals granted to the GTOs or to the Key Project team. However, without photometric monitoring it is most likely that these observations will find the source in its faint state so that none of the scientific goals described herein can be accomplished. We reiterate that if the scheduled observations happen to be made by chance when the source is flaring to V < 15, then we will withdraw this source from our proposal. Ground-based 1A resolution spectra will be obtained when the source is flaring to supplement the HST/FOS observations. These spectra are required to identify the metal line systems detected by Ly alpha in the UV. ------------------------------------------------------------------------------------ 9. Description of previous HST work. P2717 ("Probing the Voids") -- CYCLE 1: Stocke and Shull (6.7 hours FOS) was directed at searches for QSO metal absorption lines in voids. P2717 is not related to the current proposal. P3584 ("Probing the Voids II") -- CYCLE 2: Stocke and Shull (31 hours GHRS) is unrelated to this proposal; it is a search for Ly-alpha lines towards 4 QSOs behind galaxy voids. From our FOS observations of two AGNs during Cycle 1, we have obtained results in three areas. First, we discovered intrinsic absorption in PG 1351+64, with 3 components resolvable; this object appears to be an example of what we have called a "BAL Seyfert" which may be related to BAL QSOs. Second, we discovered Mg II satellite emission lines (displaced +/- 4000 km/s) in PG 1351+64 and perhaps also in Ton 951 that may result from the interaction of BAL outflows with the broad-line or narrow-line regions of the host galaxy. Third, we combined our data on these 2 AGNs with that of 4 other AGNs to study UV resonance absorption lines in the Galactic halo. Special attention was paid to the C IV/C II and Si IV/Si II ratios of the six lines of sight. The strong absorption in "high ions" toward 3C 273 may be more consistent with a nearby supernova remnant than with a hot halo. Measurements of detections and/or limits on absorption lines in voids is now in progress. "PG 1351+64: An Intrinsic Absorber at Low Redshift", Granados, A., Sachs, E., Shull, J. M., & Stocke, J. T., ApJ, to be submitted (June 1993). "PG 1351+64: An Intrinsic Absorber at Low Redshift", Granados, A., Sachs, E., Shull, J. M., and Stocke, J. T., in The Evolution and Environment of Galaxies, eds. D. Hollenbach, J. M. Shull, & H. A. Thronson, proc. Tetons III Conf. (July 1992). "A UV Study through the Complete Galactic Halo by the Analysis of HST-FOS Spectra of QSOs and AGNs", Burks, G. S., Bartko, F., Shull, J. M., Stocke, J. T., Sachs, E., Burbidge, E. M., Cohen, R., Junkkarinen, V., Harms, R., & Massa, D., BAAS, 24, 763 (AAS Abstract). "A UV Study through the Complete Galactic Halo by the Analysis of HST-FOS Spectra of QSOs and AGNs", Burks, G. S., Bartko, F., Shull, J. M., Stocke, J. T., Sachs, E., Burbidge, E. M., Cohen, R., Junkkarinen, V., Harms, R., & Massa, D., ApJ, submitted (April 1993). Page 5 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The Center for Astrophysics and Space Astronomy (CASA) at the University of Colorado operates computer facilities based on VAX mainframes operating with VMS, and on SUN and SPARC2 workstations operating with UNIX. For the data analysis of GHRS and FOS spectra, we will use the SUN/SPARC2 workstations, which run IRAF in a UNIX environment. Ground-based observations in support of this research also will utilize the SUN for data reductions. These computers are already in place, and NASA/HST support funds are sought to assist in ------------------------------------------------------------------------------------ 11. Address Information Name: JOHN STOCKE Category: PI Institution: 1762 Address: CAMPUS BOX 389 City: BOULDER State: CO Zip Code: 803020389 Country: USA Telephone: (303) 492-1521 Telex (or e-mail): (SPAN) HYADES::STOCKE ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5379 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 PKS0215+015 E, 316, H, 519 RA = 2H 17M 48.945S +/- 2000.0 Z=1.75 1 V=15.0 0.1S, 2 B-V=0.3 DEC = +1D 44' 49.58" +/- 0.33" ------------------------------------------------------------------------------------------------------------------------------------ 3 0735+178 E, 316, H, 519 RA = 7H 38M 07.37S +/- 0.1S, 2000.0 Z = 0.42 1 V=15.0 DEC = +17D 42' 18.7" +/- 2 B-V=0.3 0.33" ------------------------------------------------------------------------------------------------------------------------------------ 4 0846+513 E, 316, H, RA = 8H 49M 58.03S +/- 0.1S, 2000.0 Z = 1.86 1 V=15.0 519 DEC = +51D 8' 29.0" +/- 2 B-V=0.3 0.5", PLATE-ID=021E Comments: OBSERVE ALSO WITH FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ 5 B21308+326 E, 316, H, 519 RA = 13H 10M 28.683S +/- 2000.0 Z = 2.09 1 V=15.0 0.1S, 2 B-V=0.3 DEC = +32D 20' 43.35" +/- 0.33" ------------------------------------------------------------------------------------------------------------------------------------ 6 3C446 E, 316, H, RA = 22H 25M 47.031S +/- 2000.0 Z = 1.40 1 V=15.0 519 0.1S, 2 B-V=0.3 DEC = -4D 57' 1.4" +/- 0.5", PLATE-ID=02O6 ------------------------------------------------------------------------------------------------------------------------------------ 7 3C279 E, 313, H, RA = 12H 56M 11.15S +/- 2000.0 Z = 1 V=15.0 519 0.1S, 0.538 2 B-V=0.3 DEC = -05D 47' 21.7" +/- 0.5", PLATE-ID=024R ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5379 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 6 0735+178 FOS/RD ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 6.5 CYCLE 4 / 6-31 SELECT 4 OF 6-8.5 OR 15-17 OR 18-19 OR 20-22 OR 23-25 OR 26-28 OR 29-31 ------------------------------------------------------------------------------------------------------------------------------------ 6.5 0735+178 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 7 PEAK X=.172 - 8.5 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 7 0735+178 FOS/RD ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 8 0735+178 FOS/RD ACCUM 0.3 G270H 2230- 1 1020S 1 1 3200 ------------------------------------------------------------------------------------------------------------------------------------ 8.5 0735+178 FOS/BL ACCUM 0.3 G130H 1150- 3 2295S 1 1 1600 ------------------------------------------------------------------------------------------------------------------------------------ 15 3C446 FOS/RD ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 15.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 15.5 3C446 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 16 PEAK X=.172 , 17 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 16 3C446 FOS/RD ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 17 3C446 FOS/RD ACCUM 0.3 G270H 2230- 1 1020S 1 1 3200 ------------------------------------------------------------------------------------------------------------------------------------ 18 PKS0215+015 FOS/RD ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 18.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 18.5 PKS0215+015 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 19 PEAK X=.172 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5379 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 19 PKS0215+015 FOS/RD ACCUM 0.3 G270H 2230- 1 1800S 1 1 3200 ------------------------------------------------------------------------------------------------------------------------------------ 20 0846+513 FOS/RD ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 20.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 20.5 0846+513 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 21 PEAK X=.172 , 22 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 21 0846+513 FOS/RD ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 22 0846+513 FOS/RD ACCUM 0.3 G270H 2230- 1 1020S 1 1 3200 ------------------------------------------------------------------------------------------------------------------------------------ 23 B21308+326 FOS/RD ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 23.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 23.5 B21308+326 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 24 PEAK X=.172 , 25 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 24 B21308+326 FOS/RD ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 25 B21308+326 FOS/RD ACCUM 0.3 G270H 2230- 1 1020S 1 1 3200 ------------------------------------------------------------------------------------------------------------------------------------ 26 3C279 FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 26.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 26.5 3C279 FOS/BL ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 27 PEAK X=.172 -28 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 27 3C279 FOS/BL ACCUM 0.3 G130H 1150- 3 2285S 1 1 1600 ------------------------------------------------------------------------------------------------------------------------------------ 28 3C279 FOS/RD ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5379 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 29 3C279 FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR BINARY 29.5 Comments: SELECT IF TARGET FLARING ------------------------------------------------------------------------------------------------------------------------------------ 29.5 3C279 FOS/BL ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 ONBOARD ACQ FOR 30 PEAK X=.172 -31 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 30 3C279 FOS/BL ACCUM 0.3 G130H 1150- 3 2285S 1 1 1600 ------------------------------------------------------------------------------------------------------------------------------------ 31 3C279 FOS/BL ACCUM 0.3 G190H 1900 1 1980S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5379 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-X=.172 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 7.81 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 6.5; CYCLE 4 / 6-31; SELECT 4 OF 6-8.5 OR 15-17 OR 18-19 OR 20-22 OR 23-25 OR 26-28 OR 29-31 ONBOARD ACQ FOR 7 - 8.5; ONBOARD ACQ FOR 15.5; ONBOARD ACQ FOR 16, 17; ONBOARD ACQ FOR 18.5 ONBOARD ACQ FOR 19; ONBOARD ACQ FOR 20.5; ONBOARD ACQ FOR 21, 22; ONBOARD ACQ FOR 23.5; ONBOARD ACQ FOR 24, 25 ONBOARD ACQ FOR 26.5; ONBOARD ACQ FOR 27-28 ONBOARD ACQ FOR 29.5; ONBOARD ACQ FOR 30-31 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G190H G270H G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names PKS0215+015 0735+178 0846+513 B21308+326 3C446 3C279 ------------------------------------------------------------------------------------------------------------------------------------