6717( 6) - 11/27/96 10:13 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6717 Version: 6 Check-in Date: 27-Nov-1996 09:59:32 1.Proposal Title: UV Spectroscopy of the Luminous Cooling Flow Nebula in A2597 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle GALAXIES & CLUSTERS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Christopher P. O'Dea SPACE TELESCOPE SCIENCE INSTITUTE CoI: Stefi Baum Space Telescope Science Institute N CoI: Megan Donahue Space Telescope Science Institute N CoI: Jack Gallimore Max-Planck-Institute fuer N Extraterrestrische Physik CoI: Anton Koekemoer Institut d'Astrophysique de Paris N CoI: Brian McNamara Harvard/Smithsonian Center for N Astrophysics CoI: Craig Sarazin University of Virginia N CoI: Mark Voit Space Telescope Science Institute N CoI: Mike Wise Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ 6. Abstract We propose UV spectroscopy with the FOS of the emission line nebula in the luminous cooling flow cluster Abell 2597. These observations will provide the first detection of UV lines (other than Ly-alpha\ which was detected by IUE) in the spectrum of a cooling flow nebula. This will allow us to determine line ratios (or limits) on lines which are diagnostic for (1) gas cooling from the hot ICM, (2) gas in shocks, (3) gas irradiated by the EUV and soft X-rays from cooling gas, gas in mixing layers, or shocked gas, (4) gas energized by cosmic ray heating. We will determine the source of ionization for the cooling flow nebula and investigate its relationship to the ICM and the cooling flow using our groundbased optical, ISO, ROSAT, and VLA and VLBA HI observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to obtain FOS UV spectroscopy of the emission line nebula in Abell 2597. We will cover the spectrum from 1140 to 4800 Angstrom using the G160L, G270H, and G400H gratings on the blue side. We will stay on the blue side since the blue side sensitivity is sufficient for our purposes and to avoid the overhead penalty of the side switch. The G160L and G270H give us coverage of the important diagnostic UV lines from Ly -alpha through MgII2800. The G400H exposure is only a few minutes and bridges the gap between the UV and our optical ground based spectra and allows us to match the flux scales and determine accurate ratios of optical to UV lines. In order to increase thoughput in the UV (and at the cost of spectral resolution), we are using the 1.0 arcsec aperture and the G160L grating. The loss of spectral resolution is not a problem, since even at 18.5 Angstrom resolution the majority of the diagnostic lines are unblended. Resolution of the individual line profiles is not necessary for this project. In order to optimise the spectroscopy, we include one orbit to obtain a narrow band image of OII3727 in the F410M filter which will be used as an ``Early-Acq" image to locate a large bright filament or knot in the target area of the emission line nebula. However if the McNamara Etal proposal is granted time for their narrow band image of OII, we will forgo this exposure and return that part of our allocation. Because of its huge equivalent width (270 Angstrom at the nucleus), the O II emission line will dominate the flux in this filter. At O II, the galaxy continuum is 21.4 mag/arcsec^2 and the sky background is 23.1 mag/arcsec^2. The nuclear O II surface brightness is 4.8 * 10^-15 erg s^-1 cm^-2 arcsec^-2. We predict a S/N of 10 in 9 WF pixels in about 45 minutes, or 1 orbit. Continuum subtraction will probably not be necesssary, but could be done using the U-band image of McNamara Etal (if obtained) or the F450W image from Trauger-6228 which is already in the archive. In order to detect a full range of UV diagnostic lines we need to reach a 5Sigma detection threshold of 2.0times10^-16 ergs s\\mone\\ cm\\mtwo\\ Angstrom\\mone\\ which is about one-third of H Beta. We illustrate the sensitivity of the observations for a couple critical lines. At the position of the CIV 1550 line (redshifted to 1677 Angstrom\\ in the G160L), the flux of 2.0times10^-16 ergs s^-1 cm^-2 Angstrom\\mone\\ gives a count rate of 0.014 counts/s/diode which is twice the dark count. Then, the time required to reach a signal-to-noise of 5 is 2700s. The MgII line in the G270H spectrum which is redshifted to 3027 Angstrom would produce a count rate of about 0.04 counts/s/diode and a signal-to-noise of 5 in about 10 minutes. The sensitivity of the G400H grating is similar. Adopting a 52 minute visibility for A2597, we plan to structure our orbits in the following way. First orbit: 3-stage peakup target acquisition on the galaxy nucleus. Second orbit: 6 min GS reacq, 40 min FOS/blue G160L ACCUM, 6 min overhead. Third orbit: 6 min GS reacq, 10 min G160L ACCUM, 10 min G270H ACCUM, 8 min G400H ACCUM, 18 min total overhead for the three exposures. We will repeat the exposures in orbits 2 and 3 at two off nuclear positions: one on the bright blue lobe to the northeast and the second to the north west away from the blue lobe. Thus we request 1 orbit for target acquistion and 6 orbits for spectroscopy. Real Time Justification ----------------------- None. We have obtained deep optical spectra at Palomar Observatory (Figure 2). We will also use the continuum imaging data from the cycle 6 McNamarra Etal proposal if that is approved and will use the archival F450W and F702W WFPC2 data from Trauger GTO-6228. We also plan to obtain 21cm HI observations with the VLBA to study the fine scale structure in the HI. We will combine all these data with our UV spectroscopy and ROSAT and radio continuum data to perform the definitive study of this archetypal cooling flow nebula. The currently existing radio observations (Sarazin Etal 1995) and follow on higher resolution radio observations (MERLIN) we will propose, will also provide a powerful independent constraint on the ionization of the gas. The spatial co-incidence of the radio emission with the blue lobes suggests that the radio jet has some affect on the optical appearance of the source. Our UV/optical HST line diagnostics, to be taken at three spatial locations in the source, coupled with the radio data will allow us to investigate the radio-optical continuum-emission line correlations. If shocks dominate the ionization we expect to see line ratios diagnostic of shocks where the radio jets are bright. On the other hand, in places where the radio emission is less bright, the influence of the radio source may shift to providing cosmic rays which energize the clouds - thus the emission line diagnostics may vary on and off the bright radio structure. We will look for such variations and their correlation with the radio morphology itself. We will compare the energetics of the radio lobes with the energetics required for shocks or cosmic ray ionization models, as implied by the emission -line data that we propose to obtain. We have listed A2597 as a first priority target for ISO. We will observe the fine structure lines of Si II35Mu, O I63Mu, C II158Mu and the continuum at 60, 90, 160, and 200 Mu. These data will be combined with our groundbased optical and HST UV spectroscopy to cover a wide range of diagnostic lines. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 A2597-NUC GALAXY, Elliptical, RA=23H 25M 19.73S +/- 0.2S, DEC= J2000.0 Z=0.0821 B-V = 1.08 Radio Galaxy, CLUSTER -12D 7' 26.9" +/- 1", PLATE- SURF(V) = 19.7 OF GALAXIES, Rich ID=00WQ Cluster, BCM 2 A2597-NUC- GALAXY, Elliptical, RA=23H 25M 19.735S +/- 0.05S, J2000.0 Z=0.0821 B-V = 1.08 FOS Radio Galaxy, CLUSTER DEC=-12D 7' 26.41" +/- 0.5", SURF(V) = 19.7 OF GALAXIES, Rich PLATE-ID=00WQ Cluster, BCM 3 A2597-LOBE GALAXY, Elliptical, RA=23H 25M 19.835S +/- 0.05S, J2000.0 Z=0.0821 B-V = 1.08 Radio Galaxy, CLUSTER DEC=-12D 7' 23.64" +/- 0.5", SURF(V) = 19.7 OF GALAXIES, Rich PLATE-ID=00WQ Cluster, BCM Comments: position updated sept 6 1996 4 A2597-KNOT GALAXY, Elliptical, RA=23H 25M 19.871S +/- 0.05S, J2000.0 Z=0.0821 B-V = 1.08 Radio Galaxy, CLUSTER DEC=-12D 7' 26.87" +/- 0.5", SURF(V) = 19.7 OF GALAXIES, Rich PLATE-ID=00WQ Cluster, BCM Comments: position updated sept 6 1996 5 A2597-STAR STAR RA=23H 25M 18.328S +/- 0.05S, J2000.0 Z=0.0 V-I = 2.3 DEC=-12D 7' 48.93" +/- 0.5", V = 15.0 PLATE-ID=00WQ Comments: position updated sept 6 1996 6717( 6) - 11/27/96 10:13 - [ 2] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Early Acquisition for Visit 2 Requires Early Scheduling Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 A2597-NUC WFPC2 IMAGE WF3 F410M CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 1400 S SEQ 1-3 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 A2597-NUC WFPC2 IMAGE WF3 F410M CR-SPLIT=NO 1 700 S ------------------------------------------------------------------------------------------------------------------------------------ 3 A2597-NUC WFPC2 IMAGE WF3 F410M CR-SPLIT=NO 1 100 S Comments: Short exposure to avoid saturation of offset star. ------------------------------------------------------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 3] Visit: 02 Visit Requirements: On Hold Comments: 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 A2597-STAR FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-X=3.33,SCAN-STEP-Y=1.23 1 3.0 S ONBOARD ACQuisition FOR 2 K ,SEARCH-SIZE-X=2,SEARCH-SIZE-Y=6, TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 2 A2597-STAR FOS/BL ACQ/PEA 1.0 MIRROR SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61 1 3.0 S ONBOARD ACQuisition FOR 3 K ,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, TYPE=UP Comments: need to fix exp time using magnitude from Early Acq ------------------------------------------------------------------------------------------------------------------------------------ 3 A2597-STAR FOS/BL ACQ/PEA 0.5 MIRROR SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 1 30.0 S ONBOARD ACQuisition FOR K ,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 4-15 TYPE=UP Comments: need to fix exp time using magnitude from Early Acq ------------------------------------------------------------------------------------------------------------------------------------ 4 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2200 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 8 A2597-LOBE FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2300 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 9 A2597-LOBE FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 10 A2597-LOBE FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 11 A2597-LOBE FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT R-A ------------------------------------------------------------------------------------------------------------------------------------ 12 A2597-KNOT FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2300 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 13 A2597-KNOT FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 4] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 14 A2597-KNOT FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 15 A2597-KNOT FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT R-A ------------------------------------------------------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 5] Visit: 52 Visit Requirements: On Hold Comments: Additional Comments: This is a HOPR Repeat Visit. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 A2597-STAR FOS/BL ACQ/PEA 4.3 MIRROR SCAN-STEP-X=3.33,SCAN-STEP-Y=1.23 1 3.0 S ONBOARD ACQuisition FOR 2 K ,SEARCH-SIZE-X=2,SEARCH-SIZE-Y=6, TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 2 A2597-STAR FOS/BL ACQ/PEA 1.0 MIRROR SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61 1 3.0 S ONBOARD ACQuisition FOR 3 K ,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2, TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 3 A2597-STAR FOS/BL ACQ/PEA 0.5 MIRROR SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29 1 30.0 S ONBOARD ACQuisition FOR K ,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3, 4-15 TYPE=UP ------------------------------------------------------------------------------------------------------------------------------------ 4 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2200 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 5 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 6 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 7 A2597-NUC-F FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT OS R-A ------------------------------------------------------------------------------------------------------------------------------------ 8 A2597-LOBE FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2300 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 9 A2597-LOBE FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 10 A2597-LOBE FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 11 A2597-LOBE FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT R-A ------------------------------------------------------------------------------------------------------------------------------------ 12 A2597-KNOT FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 2300 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 13 A2597-KNOT FOS/BL ACCUM 1.0-PAI G160L STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 14 A2597-KNOT FOS/BL ACCUM 1.0-PAI G270H STEP-PATT=SINGLE 1 650 S R-A ------------------------------------------------------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 15 A2597-KNOT FOS/BL ACCUM 1.0-PAI G400H STEP-PATT=SINGLE 1 550 S END ORBIT R-A ------------------------------------------------------------------------------------------------------------------------------------ 6717( 6) - 11/27/96 10:13 - [ 7] Summary Form for Proposal 6717 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.1 CR-SPLIT=NO TYPE=UP SEARCH-SIZE-Y=2 SEARCH-SIZE-Y=3 STEP-PATT=SINGLE SEARCH-SIZE-Y=6 SEARCH-SIZE-X=6 SEARCH-SIZE-X=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-3 NON-INT ONBOARD ACQuisition FOR 2 ONBOARD ACQuisition FOR 3 ONBOARD ACQuisition FOR 4-15 END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F410M MIRROR G160L G270H G400H ------------------------------------------------------------------------------------------------------------------------------------ Target Names A2597-NUC A2597-STAR A2597-NUC-FOS A2597-LOBE A2597-KNOT ------------------------------------------------------------------------------------------------------------------------------------