8666( 4) - 08/29/01 10:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8666 Version: 4 Check-in Date: 29-Aug-2001 10:49:18 1.Proposal Title: Outflows from the Disk Fueling the Massive Black Hole in M87 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Holland Ford The Johns Hopkins University CoI: Prof. David Axon University of Hertfordshire N CoI: Dr. Mario Livio Space Telescope Science Institute N CoI: Dr. William Sparks Space Telescope Science Institute N CoI: Dr. Zlatan Tsvetanov The Johns Hopkins University Y ------------------------------------------------------------------------------------ 5. Abstract The disk in M87 is a prototype for gas orbiting a massive central object. Although the disk is rotating, its morphology and kinematics are far from simple. A deep Halpha+N II HST image shows a trailing, three arm spiral superposed on the underlying disk, and an extended system of filaments. The NW filaments appear to connect directly to the disk. Ground- based and HST observations suggest that some of the filaments originate in a bi-directional wind emanating from the disk. Such a wind can carry away angular momentum, enabling gas to flow through the resolved disk into the accretion disk around the black hole. We propose high spatial resolution STIS spectroscopy aimed at achieving the following scientific goals: 1) Determine if winds are carrying angular momentum away from the disk, thereby enabling inflow and fueling of the massive black hole, 2) Estimation of the rate of mass loss and angular momentum loss from the disk, and 3) Use changes in the velocities and line strengths at the positions of the spiral- like features in the disk to determine if these are shocks where gas is flowing through a density wave. Because small, 100- parsec scale gaseous disks like the one in M87 are common in the centers of active galaxies, demonstration that a wind is removing angular momentum from the M87 disk will have far reaching consequences. ------------------------------------------------------------------------------------ 8666( 4) - 08/29/01 10:50 - [ 2] Observations Description ------------------------ Our proposed observations are ten contiguous 52'' * 0.2'' slit positions with grating G750M, stepped across the disk with the slit at a position angle of 343degrees. The latter is chosen so we can follow the velocities in the NW filaments as far from the disk as possible. Ten contiguous positions, which span 2'', are needed to completely cover the disk, the apparent spiral structure, and the positions where the NW filaments appear to connect to the disk. In order to improve the signal-to-noise ratio (SNR), with no loss of spectral resolution, the 0.05'' pixels will be binned 2 * 1, giving a two binned-pixel spectral resolution of 2.24 Angstrom (100 km s^-1), and a spatial relolution of 0.20'' * 0.10'' (~ 14 * 7 pc). Radial velocity accuracy will be ~ 1/3 to ~ 1/4 of the resolution, i.e. ~ 30 km s^-1. The previous FOS observations (H94 and F99) had a resolution of ~ 200 km s^-1 and a velocity accuracy of ~ 65 km s^-1. A velocity accuracy of 30 km s^-1 will be sufficient to resolve and follow outflows or infall. The resolution with the low dispersion gratings is nearly 10 times lower, and is too low to resolve all but the highest velocity features in the disk. Although the [OIII] lines and H-beta have the advantage of being unblended, they are much weaker than [NII] 6584. Consequently, we have chosen to use G750M, which includes the strong lines [OI] 6300/6360, H-alpha+[NII], and [SII] 6717/6730. The line [NII] 6584 in the FOS spectra (H94) is typically three times stronger than H-alpha, and provides a feature that can be easily measured. The emission lines in M87's disk are broad, with a FWHM of ~500 km s^-1. The STIS exposure time calculator does not easily accomodate broad emission lines and broad emission line blends. Consequently, we have chosen to scale H94's FOS observations to STIS. The STIS observations will have a smaller effective aperture and a higher dispersion, which increase the STIS exposure times. However, STIS has much higher sensitivity than FOS, which more than compensates for the smaller effective aperture and increased resolution. The photon count rate per spatial-spectra resolution element per second for an extended, broad-line emission source is C (cts/s) = pi * r^2 * Flux * Aperture_Area * Delta_lambda * System_Efficiency * lambda/hc, (1) where r is the radius of the HST primary, Flux is the monochromatic emission line flux (ergs cm^-2 s^-1 A^-1 sq-arcsec^-1), Aperture Area is the area of the effective aperture or slit in sq-arcsec, Delta_lambda is the number of angstroms across the aperture or slit, and the System Efficiency includes the HST obscuration and reflectivities. For the H94 FOS observations, Aperture area = PI * 0.13^2 sq-arcsec, Delta_lambda = 3.82 Angstrom, and System Efficiency = 0.008 (FOS Handbook, Version 4, Fig. 1.2.1 plus aperture losses). The respective quantities for STIS with the 52 * 0.2'' slit binned 2 * 1 are 0.2 * 0.1 sq-arcsec, 2.24 Angstrom, and 0.14 (STIS Handbook, Fig. 4.3). Using these quantities in the above equation, the STIS photon detection rate per 0.2'' * 0.1'' area will be ~ 4 times higher than the FOS G570H count rates through the 0.26'' aperture. This higher count rate is achived with much better spatial resolution and 3.82/2.24 = 1.7 times higher spectral resolution than the FOS observations. The emission lines [OI] 6300, H- alpha+[NII], and [SII] 6717/6730 at positions +/- 0.25'' on either side of the nucleus had good SNRs in a one orbit FOS integration. With a photon detection rate that is six times higher, a one orbit STIS spectrum at these positions will be excellent, enabling us to detect the fainter features arising from the non-circular components. The H-alpha+[NII] surface brightness in the disk falls very quickly, dropping by a factor of ~5 from r = 0.25'' to r = 0.75'' (T99a). Consequently, the spectra at r = 0.75'' will have the same quality as the previous FOS spectra at r = 0.25''. To caluclate the SNR in a STIS exposure, we use equation (1) with emission line fluxes from H94. At r = 0.25'' the fluxes in the peak of the [NII] 6584 and H-alpha lines are ~ 6.8*10^-15 and ~3.2*10^- 15 ergs cm^-2 s^-1 AA^-1 sq-arcsec^-1. Assuming a 54 minute orbit and a total overhead of ~ 15 minutes for 3 exposures, we will have three 780 second exposures per slit position. With a readout noise of 4 electrons per 2 * 1 pixel, the respective SNRs per pixel are 12.4 and 7.5. The SNRs in a 2 * 2 spatial-spectral resolution element are 25 and 15. These will give high quality spectra that show the non-circular components. At r = 0.75'', where the fluxes are ~ 5 times lower, the SNR in the peak of the [NII] 6584 emission line will be ~ 4 per pixel and ~ 8 in each 2 * 2 spatial-spectral resolution element. This will be adequate for measuring the radial velocities of non-circular components in the outer parts of the disk. Consequently, we see that we do need one orbit per slit position. Real Time Justification ----------------------- The observations should be scheduled with the slit within +/- 10deg of PA 343deg (or +/- 10degrees of PA 135deg). Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- ------------------------------------------------------------------------------------ 8666( 4) - 08/29/01 10:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4486 Galaxy, Elliptical, RA=12H 30M 49.429S +/- 0.01S, J2000 V=1280 V = 16.7 Liner DEC=12D 23' 27.985" +/- 0.01", E(B-V) = 0.01 PLATE-ID=00IY Coordinate Source: HST_IMAGE 8666( 4) - 08/29/01 10:50 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 18D TO 38D ORIENT 198D TO 218D SCHED 90% On Hold Comments: Additional Comments: Slit within +/-10d of PA343deg. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 NGC4486 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 10.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 102 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1360 S POS TARG 0, 0 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 103 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 700 S POS TARG 0,-0.2 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 104 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.2, 0 CD Comments: slit -0.2, 0 ------------------------------------------------------------------------------------------------------------------------------------ 105 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.2,-0.2 CD Comments: slit -0.2,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 106 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.4,-0.2 CD Comments: slit -0.4,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 107 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.4, 0 CD Comments: slit -0.4, 0 ------------------------------------------------------------------------------------------------------------------------------------ 108 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.6, 0 CD Comments: slit -0.6, 0 ------------------------------------------------------------------------------------------------------------------------------------ 109 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.6,-0.2 CD Comments: slit -0.6,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 110 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.8,-0.2 CD Comments: slit -0.8,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 111 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.8, 0 CD Comments: slit -0.8 ------------------------------------------------------------------------------------------------------------------------------------ 8666( 4) - 08/29/01 10:50 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 SCHED 90% On Hold Comments: Additional Comments: Slit within +/-10d of PA343deg. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 201 NGC4486 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 10.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 202 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1360 S POS TARG 0, 0 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 203 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 700 S POS TARG 0, 0.2 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 204 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG 0.2, 0 CD Comments: slit 0.2, 0 ------------------------------------------------------------------------------------------------------------------------------------ 205 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG 0.2, 0.2 CD Comments: slit 0.2, 0.2 ------------------------------------------------------------------------------------------------------------------------------------ 206 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG 0.4, 0.2 CD Comments: slit 0.4, 0.2 ------------------------------------------------------------------------------------------------------------------------------------ 207 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG 0.4, 0 CD Comments: slit 0.4, 0 ------------------------------------------------------------------------------------------------------------------------------------ 208 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG 0.6, 0 CD Comments: slit 0.6, 0 ------------------------------------------------------------------------------------------------------------------------------------ 209 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG 0.6, 0.2 CD Comments: slit 0.6, 0.2 ------------------------------------------------------------------------------------------------------------------------------------ 210 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG 0.8, 0.2 CD Comments: slit 0.8, 0.2 ------------------------------------------------------------------------------------------------------------------------------------ 211 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG 0.8, 0 CD Comments: slit 0.8, 0 ------------------------------------------------------------------------------------------------------------------------------------ 8666( 4) - 08/29/01 10:50 - [ 6] Visit: 51 Visit Priority: Visit Requirements: SCHED 90% SAME ORIENT AS 02 On Hold Comments: Additional Comments: Slit within +/-10d of PA343deg. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 NGC4486 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 10.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 102 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1360 S POS TARG 0, 0 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 103 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 700 S POS TARG 0,-0.2 CD Comments: slit through NUC ------------------------------------------------------------------------------------------------------------------------------------ 104 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.2, 0 CD Comments: slit -0.2, 0 ------------------------------------------------------------------------------------------------------------------------------------ 105 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.2,-0.2 CD Comments: slit -0.2,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 106 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.4,-0.2 CD Comments: slit -0.4,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 107 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.4, 0 CD Comments: slit -0.4, 0 ------------------------------------------------------------------------------------------------------------------------------------ 108 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.6, 0 CD Comments: slit -0.6, 0 ------------------------------------------------------------------------------------------------------------------------------------ 109 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.6,-0.2 CD Comments: slit -0.6,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 110 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=2 1 1700 S POS TARG -0.8,-0.2 CD Comments: slit -0.8,-0.2 ------------------------------------------------------------------------------------------------------------------------------------ 111 NGC4486 STIS/C ACCUM 52X0.2 G750M 6581 CR-SPLIT=NO 1 800 S POS TARG -0.8, 0 CD Comments: slit -0.8 ------------------------------------------------------------------------------------------------------------------------------------ 8666( 4) - 08/29/01 10:50 - [ 7] Summary Form for Proposal 8666 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=2 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 18D TO 38D ORIENT 198D TO 218D SCHED 90% POS TARG 0, 0 POS TARG 0,-0.2 POS TARG -0.2, 0 POS TARG -0.2,-0.2 POS TARG -0.4,-0.2 POS TARG -0.4, 0 POS TARG -0.6, 0 POS TARG -0.6,-0.2 POS TARG -0.8,-0.2 POS TARG -0.8, 0 SAME ORIENT AS 01 SCHED 90% POS TARG 0, 0.2 POS TARG 0.2, 0 POS TARG 0.2, 0.2 POS TARG 0.4, 0.2 POS TARG 0.4, 0 POS TARG 0.6, 0 POS TARG 0.6, 0.2 POS TARG 0.8, 0.2 POS TARG 0.8, 0 SCHED 90% SAME ORIENT AS 02 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4486 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6581 ------------------------------------------------------------------------------------------------------------------------------------