9147( 3) - 08/27/01 09:49 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9147 Version: 3 Check-in Date: 23-Feb-2001 11:26:43 1.Proposal Title: Probing the structure of the shocks in the narrow line region of M 51 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Pierre Ferruit Centre de Recherche Astronomique de Lyon CoI: Dr Yuichi Terashima University of Maryland -- Astronomy N Department CoI: Dr Mary Beth Kaiser The Johns Hopkins University N CoI: Dr Luc Binette UNAM N CoI: Mr Larry Bradley The Johns Hopkins University N CoI: Prof. Andrew S. Wilson University of Maryland -- Astronomy N Department CoI: Dr Carole G. Mundell Liverpool John Moores University -- N Astronomy Department CoI: Prof. Gerald Cecil University of N. Carolina at Chapel Hill N ------------------------------------------------------------------------------------ 5. Abstract Despite many studies, the question of whether nuclear or shock-induced photoionization dominates the gaseous ionization in the narrow-line region (NLR) of LINERs and Seyfert galaxies remains unanswered. One critical issue is the determination of the input of mechanical energy in the NLR through jet/ISM interactions. According to Bicknell et al. (1998), the latter could actually suffice to power the NLR in most Seyfert galaxies. Previous approaches to this problem have obtained integrated UV/visible line flux ratios, which are sensitive to uncertain reddening. We instead propose to exploit the high spatial resolution of HST/STIS to map several spectral lines across the shock/precursor complex in the spatially extended, jet-driven NLR of the nearby Seyfert 2 galaxy M 51. With spatial resolution of 4--5 pc (unprecedented for a galaxy jet/ISM interaction), we will map the spatial distribution of kinematic subsystems, the ionization structure, and the gaseous density, across this structure. These HST/STIS observations (probing the shock structure) will be combined with proprietary CHANDRA/ACIS data (probing the hot, shocked gas component), ground-based 3D spectroscopy (probing the more diffuse, extended structures) and radio maps. The resulting data set will be unique, and will allow us to derive quantitative measurements of the amount of mechanical energy injected in the NLR by the jet/ISM interaction. ------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 2] Observations Description ------------------------ large<~rge \star underlineSlit positions and gratings :, 2mm hspace*2mm Fig. refFigSlits shows how our four STIS long-slit spectra (52"*0arcsec2 slit, G430L and G750M gratings) would span the entire nuclear region and the brightest parts of the XNC along PA = 160 degreesr. beginfigureh begintabularlr beginminipage8.5cm \epsfxsize=8.5cm epsffilefigM51_2.eps endminipage & beginminipage7.1cm caption<~belFigSlits Sketch of the four 52"*0arcsec2 slit positions (PA = 160degreesr, solid lines) overlaid on a S/N ratio map of STIS observations of N IIwb. We have also indicated the position of the PA = 166degreesr\ slit of GTO \#7574 (dashed lines). These two maps were formed using the continuum and line surface brightness distributions inferred from the PC images, and the parameters of the G750M grating (STIS Handbook). The right hand panel is a magnified version of the nuclear regions. The calculation is detailed in section `Description of the Observations'. endminipage endtabular endfigure hspace*2mm G750M (6581) accesses the gaseous kinematics of N IIww\ at a moderate 2.24 Angstrom\ spectral resolution (4 spectral pixels, Tab. 13.34 STIS Handbook) and includes three other major lines (O Iww, H-alpha\ and the density sensitive [S II]wwb\ doublet). To enhance signal to noise ratios (S/N), the CCD will be binned by 2 pixels along the spectral direction (for the 52X0.2 slit and an extended object, this does not significantly degrade the 4 non- binned pixel-wide spectral PSF)., hspace*2mm To observe the O IIw\ and O IIIww oxygen lines, which trace changes in the ionization level, we have added for each slit position exposures with G430L (10.92 Angstrom\ resolution) to span LambdaLambda2900-5700 Angstrom. This interval also provides a large set of fainter lines (which will be detected only in the central regions after subtracting appropriate stellar templates)., beginfigureh \epsfxsize=12cm epsffilefigM51_4.eps caption<~belFigSpectra Synthetic STIS spectra of the XNC (upper spectra) and of the nuclear regions (bottom spectra). The two left spectra in each row (O IIw\ and O IIIww\ lines) correspond to 2 * 1000 s spectra with G430L (2.73 Angstrom\ per pixel), while the others (O Iww, N IIww+H-alpha\ and [S II]wwb) correspond to 4 * 1000 s spectra with G750M and 2 pixel binning in the spectral direction (1.12 Angstrom\ per binned pixel). endfigure large<~rge \star underlineExposure times : vspace*2mm We estimate exposure times in two ways. First, by constructing `S/N images' for the G750M spectra of the N IIwb\ line. From the N IIwa+H-alpha\ HST images, we have derived N IIwb\ surface brightness maps by dividing by 1.9 for the XNC and 1.5 for the nuclear regions (N II/H-alpha ratios from Tab. 7 in Ford et al. 1985). Because Cecil (1998) reports typical line widths of 150-200 kms\ for both the systemic and high-velocity components, we then spread these fluxes over 5.5 Angstrom\ (includes STIS instrumental broadening). These maps, now in units of \ergscmAarcsec, were then converted to counts (CCD\_GAIN=1) using twice (binning * 2) the sensitivity in the STIS Handbook for G750M at 6650 Angstrom\ (Tab. 13.4, 1.1 ten14 * 0.2"\ * 0.05"\ per spatial pixel) and a typical exposure of 1000 s. A corresponding `noise map' was also produced that includes photon noise from the line and continuum (using the HST F547M image) emission, dark current (2 * 2.5 ten-3 electron s^-1 per non-binned pixel) and read noise (4 electrons per binned pixel). The `count maps' were then divided by the `noise maps' to derive `S/N maps'. To achieve our scientific goals, we need to get a minimum S/N of 10 in diffuse regions of the XNC on the N IIwb\ line (allowing us to detect unambiguously other fainter lines). This yields an exposure time of 4 * 1000 s. The resulting `S/N maps' of N IIwb\ are shown in Fig. refFigSlits. Similar simulations were performed for G430L and yield exposure times of 2 * 1000 s (no binning)., However, these `S/N' maps give only an average over the line profile, so to check that the S/N was sufficient to accurately measure the N IIwb\ line profile and the [S II]\ density with G750M, or clearly detect the O IIIwb\ line with G430L, we have also simulated STIS spectra of the XNC and nuclear regions. Using the line ratios of Ford et al. (1985, Tab. 7), except for the nuclear N IIwb/O Iwa\ ratio which was from Rose & Cecil (1983), and assuming Gaussian profiles of ~200 kms\ FWHM, we have first created synthetic XNC (N IIwb\ surface brightness of 5 ten-14 \ergscmarcsec) and nuclear (N IIwb\ surface brightness of 25 ten-14 \ergscmarcsec) spectra. The resulting fluxes were then compared with the proprietary M 51 data acquired with STIS at a single slit position for the G430L and G750L wavelength regions. In mode G750L with an exposure time of 1644 seconds a signal-to-noise of 14 and 22 are obtained for the peak pixel in the brightest XNC cloudlet in the NII Lambda6548 and Lambda6584 lines respectively. The faintest XNC cloudlet that can be detected in OIII (mode G430L, 52X0.2 aperture) with a 3086 second integration has a signal-to-noise of 5, the corresponding NII emission lines have a signal-to-noise of 9 and 16. Our simulations are consistent with the signal-to-noise obtained for this data set (PI : Kaiser, GTO \#7574)., hspace*2mm Using the sensitivity curves of the two gratings and continuum levels typical of these regions (still from the F547M HST map), we derived the total counts and noise levels for each spectral pixel, for sequences of 4 (G750M) and 2 (G430L) * 1000 s exposures. A noise spectrum was then generated pixel by pixel and added to the synthetic spectrum (now in unit of counts). The resulting spectra are displayed in Fig. refFigSpectra and confirm that the S/N will be high enough for our purposes., 1mm --> Therefore, we request a total of 4 * 4000 s exposure in G750M, and 4 * 2000 s in G430L for the four slit positions. At the declination of M 51, a typical observing window is 55 minutes long. Including the overheads listed in the STIS handbook (Sect. 9), this yields a total of 3 orbits per slit position (exposures will be slightly longer than these to back into orbits), i.e. a grand total of 12 orbits. The maximum length of schedulable visits being 5 orbits, the observations will be split into 3 visits of 4 orbits each (visit 1 : G750M, two slit positions; visit 2 : G750M, two slit positions; visit 3 : G430L, four slit positions). The additional overheads induced by this splitting have been accounted for in the 12 orbits grand total. Note that the exposures will be dithered along the slit to eliminate hot pixels and cosmic ray tails. \2mm large<~rge \star underlineTarget acquisition : , 2mm The HST continuum image of M 51 (see Fig. refFigIma) shows dust through the nuclear regions, which might complicate target acquisition. However, successful positioning of the STIS slit in M 51 (actual slit was within one pixel of the intended position) was achieved in GTO \#7574 observations led by one of us (M.B. Kaiser). We will therefore use the same coordinate set and acquisition procedure as GTO \#7574 for the central slit position and apply an offset to acquire the remaining 3 slit positions., 2mm Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5194 GALAXY, SPIRAL, SEYFERT RA=13H 29M 52.77138S +/- 0.07", J2000 SURF(V) = 22.1+/-1.0e-2 DEC=47D 11' 43.040436" +/- 1", PLATE-ID=008S Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 15 NGC5194- GALAXY, SPIRAL, SEYFERT R=0.20000000000000001", PA=160D, J2000 SURF(V) = 22.1+/-1.0e-2 SHIFTED FROM 1, PLATE-ID=008S Coordinate Source: IMAGE_TIED_TO_GSC_FRAME Comments: Same as target #1 (NGC 5194) but with a shift of 0.20" (4 pixels) along the slit (PA = 160) This "dummy" target has been introduced because it was not possible to use a PATTERN with a CR-SPLIT of 2 for the first exposure and 3 for the second one. 20 NGC5194-SLIT GALAXY, SPIRAL, SEYFERT R=0.17999999999999999", PA=70D, J2000 SURF(V) = 22.1+/-1.0e-2 -EAST FROM 1, PLATE-ID=008S Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 30 NGC5194-SLIT GALAXY, SPIRAL, SEYFERT R=0.17999999999999999", PA=250D, J2000 SURF(V) = 22.1+/-1.0e-2 -WEST1 FROM 1, PLATE-ID=008S Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 40 NGC5194-SLIT GALAXY, SPIRAL, SEYFERT R=0.35999999999999999", PA=250D, J2000 SURF(V) = 22.1+/-1.0e-2 -WEST2 FROM 1, PLATE-ID=008S Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 9147( 3) - 08/27/01 09:49 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose OTHER Number_Of_Points 3 Point_Spacing 0.2 Coordinate_Frame POS-TARG Pattern_Orient 90 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 204D TO 206D ORIENT 24D TO 26D On Hold Comments: Additional Comments: The orientation of the slit must be PA = 160 +/- 1 deg (340 +/- 1 deg is also OK) Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5194 STIS/C ACQ F28X50L MIRROR ACQTYPE=DIFFUSE, 1 30 S CD P DIFFUSE-CENTER=GEOMETRIC-CENTER, CHECKBOX=33 ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5194 STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=2,BINAXIS2=1, 1 2131 S END ORBIT CD GAIN=1 Comments: CENTRAL SLIT - G750M ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5194-SHI STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=3,BINAXIS2=1, 1 2880 S END ORBIT FTED CD GAIN=1 Comments: CENTRAL SLIT - G750M - shifted along the slit ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5194-SLI STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=2,BINAXIS2=1, 1 1761 S PATTERN 1 40 EXPAND T-EAST CD GAIN=1 Comments: SLIT EAST - G750M ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5194-SLI STIS/C ACCUM 52X0.2 MIRROR CR-SPLIT=2,GAIN=1 1 30 S MAX DUR MIN DUR END ORBIT T-EAST CD Comments: Obtain a confirmation image of the final pointing for slit EAST. ------------------------------------------------------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 AFTER 01 On Hold Comments: Additional Comments: The orientation of the slit must be the same as for visit #1 (+/- 180 degrees is OK). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5194 STIS/C ACQ F28X50L MIRROR ACQTYPE=DIFFUSE, 1 30 S CD P DIFFUSE-CENTER=GEOMETRIC-CENTER, CHECKBOX=33 ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5194-SLI STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=2,BINAXIS2=1, 1 2131 S END ORBIT T-WEST1 CD GAIN=1 Comments: SLIT WEST #1 - G750M ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5194-SLI STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=3,BINAXIS2=1, 1 2880 S END ORBIT T-WEST1 CD GAIN=1 Comments: SLIT WEST #1 - G750M - NOT shifted along the slit ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5194-SLI STIS/C ACCUM 52X0.2 G750M 6581 BINAXIS1=2,CR-SPLIT=2,BINAXIS2=1, 1 1761 S PATTERN 1 40 EXPAND T-WEST2 CD GAIN=1 Comments: SLIT WEST #2 - G750M ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5194-SLI STIS/C ACCUM 52X0.2 MIRROR CR-SPLIT=2,GAIN=1 1 30 S MAX DUR MIN DUR END ORBIT T-WEST2 CD Comments: Obtain a confirmation image of the final pointing for slit WEST #2. ------------------------------------------------------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 204D TO 206D ORIENT 24D TO 26D AFTER 01 SAME ORIENT AS 01 On Hold Comments: Additional Comments: The orientation of the slit must be the same as visit 1 (+/- 180 degrees is OK). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5194 STIS/C ACQ F28X50L MIRROR ACQTYPE=DIFFUSE, 1 30 S CD P DIFFUSE-CENTER=GEOMETRIC-CENTER, CHECKBOX=33 ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5194-SLI STIS/C ACCUM 52X0.2 G430L 4300 BINAXIS1=1,CR-SPLIT=2,BINAXIS2=1, 1 2183 S EXPAND T-EAST CD GAIN=1 Comments: SLIT EAST - G430L ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5194 STIS/C ACCUM 52X0.2 G430L 4300 BINAXIS1=1,CR-SPLIT=3,BINAXIS2=1, 1 2868 S END ORBIT CD GAIN=1 Comments: CENTRAL SLIT - G430L ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5194-SLI STIS/C ACCUM 52X0.2 G430L 4300 BINAXIS1=1,CR-SPLIT=3,BINAXIS2=1, 1 2868 S END ORBIT T-WEST1 CD GAIN=1 Comments: SLIT WEST #1 - G430L ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5194-SLI STIS/C ACCUM 52X0.2 G430L 4300 BINAXIS1=1,CR-SPLIT=3,BINAXIS2=1, 1 2682 S T-WEST2 CD GAIN=1 Comments: SLIT WEST #2 - G430L ------------------------------------------------------------------------------------------------------------------------------------ 70 NGC5194-SLI STIS/C ACCUM 52X0.2 MIRROR CR-SPLIT=2,GAIN=1 1 30 S MAX DUR MIN DUR END ORBIT T-WEST2 CD Comments: Obtain a confirmation image of the final pointing for slit WEST #2. ------------------------------------------------------------------------------------------------------------------------------------ 9147( 3) - 08/27/01 09:49 - [ 8] Summary Form for Proposal 9147 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE DIFFUSE-CENTER=GEOMETRIC-CENTER CHECKBOX=33 GAIN=1 BINAXIS2=1 CR-SPLIT=2 BINAXIS1=2 CR-SPLIT=3 BINAXIS1=1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 204D TO 206D ORIENT 24D TO 26D END ORBIT PATTERN 1 40 EXPAND MAX DUR MIN DUR END ORBIT SAME ORIENT AS 01 AFTER 01 ORIENT 204D TO 206D ORIENT 24D TO 26D AFTER 01 SAME ORIENT AS 01 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M G430L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5194 NGC5194-SHIFTED NGC5194-SLIT-EAST NGC5194-SLIT-WEST1 NGC5194-SLIT-WEST2 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6581 4300 ------------------------------------------------------------------------------------------------------------------------------------