7862( 2) - 11/21/97 15:55 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7862 Version: 2 Check-in Date: 21-Nov-1997 15:54:00 1.Proposal Title: A Search for Near Infrared H_2 Emission in Active Elliptical Galaxies ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: LAURA FERRARESE THE JOHNS HOPKINS UNIVERSITY CoI: Holland Ford Johns Hopkins University N CoI: Walter Jaffe Leiden University N CoI: Nick Scoville California Institute of Technology N CoI: Zlatan Tsvetanov Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract We propose to use NICMOS Camera 2 to obtain narrow band H_2 v=1-0 S(1) (Lambda = 2.1218 Mum) and continuum images of three radio elliptical galaxies for which cycle 5 and cycle 6 WFPC2 images have revealed the presence of small (200 parsec) nuclear disks of dust and gas. The aim of this proposal is twofold: 1) by mapping the distribution of the molecular gas, gain further insights on the nature of the nuclear dust disks that lurk in the cores of ~ 30\ ellipticals, and 2) by looking for unresolved H_2 emission at the nuclear location, search for direct evidence of the presence of a parsec scale dusty torus in radio ellipticals: the torus is hypothesized to surround the central hot accretion disk and massive black hole, and although its presence is critical for the unification models of AGNs, direct evidence of its existence is available only for Seyferts, but not for radio ellipticals. Six orbits for each galaxy will allow us to detect emission line features with a surface brightness of 10^-16$ erg cm^-2 s^-1 arcsec^-2 and a S/N of 7 in the continuum subtracted emission line images. An additional orbit per galaxy will be spent to obtain broad band J, H and K images. ------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 2] Observations Description ------------------------ All observations will be carried out with NICMOS Camera 2. The redshifted H_2 v=1-0 S(1) (Lambda = 2.1218 Mum) emission will be centered on the F215N filter for 3C 278 (z = 4340 km s^-1), and on the F216N filter for NGC 6251 and 3C 264 (z = 7400 km s^-1 and z = 6230 km s^-1 respectively). In order to minimize thermal background variations between the on-band and the off-band images we will use the F212N filter to determine the continuum (this is the closest filter, in wavelength, to the on-band filter and is not contaminated by any other emission line). In order to correct for noisy and dead pixels all images will be dithered. To allow for optimal PSF sampling within a pixel, the dither size is chosen to be 15.5 pixels (1.1625 arcsec). No sky background is requested for the narrow band nor J (F110W) and H (F160W) broad band images, while a sky image will be obtained in the K (F205W) band. The "chop-size" and orientation of the sky region with respect to the target is chosen from available WFPC2 images to correspond to a blank part of the sky. We estimate that six orbits per galaxy, including overhead, are necessary to detect emission line regions with flux 10^-16 erg cm^-2 s^-1 arcsec^-2 with a signal to noise of 7 in the continuum subtracted (pure emission) image. Please note that the quoted flux is on the conservative side: the H_2 flux of 10^-16 erg cm^-2 s^-1 detected by Jaffe (1998) in NGC 4261 is the total flux detected in the line, within 1 arcsec, and the H_2 distribution, even if resolved, will probably tend to be clumpy. The following is an example of the exposure time estimate for NGC 6251, and is indicative of the other two galaxies. The K surface brightness in the center 2 arcsec is 13 mag arcsec^-2, or ~ 4 * 10^-3 Jy arcsec^-2. From the exposure time calculator, extended emission with flux 10^-16 erg cm^-2 s^-1 arcsec^-2 will produce a count rate 15 times smaller than expected from the underlying continuum source. Since the on-band and off-band filters have similar sensitivity and FWHM, the S/N ratio in the two filters will be comparable at the same exposure time. Therefore, to achieve a S/N of 7 in the continuum subtracted (on-band - off -band) image, we need to obtain a S/N of 15 * 7 * 2^0.5 ~ 150 in both filters. According to the exposure time simulator, this can be achieved in 9000 seconds integration in each filter. After subtracting overhead, the visibility window for the target is about 50 minutes each orbit, therefore a total of 6 orbit (three for the on-band image and three for the off -band) are necessary. In addition to the narrow band on and off-line images, we plan to obtain broad band images in F110W, F160W and F222M. Given the high K surface brightness of the proposed targets, 15 minutes integration per filter per galaxy will reach a S/N of over 700 in the center. Therefore, one extra orbit per galaxy will be enough to obtain images in all three filters. In conclusion, we ask for a total of (6+1)*3 = 21 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6251 GALAXY,Elliptical,Radio RA=16H 32M 32.104S+/- J2000 V=+7400 SURF(V) = 19.5+/-1.0 Galaxy 0.03S,DEC=+82D 32' 16.67"+/-0.5" SURF(I) = 18.1+/-1.0 Comments: Coordinates calculated from WFPC2 u3fm0107t jitter file 2 3C264 GALAXY,Elliptical,Radio RA=11H 45M 04.956S+/- J2000 V=+6470 SURF(V) = 20.0+/-1.0 Galaxy,Interacting 0.03S,DEC=+19D 36' 23.22"+/-0.5" SURF(I) = 18.5+/-1.0 Galaxy Comments: Coordinates calculated from WFPC2 u34q0401t jitter file 3 3C278 GALAXY,Elliptical,Radio RA=12H 54M 35.715S+/-0.03S,DEC=- J2000 V=+4628 SURF(V) = 19.0+/-1.0 Galaxy,Interacting 12D 34' 06.98"+/-0.5" SURF(I) = 17.5+/-1.0 Galaxy Comments: Coordinates calculated from WFPC2 u34q0501t jitter file 7862( 2) - 11/21/97 15:55 - [ 5] Visit: 01 Visit Priority: 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 NGC6251 NIC2 MULTIAC NIC2-FI F216N SAMP-SEQ=STEP64,NSAMP=24, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6251 NIC2 MULTIAC NIC2-FI F212N SAMP-SEQ=STEP64,NSAMP=24, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6251 NIC2 MULTIAC NIC2-FI F110W SAMP-SEQ=STEP8,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=339 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6251 NIC2 MULTIAC NIC2-FI F160W SAMP-SEQ=STEP8,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=339 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC6251 NIC2 MULTIAC NIC2-FI F205W SAMP-SEQ=STEP8,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH-CHOP, NUM-POS=8,DITH-SIZE=1.1625, CHOP-SIZE=97.0,PATTERN-ORIENT=339 ------------------------------------------------------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 6] Visit: 02 Visit Priority: 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 3C264 NIC2 MULTIAC NIC2-FI F216N SAMP-SEQ=STEP64,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 2 3C264 NIC2 MULTIAC NIC2-FI F212N SAMP-SEQ=STEP64,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C264 NIC2 MULTIAC NIC2-FI F110W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=25 ------------------------------------------------------------------------------------------------------------------------------------ 4 3C264 NIC2 MULTIAC NIC2-FI F160W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=25 ------------------------------------------------------------------------------------------------------------------------------------ 5 3C264 NIC2 MULTIAC NIC2-FI F205W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH-CHOP, NUM-POS=8,DITH-SIZE=1.1625, CHOP-SIZE=102.0,PATTERN-ORIENT=25 ------------------------------------------------------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 7] Visit: 03 Visit Priority: 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 3C278 NIC2 MULTIAC NIC2-FI F215N SAMP-SEQ=STEP64,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 2 3C278 NIC2 MULTIAC NIC2-FI F212N SAMP-SEQ=STEP64,NSAMP=22, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=9, DITH-SIZE=1.1625 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C278 NIC2 MULTIAC NIC2-FI F110W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=38.5 ------------------------------------------------------------------------------------------------------------------------------------ 4 3C278 NIC2 MULTIAC NIC2-FI F160W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH,NUM-POS=4, DITH-SIZE=1.1625, PATTERN-ORIENT=38.5 ------------------------------------------------------------------------------------------------------------------------------------ 5 3C278 NIC2 MULTIAC NIC2-FI F205W SAMP-SEQ=STEP16,NSAMP=13, 1 DEF CUM X PATTERN=SPIRAL-DITH-CHOP, NUM-POS=8,DITH-SIZE=1.1625, CHOP-SIZE=105.0, PATTERN-ORIENT=38.5 ------------------------------------------------------------------------------------------------------------------------------------ 7862( 2) - 11/21/97 15:55 - [ 8] Summary Form for Proposal 7862 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP64 NSAMP=24 PATTERN=SPIRAL-DITH NUM-POS=9 DITH-SIZE=1.1625 PATTERN-ORIENT=339 NUM-POS=4 CHOP-SIZE=97.0 NSAMP=22 PATTERN-ORIENT=25 NSAMP=13 CHOP-SIZE=102.0 PATTERN-ORIENT=38.5 SAMP-SEQ=STEP16 CHOP-SIZE=105.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F216N F212N F110W F160W F205W F215N ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6251 3C264 3C278 ------------------------------------------------------------------------------------------------------------------------------------