9493( 10) - 07/22/02 10:31 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9493 Version: 10 Check-in Date: 22-Jul-2002 10:30:44 1.Proposal Title: Revealing the nature of low luminosity radio-galaxies with imaging polarimetry ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Alessandro Capetti Osservatorio Astronomico di Torino CoI: Dr. David Axon University of Hertsfordshire N CoI: Dr. Annalisa Celotti International School for Advanced Studies N CoI: Dr. Marco Chiaberge Space Telescope Science Institute N CoI: Dr. Duccio Macchetto Space Telescope Science Institute N CoI: Dr. William Sparks Space Telescope Science Institute N ------------------------------------------------------------------------------------ 5. Abstract HST imaging of low luminosity FR I radio-galaxies allowed us to isolate for the first time their optical nuclear emission from that of the host galaxy. Fluxes of these unresolved nuclear sources strongly correlate with those of the radio- cores, suggesting a common non-thermal origin. The picture which emerges is that these radio-galaxies differ in many fundamental aspects from the other classes of AGN as they might be lacking the substantial BLR, thermal disk emission and torii, usually associated to active nuclei, probably reflecting a fundamentally different accretion mode. On the other hand, these results support the identification of FR I as the misoriented population of BL Lac objects. It is crucial at this stage to firmly establish the synchrotron origin of these nuclear sources. A simple and direct test can be performed by measuring their polarization. In case of synchrotron emission we expect to detect significant nuclear polarization, as routinely measured in BL Lac objects, at level of 3 - 20 \ We thus propose to obtain imaging polarimetry of a sample formed by the 9 nearest FR I radio- galaxies. ------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 2] Observations Description ------------------------ The targets of these observations are represented by a central point source superposed to the galaxy background. The typical central surface brightness of the host galaxies is Mu_R ~ 15.5 - 16.5 mag arcsec^-2 while fluxes of the nuclear sources selected for this proposal are in the range 10^-17 - 10^-15 erg s^-1 cm^-2 AA^-1 (R ~ 16 - 20). The preferred wavelength range for these observations is the V band using the broad V filter F606W in combination with one of the visible polarizer filters, POL0V, POL60V and POL120V. In this band the ACS/HRC reaches the peak of its efficiency and the POL0V filter has the highest ratio between its parallel and perpendicular transmission, an important factor to determine accurately the polarization properties of the targets. The strategy to obtain ACS/HRC polarization images requires the target to be imaged with all 3 polarizers, each of them being associated to a different polarization angle, separated by 60^degrees. The accuracy of polarization measurements is limited essentially by the signal-to-noise ratio (SNR) achieved in each of these individual images and by the polarization calibration accuracy (see Sparks and Axon 1999, for a review of the HST polarization data analysis). Concerning the statistical accuracy, the error in the polarization level derived from the combination of images taken with polarizers at three position angles scales as sigma_P ~ 1 / SNR where SNR is the signal to noise in the individual polarization images. To reach an accuracy of 1 get a SNR >~ 100 in each of the three images. In one orbits, taking into account telescope and instrument overheads, we can obtain 3 images of ~ 650 s, each of them split in two exposures for cosmic rays rejection. With an exposure time of 650 s in the F606W filter such a SNR ratio is reached at a flux density of 1.5 \cdot 10^-17 erg s^-1 cm^-2 AA^-1 (R hand, the galaxy emission can be imaged with the proposed exposure time at a SNR ~ 15 per pixel. With a moderate rebinning to 0arcs2 resolution we will achieve a detection threshold of polarization of 1 \ which will enable us to accurately map the nuclear radiation field. Real Time Justification ----------------------- None None Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C31 GALAXY, RADIO GALAXY, RA=01H 7M 25.0S +/- 0.5", J2000 Z = F(7020)=1.5+/-0.1e-17 ELLIPTICAL DEC=32D 24' 44.8" +/- 0.5" 0.0169 SURF-CONT-BKG(7020)=4.9+/-0.2e-16 Coordinate Source: HST_IMAGE 2 3C66B GALAXY, RADIO GALAXY, RA=2H 23M 11.1S +/- 0.5", J2000 Z = F(7020)=4.9+/-0.1e-17 ELLIPTICAL DEC=42D 59' 34.3" +/- 0.5" 0.0215 SURF-CONT-BKG(7020)=3.3+/-0.2e-16 Coordinate Source: HST_IMAGE 3 3C264 GALAXY, RADIO GALAXY, RA=11H 45M 5.0S +/- 0.5", J2000 Z = F(7020)=11.4+/-0.3e-17 ELLIPTICAL DEC=19D 36' 23.2" +/- 0.5" 0.0206 SURF-CONT-BKG(7020)=3.6+/-0.2e-16 Coordinate Source: HST_IMAGE 4 3C270 GALAXY, RADIO GALAXY, RA=12H 19M 23.2S +/- 0.5", J2000 Z = F(7020)=0.5+/-0.1e-17 ELLIPTICAL DEC=05D 49' 29.9" +/- 0.5" 0.0075 SURF-CONT-BKG(7020)=9.1+/-0.2e-16 Coordinate Source: HST_IMAGE 5 3C272.1 GALAXY, RADIO GALAXY, RA=12H 25M 4.0S +/- 0.5", J2000 Z = F(7020)=5.9+/-0.2e-17 ELLIPTICAL DEC=12D 53' 13.8" +/- 0.5" 0.0037 SURF-CONT-BKG(7020)=14.8+/-0.2e-16 Coordinate Source: HST_IMAGE 6 3C274 GALAXY, RADIO GALAXY, RA=12H 30M 49.5S +/- 0.5", J2000 Z = F(7020)=39.0+/-0.2e-17 ELLIPTICAL DEC=12D 23' 29.2" +/- 0.5" 0.0037 SURF-CONT-BKG(7020)=4.8+/-0.2e-16 Coordinate Source: HST_IMAGE 7 3C296 GALAXY, RADIO GALAXY, RA=14H 16M 52.9S +/- 0.5", J2000 Z = F(7020)=0.4+/-0.1e-17 ELLIPTICAL DEC=10D 48' 27.9" +/- 0.5" 0.0237 SURF-CONT-BKG(7020)=6.5+/-0.2e-16 Coordinate Source: HST_IMAGE 8 3C465 GALAXY, RADIO GALAXY, RA=23H 38M 29.4S +/- 0.5", J2000 Z = F(7020)=1.9+/-0.1e-17 ELLIPTICAL DEC=27D 01' 53.1" +/- 0.5" 0.0302 SURF-CONT-BKG(7020)=2.1+/-0.2e-16 Coordinate Source: HST_IMAGE 9 3C449 GALAXY, RADIO GALAXY, RA=22H 31M 20.6S +/- 0.5", J2000 Z = F(7020)=1.8+/-0.1e-17 ELLIPTICAL DEC=39D 21' 29.8" +/- 0.5" 0.0181 SURF-CONT-BKG(7020)=3.3+/-0.2e-16 Coordinate Source: HST_IMAGE 9493( 10) - 07/22/02 10:31 - [ 4] 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 3C31 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 796 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C31 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 796 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C31 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 796 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 5] 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 3C66B ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 824 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C66B ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 824 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C66B ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 824 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 6] 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 3C264 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C264 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C264 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 11 3C264 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL0UV ------------------------------------------------------------------------------------------------------------------------------------ 12 3C264 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL60UV ------------------------------------------------------------------------------------------------------------------------------------ 13 3C264 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL120UV ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 7] Visit: 04 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 3C270 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C270 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C270 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 8] Visit: 05 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 3C272.1 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C272.1 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C272.1 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 9] Visit: 06 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 3C274 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C274 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C274 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 300 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 11 3C274 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL0UV ------------------------------------------------------------------------------------------------------------------------------------ 12 3C274 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL60UV ------------------------------------------------------------------------------------------------------------------------------------ 13 3C274 ACS/HR ACCUM HRC F330W, CR-SPLIT=2 1 300 S C POL120UV ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 10] Visit: 07 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 3C296 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C296 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C296 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 782 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 11] Visit: 08 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 3C465 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 786 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C465 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 786 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C465 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 786 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 12] Visit: 09 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 3C449 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 808 S C POL0V ------------------------------------------------------------------------------------------------------------------------------------ 2 3C449 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 808 S C POL60V ------------------------------------------------------------------------------------------------------------------------------------ 3 3C449 ACS/HR ACCUM HRC F606W, CR-SPLIT=2 1 808 S C POL120V ------------------------------------------------------------------------------------------------------------------------------------ 9493( 10) - 07/22/02 10:31 - [ 13] Summary Form for Proposal 9493 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W,POL0V F606W,POL60V F606W,POL120V F330W,POL0UV F330W,POL60UV F330W,POL120UV ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C31 3C66B 3C264 3C270 3C272.1 3C274 3C296 3C465 3C449 ------------------------------------------------------------------------------------------------------------------------------------