9142( 2) - 05/17/01 09:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9142 Version: 2 Check-in Date: 15-Feb-2001 17:27:16 1.Proposal Title: The Structure and Physics of Extragalactic Jets ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Eric Perlman University of Maryland Baltimore County CoI: Dr. Stefi Baum Space Telescope Science Institute N CoI: Dr. Chris O'Dea Space Telescope Science Institute N CoI: Dr. Andre Martel The Johns Hopkins University N CoI: Dr. Duccio Macchetto Space Telescope Science Institute N CoI: Dr. J. Patrick Leahy Manchester University N CoI: Dr. Daniel Harris Harvard/Smithsonian Center for N Astrophysics CoI: Dr. John Biretta Space Telescope Science Institute N CoI: Dr. William Sparks Space Telescope Science Institute N ------------------------------------------------------------------------------------ 5. Abstract As part of an ongoing investigation into the physics of jets, we propose to obtain WFPC2 polarimetry of the jets of 3C 264 and 3C 78. We are motivated by our recent findings of strong radio-optical polarimetry differences in the M87 jet, which imply that radio and optical synchrotron emitting electrons must occupy physically distinct regions, with high- energy particles concentrated closer to the jet axis, and affected more by shocks, than lower-energy particles. This is the first clear evidence regarding the internal structure of a relativistic jet. Here we propose to test whether our model holds in jets with different morphologies and luminosities, by obtaining high-resolution optical polarimetry of a sample of optical jets. This will produce fundamental gains in our knowledge of the structure and physics of extragalactic jets. By comparing the total intensity and polarized structures in the optical and radio, we will probe the magnetic field configurations in both optical and radio emitting regions. This will allow us to test the level of stratification in these jets, and uncover whether the magnetic field geometry is largely fixed at formation, or dominated by subsequent flow dynamics. By adding to the picture our optical spectral information, we will gauge the impact of shocks, the need for in situ particle acceleration, and test jet models. ------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 2] Observations Description ------------------------ We propose to obtain polarimetry of 3C 264 and 3C 78. These represent the next brightest nearby (z~0.02) optical jets after the prototype, M87. This proposal is motivated by our findings of strong differences between radio and optical polarized structure in the M87 jet at HST resolutions, which imply that radio and optical synchrotron emitting electrons in the M87 jet must occupy physically different regions, with different magnetic field configurations. This is the first clear evidence regarding the energetic and magnetic field structure of any relativistic jet. To better understand the physics of jets, it is critical to obtain polarimetry of other jets with different luminosities and structural details. In this way we can fully examine the range of structural properties (stratification, shocks, interactions between paticle populations at different energies, etc.) in extragalactic jets and fully explore the range of physical conditions. By probing the magnetic field configuration in a sample of jets, we may be able to address the question of whether the field geometry is largely fixed at formation, or produced by subsequent flow dynamics. Thus our study will provide desperately needed information about the structure, dynamics and formation of relativistic jets, which are the defining property in radio galaxies and Galactic mini-quasars. Of the instruments available for Cycle 10, only WFPC2 has polarimetric capability. The F555W filter is the ideal choice for polarimetry with the WFPC2, as it sits very close to the minimum for transmission of perpendicularly polarized light (WFPC2 Handbook, Figure 3.7). In addition, 5500 Angstroms is very close to the wavelength of maximum throughput for WFPC2. Note that while using a somewhat redder filter would slightly improve the throughput, it would greatly increase transmission of perpendicularly polarized light. Given the considerably greater distances of these objects (5 times more distant than M87), the full resolution of HST is required. We will use the PC and use sub-pixel dithering, combining the images at each ORIENT with tasks in the dither package. This should allow us to achieve the full ~ 0.05'' resolution which HST is capable of in the F555W band. This will allow us to achieve a linear resolution nearly equal to that of the WFPC2 polarization observations of M87 analyzed by Perlman et al. (1999), which were done with the WF chips and without dithering, therefore giving them only 0.2" resolution. To accomplish the dithering, we are using two patterns in RPS2: WFPC2-LINE for 3C 264 (2 positions separated by (5.5, 5.5) PC pixels), and WFPC2-BOX for 3C 78 (4 positions in a "box" inclined at 26.565 degrees, with vertices separated by 0.559 arcseconds). It would be possible to implement a 4-position dither for 3C 264, but it would entail a significant loss of observing time (because we would need to move within orbits), and therefore a loss of signal to noise, which is undesirable. Because we are using the PC for polarimetry, and we want a large, fairly regular shaped FOV, we will use the combination of POLQ+PC1-FIX+POS TARG +8,+8. Given the constraints in ISRs 95-03 and 97-11 this is the only combination that will give us an acceptable combination of FOV and resolution. To obtain images at three PAs (necessary to obtain Stokes I, Q and U), we will observe each object at three different epochs, specified by requiring ORIENTs approximately 60 degrees apart. Please note that this is the primary, indeed the only requirement for the orientations of the various visits. Any orientation will do so long as visits 1, 2, and 3 are about 60 degrees from one another and span a total of close to 120 degrees. Similarly for visits 4, 5 and 6. Data from the respective orients will be combined according to formulae from the WFPC2 Polarization Calibration tool. We have simulated observations of each object using the F702W snapshot images, assuming F_Nu \propto nu^-1 and the values in the WFPC2 Handbook for the efficiency of the WFPC2 + F555W + POLQ combination. We have required S/N >= 50 (after galaxy subtraction) in bright areas of the jet, translating to a 1 sigma detection limit of 2 degrees in PA and 2% in total polarization. By comparison, these jets have polarizations of ~ 20-30% in the radio, and (if they follow the pattern of M87 and 3C 273) they should be roughly equally polarized in the optical. Taking these requirements into account, we require 2 orbits per orientation of the HST+WFPC2+POLQ for 3C 264 and 4 orbits per orientation for 3C 78. Three observations, with different orientations of either the HST or POLQ, are required to obtain full polarization information (Stokes I, Q and U). Thus, 3C 264 requires 6 orbits and 3C 78 requires 12 orbits. In order to maximize the amount of observing time available per orbit, we are specifying CLOCKS=YES. We are also specifying four observations per orbit, to avoid saturating on the nucleus. Even though this decreases the total amount of observing time, this is very important, as it will most likely be necessary to use the nucleus to register the images. Accurate registration (within 0.1 pixel) is absolutely critical to obtaining the best science, and will not be possible if the nucleus is saturated. This large number of exposures per orbit also will help with cosmic-ray removal. In order to minimize the effect of variability, we have requested that visits 1-3 be scheduled (in any order) within 90 days of one another, and also that visits 4-6 be scheduled (in any order) within 90 days of one another. While we have no specific variability information for the jet components in these objects, typical variability timescales observed in M87's optical jet are several months. Real Time Justification ----------------------- Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 3 can be done before visit 1) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. We will be doing sub-pixel dithering to achieve the full ~0.05" resolution which HST is capable of in F555W. To accomplish the dithering, we are using two patterns in RPS2: WFPC2-LINE for 3C 264 (2 positions separated by (5.5, 5.5) PC pixels), and WFPC2-BOX for 3C 78 (4 positions in a "box" inclined at 26.565 degrees, with vertices separated by 0.559 arcseconds). It would be possible to implement a 4-position dither for 3C 264, but it would entail a significant loss of observing time (because we would need to move within orbits), and therefore a loss of signal to noise, which is undesirable. We would appreciate some feedback during the scheduling process so that the ORIENTS can be constrained more tightly. As explained in WFPC2 ISR 97-03, there is a significant area of the WFPC2 chevron which (when using POLQ) is impacted significantly by crosstalk. If there are stars which are ~15th mag or brighter in this region, some scattered light problems are possible. Each of these objects has a 15-16 mag star about 1 arcmin from the target. Under some orientations these stars might land in the crosstalk region, and possibly cause scattered light problems. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C264 GALAXY, RADIO GALAXY, RA=11H 45M 4.96S +/- 1", DEC=19D J2000 V = 14 GALAXY, JET 36' 23.0" +/- 1", PLATE-ID=019N Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 2 3C78 GALAXY, RADIO GALAXY, RA=03H 8M 26.22S +/- 1", DEC=04D J2000 V = 12.5 GALAXY, JET 6' 39.5" +/- 1", PLATE-ID=04YJ Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 9142( 2) - 05/17/01 09:37 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFPC2-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.3535 Coordinate_Frame POS-TARG Pattern_Orient 45 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFPC2-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.559017 Coordinate_Frame POS-TARG Pattern_Orient 26.565051 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 5] Visit: 01 Visit Priority: Visit Requirements: GROUP 1-3 WITHIN 90 D On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 3 can be done before visit 1) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C264 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES 2 1000 S PATTERN 1 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 6] Visit: 02 Visit Priority: Visit Requirements: GROUP 1-3 WITHIN 90 D ORIENT 45D TO 75D FROM 01 On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 3 can be done before visit 1) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C264 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES 2 1000 S PATTERN 1 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 7] Visit: 03 Visit Priority: Visit Requirements: GROUP 1-3 WITHIN 90 D ORIENT 105D TO 135D FROM 01 On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 3 can be done before visit 1) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C264 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES 2 1000 S PATTERN 1 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 8] Visit: 04 Visit Priority: Visit Requirements: GROUP 4-6 WITHIN 90 D On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 5 can be done before visit 4) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C78 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES,CR-SPLIT=0.5 2 1000 S PATTERN 2 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 9] Visit: 05 Visit Priority: Visit Requirements: GROUP 4-6 WITHIN 90 D ORIENT 45D TO 75D FROM 04 On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 5 can be done before visit 4) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C78 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES,CR-SPLIT=0.5 2 1000 S PATTERN 2 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 10] Visit: 06 Visit Priority: Visit Requirements: GROUP 4-6 WITHIN 90 D ORIENT 105D TO 135D FROM 04 On Hold Comments: Additional Comments: Please note that the only requirements for the ordering and scheduling of these observations are: (1) That the observations for each source be done within 90 days of one another (ordering does not matter, i.e., visit 5 can be done before visit 4) and (2) We need observations of each source located at 0, 60 and 120 relative to one another. Any PA will work for the fiducial point of this sequence so long as PA, PA+60 and PA+120 (both at +/- 15 degrees) are also available. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 3C78 WFPC2 IMAGE PC1-FIX F555W, CLOCKS=YES,CR-SPLIT=0.5 2 1000 S PATTERN 2 10 POS TARG 8, POLQ 8 ------------------------------------------------------------------------------------------------------------------------------------ 9142( 2) - 05/17/01 09:37 - [ 11] Summary Form for Proposal 9142 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CLOCKS=YES CR-SPLIT=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 1-3 WITHIN 90 D PATTERN 1 10 POS TARG 8, 8 GROUP 1-3 WITHIN 90 D ORIENT 45D TO 75D FROM 01 GROUP 1-3 WITHIN 90 D ORIENT 105D TO 135D FROM 01 GROUP 4-6 WITHIN 90 D PATTERN 2 10 POS TARG 8, 8 GROUP 4-6 WITHIN 90 D ORIENT 45D TO 75D FROM 04 GROUP 4-6 WITHIN 90 D ORIENT 105D TO 135D FROM 04 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W,POLQ ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C264 3C78 ------------------------------------------------------------------------------------------------------------------------------------