Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5684 Report Date: 18-Jul-95:17:51 Version: ********** Check-in Date: ********** 1.Proposal Title: GEOMETRY AND GENERALIZABILITY OF THE REFLECTED LIGHT MODEL FOR SEYFERT 2 GALAXIES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO Sub Category SEYFERTS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Ross D Cohen CENTER FOR ASTROPHYSICS & SP USA ------------------------------------------------------------------------------------ 7. Abstract The polarized flux spectra of at least 8 Seyfert 2 galaxies look like the flux spectra of Seyfert 1 nuclei, and the polarization position angles are generally perpendicular to the radio structure axes. This and other evidence suggests that all Seyfert 2 galaxies may have Seyfert 1 spectra visible only in reflected light. The broad-line regions can be viewed directly in the cases where the otherwise obscuring tori are viewed pole on, and such objects would be classified as Seyfert 1 galaxies. It is crucial to determine whether this generalization of the polarization results is correct, and in particular whether all Seyfert 2 galaxies have polarized nuclear continuua with position angles perpendicular to the radio source axes. We argue that contamination by host-galaxy starlight usually renders this virtually impossible to determine from the ground, while from space, the observations would be easy and straightforward. We can use the FOS on the HST as a polarimeter, cutting down drastically on the starlight by observing in the UV where the stellar flux is weak. We can also determine the geometry of the obscuring regions, and for many of the objects, we can determine whether the mechanism of the polarization is dust or electron scattering. We can determine continuum slopes and identify broad Fe II features from the flux spectra we receive as a by-product of the polarimetry. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.69 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5684 PI: Ross D Cohen Proposal Title: GEOMETRY AND GENERALIZABILITY OF THE REFLECTED LIGHT MODEL FOR SEYFERT 2 GALAXIES ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Ross D Cohen CENTER FOR ASTROPHYSICS & SPACE USA SCIENCES Robert Rj Antonucci UCSB USA Laura E Kay BARNARD COLLEGE USA Julian H Krolik JOHNS HOPKINS UNIVERSITY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will do broad-band polarimetry of 2 Seyfert 2 galaxies using the FOS, large aperture, red detector, the G270H grating, and B Waveplate. We will obtain a S/N of approximately 5 or greater in the polarized flux by binning the spectrum between 2100 Angstroms and 3000Angstroms , assuming that P = 3\%. To minimize spacecraft inefficiency, we will take no exposure shorter than 20m, shorter than the usually available orbital period. This will allow us multiple wavelength points (from two to 11) for several objects at the same SNR, enabling us to determine crudely the wavelength dependence of the polarization. (This should be sufficient to distinguish electron scattering from dust scattering.) The total sample is large enough to enable us to determine unambiguously whether Seyfert 2 galaxies have reflected featureless continua and what the geometry of the occulting region is (if any). The SNR of 5 in the polarized flux will produce a PA accurate to 6 degrees, allowing us to determine unambiguously whether P is large or small and whether the PA are aligned (like Seyfert 1 galaxies and quasars) or perpendicular to the radio structure axis. Target acquisition will be non-standard. We have derived coordinates in the guide star system from published coordinates for the objects and for the reference stars (which are all in the guide star catalog). For these objects, three stage peak-up to center the objects to within 0.21" in Y (suitable for observing in the large aperture (see CAL/FOS 132). An earlier technique using offsets followed by small peak-ups was found not to be completely successfull. Integration times are arbitrarily set to 5 seconds because of uncertainty in the fraction of total flux in the compact nucleus. No special requirements are placed on the operation of the spacecraft, and there will be no requirements for calibration beyond the routine FOS calibration procedure. The polarization sequence itself should not be interrupted. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The number of Seyfert 2 galaxies for which featureless continuum polarization may be determined from ground--based observations is strictly limited to the nearest objects and those with the strongest continuum polarizations. This technique has been pushed to its limits by one of us (L. K.). Thus, it is not known whether the finding of Miller and collaborators that a few Seyfert 2 galaxies show a reflected Type 1 spectrum applies to only a small subset of Seyfert 2s or to all of them. Our sample will yield an unbiased, unambiguous result for a large enough sample to settle the question of whether Seyfert 2 galaxies have an occulted source of non--stellar continuum. For the majority of Seyfert 2 galaxies, continuum polarization is impossible to determine from the ground due to contamination by polarized starlight, regardless of S/N. No space- -based polarimeter capable of making these measurements exists other than on the HST. The unique ability of the HST to perform ultraviolet polarimetry will enable us to resolve this important question. This ability will be lost after the installation of the COSTAR. For a given number of detected counts, (C), and modulation efficiency, (E), the signal--to--noise in a polarization measurement is: S/N = (E * P * C)/ (sqrt(2) *sqrt(C)) The factor of sqrt(2) comes from the conversion of Q and U to P. This formula reproduces the results in the original FOS Instrument Handbook (page C--9). To determine the count rate, we have used the latest values for the HST and FOS efficiency determined by the FOS IDT and included in the FOS simulator program, but we have multiplied the result by a factor of 0.5 because the FOS polarimeter can measure only one ray at a time and by another factor of 0.8 for the waveplate transmission at 2500Angstroms . The modulation efficiency at 2537Angstroms is 0.77 (See the current FOS handbook, page 22 and 23 for waveplate transmission and modulation efficiency.) The objects are bright enough that sky and dark are negligible, even using the large aperture. We have estimated the nuclear continuum fluxes at 2500Angstroms from the IUE measurements. Assuming a power law index of alpha = 1.3, F(nu) proportional to nu^(-alpha) (the medians from the acceptable quality IUE data), and a P of 3%, we will aim for a polarized flux SNR of at least 5. With a dispersion of 2.05Angstroms /diode we will bin over the 425 diodes between 2125Angstroms and 3000Angstroms . Using the above factors, an object with F(lambda)=1.0 * 10^(-15) erg cm^(-2) s^(-1) Angstroms ^(-1) at 2500Angstroms would yield approximately 190 counts s^(-1) in this range, without the use of the polarimeter. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The investigators have worked for the FOS IDT and have extensive experience both with the FOS and astronomical polarimetry. We will analyze the data at UCSD and UCSB. Processing is basically the same as for FOS spectral data. It is additionally necessary to add and difference the spectra taken at the different waveplate position angles to create the unnormalized Q and U polarized flux spectra, which are then divided by the modulation efficiency curve and added in quadrature to produce the total polarized flux. (The Q and U spectra will be binned to increase the S/N.) SDAS and IRAF will provide most or all of the necessary routines, along with a package of polarimetry routines written for VISTA, an image and spectral reduction/analysis package developed at the University of California. We expect that we can produce P and Theta almost immediately for each object which is observed. For those which are polarized and which do not have adequate radio maps, we will undertake to make appropriate maps. Improved maps can be acquired by using the VLA at 2~cm or 3.6cm (with the sensitive ``Voyager'' receivers). Results for the data will be published prior to making these new maps as the P measurements alone yield a valid scientific result. The distribution of P will be used to construct new models of the obscuring region. Page 4 ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Typical sky survey images are burned out in the cores of these bright objects, hence the accurate coordinates necessary for FOS target acquisition must be acquired other than from the guide star plates. For many of these objects Clements and Argyle have measured accurate coordinates, and Argyle has provided us with the coordinates of the reference stars, which are measurable on the guide star plates. Because binary search target acquisition requires fluxes known to better than a factor of two over the range of wavelength to which the red tube is sensitive, and within the 4.3" aperture, we will not use it. See queston 3, section 2. objects using the derived coordinates, and then center them perpendicular to the diode array using a peakup in the 1". As required, polarimetry of nearby stars to refine measurements of galactic interstellar polarization can be acquired as necessary at Lick Observatory. New radio maps may be made as a follow--up. Their acquisition will not delay the output of our polarimetry results. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Antonucci and Cohen have worked on FOS--Team GTO data, but they are not co-- investigators. Antonucci has only just received cycle 1 GO data on NGC 1068 (program 2077), a related project. He has also received data on the unrelated program 2177. Antonucci, Cohen, Kay and Krolik are also co--investigators on one or more related cycle 2 proposals from which no data have been received. The only data on which we have worked so far are GTO data, which are not ours. Some of this (on NGC1068: see below) are related to this proposal. We are working on a range of AGN and Quasar data taken by the FOS IDT with H. Ford or M. Burbidge as P.I. Antonucci has worked on NGC1068 emission line imaging and nuclear spectrophotometry in which much has been learned about the occultation/reflection model for this prototype, eg that we can pinpoint the obscured nucleus at the emission line cone apex, and that it is located at the megamaser position. We are now using VLBI velocity field observations of the maser in an attempt to detect dynamically and to weigh the putative supermassive black hole. The small- -aperture spectrophotometry and the imaging have provided evidence that the mirror is spatially extended, verifying a theoretical prediction by Miller, Mathews, and Goodrich (Ap. J., in press). ``FOS Spectroscopy of Resolved Structure in the Nucleus of NGC~1068'', S. Caganoff, R.R.J. Antonucci, H.C. Ford, G.A. Kriss, G. Hartig, L. Armus, I.N. Evans, E. Rosenblatt, R.C. Bohlin and A.L. Kinney, {\bit Ap. J. Lett.}, in press, 1992. ``HST Line Imaging of the Inner 3 Arcseconds NGC~1068 in the Light of [O~III]$\lambda$5007'', I. Evans, H. Ford, A. Kinney, R. Antonucci, S. Caganoff and L. Armus, {\bit Ap. J. Lett.} {\bbf 369}, L27, 1991). ``Far UV Spectroscopy of the QSO UM 675 with the FOS on the Hubble Space Telescope'', E. Beaver, E. Burbidge, R. Cohen, V. Junkkarinen, R. Lyons, E. Rosenblatt, G. Hartig, B. Margon, and A. Davidsen, {\bit Ap. J. Lett.} {\bbf 377}, L1. ``Faint Object Spectrograph Observations of CSO 251'', R. D. Cohen, E. A. Beaver, E. M. Burbidge, V. T. Junkkarinen, R. W. Lyons, and E. I. Rosenblatt'', in {\bit The First Year of HST Observations}, A. L. Kinney and J. C. Blades, eds., page 204. ``The Conditions in the z=0.692 Absorber Towards 3CR 286'', R. D. Cohen, E. A. Beaver, V. T. Junkkarinen, T. A. Barlow, R. W. Lyons, and H. E. Smith'', \Apj, submitted. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). All computing facilities required for data reduction and analysis and any theoretical follow--up already exist at our institutions and are available largely free of charge. Any necessary supporting optical polarimetric observations will be done at University of California facilities. We hope to involve students in this work, provided that support is provided by this grant. ------------------------------------------------------------------------------------ 11. Address Information Page 5 Name: ROSS D COHEN Category: PI Institution: Center for Astrophysics & Space S Address: CASS 0111, UCSD 9500 GILMAN DRIVE City: LA JOLLA State: CA Zip Code: 920930111 Country: USA Telephone: 619-534-2664 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5684 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 MRK463E E,312,923,924 RA = 13H 56M 2.920S +/- 2000 Z = 1 V = 14.2 +/- .5 0.3", .0505 2 F-CONT(2500) = 4.0 +/- 1.0 E-15 DEC = 18D 22' 18.83" +/- 0.3", PLATE-ID=019M ------------------------------------------------------------------------------------------------------------------------------------ 2 MARK34 E,312,923,924 RA = 10H 34M 8.573S +/- 2000 Z = 1 V = 14.7 +/- .5 0.3", .0515 2 F-CONT(2500) = 1.3 +/- 0.5 E-15 DEC = 60D 1' 52.01" +/- 0.3", PLATE-ID=01S0 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5684 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 MRK463E FOS/RD ACQ/ 4.3 MIRROR SEARCH-SIZE-X=1 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=3 2.0 SCAN-STEP- SEQ 1.0-4.0 NO GAP Y=1.23 CYCLE 4 / 1.0-4.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 MRK463E FOS/RD ACQ/ 1.0 MIRROR SEARCH-SIZE-X=6 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=2 3.0 SCAN-STEP- X=0.61 SCAN-STEP- Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 3 MRK463E FOS/RD ACQ/ 0.5 MIRROR SEARCH-SIZE-X=3 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=3 4.0 SCAN-STEP- X=0.29 SCAN-STEP- Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 4 MRK463E FOS/RD ACCUM 4.3 G270H POLSCAN=4B 1 1200S 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 11 MARK34 FOS/RD ACQ/ 4.3 MIRROR SEARCH-SIZE-X=1 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=3 12.0 SCAN-STEP- SEQ 11.0-14.0 NO Y=1.23 GAP CYCLE 4 / 11.0- 14.0 ------------------------------------------------------------------------------------------------------------------------------------ 12 MARK34 FOS/RD ACQ/ 1.0 MIRROR SEARCH-SIZE-X=6 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=2 13.0 SCAN-STEP- X=0.61 SCAN-STEP- Y=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 13 MARK34 FOS/RD ACQ/ 0.5 MIRROR SEARCH-SIZE-X=3 1 5S 1 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=3 14.0 SCAN-STEP- X=0.29 SCAN-STEP- Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 14 MARK34 FOS/RD ACCUM 4.3 G270H POLSCAN=4B 1 1200S 2 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5684 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.23 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.61 SCAN-STEP-Y=0.61 SEARCH-SIZE-X=3 SCAN-STEP-X=0.29 SCAN-STEP-Y=0.29 POLSCAN ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.69 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category SEYFERTS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2.0; SEQ 1.0-4.0 NO GAP; CYCLE 4 / 1.0-4.0; ONBOARD ACQ FOR 3.0; ONBOARD ACQ FOR 4.0; ONBOARD ACQ FOR 12.0; SEQ 11.0-14.0 NO GAP; CYCLE 4 / 11.0-14.0; ONBOARD ACQ FOR 13.0; ONBOARD ACQ FOR 14.0; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names MRK463E MARK34 ------------------------------------------------------------------------------------------------------------------------------------