Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5428 Report Date: 18-Jul-95:17:22 Version: ********** Check-in Date: ********** 1.Proposal Title: TESTING THE ACCRETION DISK LINE-PROFILE HYPOTHESIS IN ARP 102B: CYCLE4MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO 1 Long Term yrs Sub Category RADIO GALAXIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Alexei V. Filippenko UC-BERKELEY USA 510-642-1813 ------------------------------------------------------------------------------------ 7. Abstract Arp 102B is the prototype of a set of ten broad-line radio galaxies whose hydrogen Balmer line profiles are double-peaked, and which share several additional distinguishing optical characteristics. We recently established the reality of this class through a comprehensive optical spectroscopic survey of radio-loud AGNs at z < 0.4 (Eracleous & Halpern 1992, 1993). We now propose to obtain moderate-resolution spectra to study the UV emission lines and nonstellar continuum of Arp 102B. Several theories have been suggested to explain the unusual line profiles; the most detailed is a model for emission from the photoionized atmosphere of an accretion disk. The Balmer lines are the only broad lines detected in ground-based spectra, and the optical nucleus is dominated by starlight. Both of these limitations restrict further progress in understanding the nature of this peculiar spectrum. But observations of the UV emission lines and continuum could test the models by (1) measuring line profiles of species with different ionization potentials, and (2) measuring the nonstellar continuum, which seems different from that of most AGNs. Disk photoionization models predict line shapes which are different among the UV lines. The same model predicts an ionizing continuum which is nonthermal, arising in an optically thin, ion-supported torus, rather than a blackbody accretion disk. If supported by the results of HST spectra, our study of Arp 102B could provide the most direct view of an accretion disk in an AGN. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.28 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5428 PI: Alexei V. Filippenko Proposal Title: TESTING THE ACCRETION DISK LINE-PROFILE HYPOTHESIS IN ARP 102B: CYCLE4MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Alexei V. Filippenko 1500 USA Jules P. Halpern 1770 USA Michael Eracleous 3470 USA Kaiyou Chen 2500 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. To detect faint lines, to model in detail the profiles of broad lines, and to determine the overall shape of the continuum, we require spectra having good S/N ratio and modest resolution over the entire accessible UV wavelength range. We will connect the red end of the UV spectrum (around 3150 A) with our optical spectra, obtained at ground-based observatories. This will give a reliable continuum shape over the range 1150-10000 A, and it will allow us to derive accurate emission-line intensity ratios between UV and optical lines. Three HST grating settings are needed, as follows: (1) FOS, G130H grating, 1150-1608 A, 1.0 A/diode, blue digicon. (2) FOS, G190H grating, 1573-2323 A, 1.5 A/diode, blue digicon. (3) FOS, G270H grating, 2227-3306 A, 2.1 A/diode, red digicon. The FOS spectra will be obtained through the 1" circular aperture. This yields excellent throughput and very good resolution; it also helps minimize the contribution of starlight. The first setting above gives us Ly-alpha and the blue half of C IV 1549, two very important lines. Most of the Ly-alpha profile will be redshifted away from the geocoronal emission. The second setting includes the red half of C IV 1549, He II 1640, and C III] 1909; the blue side of FOS is requested in order to get sufficient counts in the red half of the C IV profile (which falls in a very insensitive region of the FOS red side). The most important lines in the third setting are C II] 2326, [Ne IV] 2423, and Mg II 2800. We might also detect Fe II blends. Together, these grating settings will allow us to determine whether there is a UV bump in the continuum. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Only about 10 known AGNs have the double-peaked, broad emission lines which are characteristic of a rotating disk, but this class offers the most direct evidence for the reality of accretion disks around supermassive black holes. They are all too faint for IUE observations to be of great use. Arp 102B is the nearest and brightest candidate for accretion disk line emission; its H-alpha line profile is not HIGHLY variable, and its average appearance is consistent with the simple accretion-disk model. Until now, the hydrogen lines are the only broad lines which have been seen in Arp 102B. IUE observations of Arp 102B have resulted in weak detections of continuum and Ly-alpha. SWP and LWP exposures of duration 265 and 120 minutes, respectively, barely detected continuum in the 1600-3000 A range (Chen et al. 1989), consistent with an extrapolation of the optical continuum. The only UV emission line detected by IUE was Ly-alpha, but the resolution and S/N ratio are low. We must obtain a much better profile and a more accurate measurement the continuum shape if meaningful conclusions about the origin of the emission lines are to be drawn. Other, weaker UV lines must also be studied. HST is the only telescope that can provide the necessary data on the emission lines and nonstellar continuum. These data will test the theory of the origin of emission lines in a photoionized disk atmosphere. An important supporting piece of data that will aid in the interpretation of the ionizing continuum is the soft X-ray spectrum. X-ray observations of Arp 102B have already been obtained with the ROSAT PSPC, and will be available for archival analysis by the time the HST observations are made. Arp 102B lies at Galactic coordinates l = 75.5 deg, b = 34.9 deg. According to Burstein and Heiles (1982, AJ, 87, 1165), Galactic reddening is very small: E(B-V) = 0.015 mag. From the observed Balmer decrement of the narrow emission lines in Arp 102B, we deduce that the intrinsic reddening is also small. The total UV extinction is probably about 0.2 mag. From the IUE data of Chen et al. (1989), we estimate that the observed continuum flux density of Arp 102B at 1400 A, 1700 A, and 2300 A is 0.05 mJy, 0.10 mJy, and 0.18 mJy, respectively. We use these in what follows: FOS, G130H grating, blue digicon: At 1400 A, the efficiency is 0.055. The throughput of the 1" aperture is 0.90 for point sources, and we have 1.0 A/diode. Using equation (5) of Table 1.2.1 in the FOS Instrument Handbook, we find a count rate of 0.012 per second per diode. Zodiacal light, airglow, and diffuse Galactic light will not significantly affect our observations. The dark current is somewhat smaller than the expected signal; thus, the exposure time must be increased to achieve the desired S/N ratio, compared with the case of negligible dark current. We therefore require 240 minutes for S/N = 12 in the continuum at 1400 A. FOS, G190H grating, blue digicon: At 1700 A, the efficiency is 0.008 and the throughput it 0.91; there are 1.47 A/diode. For S/N = 16, we require 100 min. FOS, G270H grating, red digicon: At 2300 A, the efficiency is 0.052. The point-source throughput is 0.93, and there are 2.09 A/diode. For S/N = 32, we require only 33 minutes. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. None. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. When our HST observing dates become known, we will request nearly simultaneous time at Lick and Keck Observatories to obtain optical spectra and images, IR images, and IR spectra. These data will be combined with the UV spectra to construct an overall continuum spanning a large wavelength range. A complete analysis of the data will subsequently be done. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. 2590, Deep Imaging of the Site of SN 1961V. -- A. Filippenko, et al. 3507, UV Spectroscopy and High-Resolution Imaging of NGC 4395. -- A. Filippenko, W. Sargent, L. Ho 3519, UV Imaging of Nearby Galaxies. -- D. Maoz, A. Filippenko, et al. 3810, The Stellar Population of Wolf-Rayet Galaxies. -- P. Conti, A. Filippenko, W. Sargent, L. Ho, C. Leitherer, C. Robert, W. Vacca 4302, Supernovae and their Local Environment. -- A. Filippenko, et al. 4312, Circumstellar Material around Supernovae. -- A. Filippenko, et al. 4340, Origin of Blue Featureless Continuum in Seyfert 2 Nuclei. -- A. Filippenko, L. Ho 4350, FOS Observations of LINER Galaxy Nuclei. -- G. Reichert, A. Filippenko, L. Ho, J. Shields, R. Mushotzky, K. Mason, G. Branduardi-Raymont, C. Wu. 4635, Accretion Disk Line-Profile Hypothesis in Arp 102B. -- A. Filippenko, J. Halpern, M. Eracleous, K. Chen PUBLICATIONS: "A Gravitational Lens Candidate Discovered with the Hubble Space Telescope." D. Maoz, J. N. Bahcall, D. P. Schneider, R. Doxsey, N. A. Bahcall, A. V. Filippenko, W. M. Goss, O. Lahav, and B. Yanny; Astrophysical Journal (Letters), 386, L1 (1992). "HST Observations of NGC 4395, the Least Luminous Seyfert 1 Nucleus: Evidence Against the Starburst Hypothesis for Broad-Lined Active Galactic Nuclei." A. V. Filippenko, L. C. Ho, and W. L. W. Sargent; Astrophysical Journal (Letters), 410, L75 (1993). "NGC 4395: Evidence Against the Starburst Hypothesis for Seyfert 1 Nuclei and QSOs." A. V. Filippenko, L. C. Ho, and W. L. W. Sargent; in 16th Texas Symposium/3rd Symposium on Particles, Strings, and Cosmology; ed. C. Akerlof and M. Srednicki (New York: New York Academy of Sciences), 707 (1993). "Was SN 1961V a Genuine Supernova?" G. C. Bower, A. V. Filippenko, et al. BAAS, 25, 819 (1993). ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Both U. C. Berkeley and Columbia University have extensive computing facilities (VMS and UNIX) in their Astronomy Departments, as do STScI and Los Alamos National Laboratory. Image-processing workstations, graphics terminals, laser printers, large disks, and tape drives are all available. Many computer programs exist for analysis of data. Both universities also have many highly capable graduate students and postdoctoral fellows, some of whom may participate in various aspects of this project. Ground-based complementary observations can readily be obtained (with short notice) at Lick Observatory; proposals for Keck time will also be submitted by the PI. The usual secretarial and technical support is available at Berkeley, Columbia, Los Alamos, and STScI. ------------------------------------------------------------------------------------ 11. Address Information Name: ALEXEI V. FILIPPENKO Category: PI Institution: 1500 Address: DEPARTMENT OF ASTRONOMY 601 CAMPBELL HALL UNIVERSITY OF CALIFORNIA City: BERKELEY State: CA Zip Code: 94720 Country: USA Telephone: 510-642-1813 Telex (or e-mail): ALEX@BKYAST.BERKELEY.EDU ------------------------------------------------------------------------------------ Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5428 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 ARP102B E,303,315,320,910 RA = 17H 17M 56.34S +/- 1950.0 Z = 1 V = 16.0 +/- 0.3 0.04S, 0.02438 2 B-V = 1.0 +/- 0.2 DEC = +49D 01' 49.6" +/- 3 F-CONT(1400) = 7.6 +/- 2.3 E-16 0.6" 4 F-CONT(1600) = 1.0 +/- 0.3 E-15 5 F-CONT(2300) = 1.0 +/- 0.3 E-15 Comments: MAGNITUDES AND FLUXES REFER TO NUCLEUS ONLY. BRIGHT NUCLEUS SUPERPOSED ON FAINTER GALAXY BACKGROUND. THE ABOVE COORDINATES ARE PREFERRED OVER GASP COORDS. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5428 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 ARP102B FOS/RD ACQ/ 4.3 MIRROR SCAN-STEP- 1 1.4S 1 1 CYCLE 4 PEAK Y=1.204 2 ONBOARD ACQ FOR 2 SEARCH-SIZE-X=1 GROUP 1-7 WITHIN SEARCH-SIZE-Y=3 3D GROUP 1-6 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 2 ARP102B FOS/RD ACQ/ 1.0 MIRROR SCAN-STEP- 1 2.0S 1 1 CYCLE 4 PEAK X=.602 2 ONBOARD ACQ FOR 3 SCAN-STEP- Y=.602 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 ARP102B FOS/RD ACQ/ 0.5 MIRROR SCAN-STEP- 1 10S 1 1 CYCLE 4 PEAK X=0.30 2 ONBOARD ACQ FOR SCAN-STEP- 3.5 Y=0.30 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 3.5 ARP102B FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 10S 1 1 CYCLE 4 PEAK X=0.06 2 ONBOARD ACQ FOR 4 SCAN-STEP- Y=0.06 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 4 ARP102B FOS/RD ACCUM 1.0 G270H 2760 1 33M 32 5 1 CYCLE 4 Comments: IF THERE IS EXTRA TIME BEFORE EARTH OCCULTATION NEAR END OF EXPOSURE, CAN INCREASE EXPOSURE TIME TO INCREASE S/N RATIO. ------------------------------------------------------------------------------------------------------------------------------------ 5 ARP102B FOS/BL ACQ/ 0.3 MIRROR SCAN-STEP- 1 30S 1 2 CYCLE 4 PEAK X=0.06 2 ONBOARD ACQ FOR 6 SCAN-STEP- Y=0.06 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ARP102B FOS/BL ACCUM 1.0 G190H 1950 1 100M 16 4 2 CYCLE 4 Comments: IF THERE IS EXTRA TIME BEFORE EARTH OCCULTATION NEAR END OF EXPOSURE, CAN INCREASE EXPOSURE TIME TO INCREASE S/N RATIO. ------------------------------------------------------------------------------------------------------------------------------------ 6.1 ARP102B FOS/BL ACQ/ 4.3 MIRROR SCAN-STEP- 1 4.2S 1 1 CYCLE 4 PEAK Y=1.204 2 ONBOARD ACQ FOR SEARCH-SIZE-X=1 6.2 SEARCH-SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5428 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 6.2 ARP102B FOS/BL ACQ/ 1.0 MIRROR SCAN-STEP- 1 6.0S 1 1 CYCLE 4 PEAK X=.602 2 ONBOARD ACQ FOR SCAN-STEP- 6.3 Y=.602 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 6.3 ARP102B FOS/BL ACQ/ 0.5 MIRROR SCAN-STEP- 1 30S 1 1 CYCLE 4 PEAK X=0.30 2 ONBOARD ACQ FOR SCAN-STEP- 6.5 Y=0.30 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 6.5 ARP102B FOS/BL ACQ/ 0.3 MIRROR SCAN-STEP- 1 30S 1 1 CYCLE 4 PEAK X=0.06 2 ONBOARD ACQ FOR 7 SCAN-STEP- Y=0.06 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 7 ARP102B FOS/BL ACCUM 1.0 G130H 1380 1 240M 14 3 3 CYCLE 4 Comments: IF THERE IS EXTRA TIME BEFORE EARTH OCCULTATION NEAR END OF EXPOSURE, CAN INCREASE EXPOSURE TIME TO INCREASE S/N RATIO. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5428 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.204 SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-X=.602 SCAN-STEP-Y=.602 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.30 SCAN-STEP-Y=0.30 SEARCH-SIZE-X=3 SCAN-STEP-X=0.06 SCAN-STEP-Y=0.06 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.28 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category RADIO GALAXIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ONBOARD ACQ FOR 2; GROUP 1-7 WITHIN 3D; GROUP 1-6 NO GAP ONBOARD ACQ FOR 3; ONBOARD ACQ FOR 3.5 ONBOARD ACQ FOR 4 ONBOARD ACQ FOR 6 ONBOARD ACQ FOR 6.2 ONBOARD ACQ FOR 6.3 ONBOARD ACQ FOR 6.5 ONBOARD ACQ FOR 7 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H G190H G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names ARP102B ------------------------------------------------------------------------------------------------------------------------------------