15225( 2) - 14-Jul-2017 12:54:56 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15225 Version: 2 Check-in Time: 14-Jul-2017 12:54:56 STScI Edit Number: 0 Title NGC 3147, a Golden true Type 2 AGN? ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Stefano Bianchi Universita' degli Studi Roma Tre Y CoI: Dr. Marco Chiaberge Space Telescope Science Institute - ESA Y CoI: Prof. Robert Antonucci University of California - Santa Barbara N CoI: Dr. Ari Laor Technion-Israel Institute of Technology N CoI: Dr. Alessandro Capetti Osservatorio Astronomico di Torino N CoI: Mr. Riccardo Middei Universita' degli Studi Roma Tre N CoI: Prof. Giorgio Matt Universita' degli Studi Roma Tre N CoI: Dr. Andrea Marinucci Universita' degli Studi Roma Tre N CoI: Dr. Francesca Panessa INAF-Istituto di Astrofisica e N Planetologia Spaziali CoI: Dr. Francisco J Carrera Instituto de Fisica de Cantabria N CoI: Dr. Loredana Bassani INAF, Istituto di Fisica Spaziale e Fisica N Cosmica-Bologna CoI: Prof. Fabio La Franca Universita' degli Studi Roma Tre N ------------------------------------------------------------------------------------ Abstract The AGN unification scheme suggests that Type 2 AGN are identical to type 1 AGN, just observed from the side, where an inner torus structure obscures a direct view of the continuum and broad line region (BLR) emission. Is this unification scheme always true? In some low luminosity type 2 AGN we have a direct view of the innermost regions, as indicated by an unabsorbed and rapidly variable X-ray emission, yet no broad lines are observed. Are these true Type 2 AGN (i.e. the BLR is truly missing), or is the BLR emission just hard to detect in these weak AGN? Here we propose to address this question with the best true Type 2 AGN candidate, namely NGC 3147. If the narrow slit HST spectrum of the nucleus does not reveal the expected very broad and weak H alpha emission, then NGC 3147 can be declared as a Golden true type 2 AGN. It will show beyond any doubt that such objects do exist. If the BLR is detected, with the predicted extremely large line width, it will provide a stringent test of the mass scaling relations widely used and accepted by the community, opening up the possibility to measure directly the BH mass in nearby weakly active galaxies. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe the target for 1 orbit using STIS/CCD and the G750L grating. The observations are aimed at detecting a relatively bright but potentially very broad H emission line. In ground based spectra, the emission of such a line, if present, is heavily contaminated by the host galaxy stellar emission. We will use the 52x0.1 slit in order to 15225( 2) - 14-Jul-2017 12:54:56 - [ 2] reduce such a contamination by a factor of ~ 10 with respect to ground based observations. The use of the 0.1" slit has a great advantage with respect to wider slits because of the increased contrast with respect to both the stellar continuum and the narrow component of the emission line, which is mostly produced in the extended (kpc-scale) narrow line region. The pointing will be aimed at the host galaxy photocenter as known from the literature. A target acquisition image will be taken to allow recentering on the brightest region, where we expect a faint AGN to be visible. As recommended in the STIS handbook, we will use the F28X50LP filter for the acquisition image and an exposure time of 60s, which is appropriate for the expected surface brightness of ~15 mag arcsec^-2. We do not request a peakup, since the nucleus of the galaxy is diffuse. The STIS handbook states that the centering accuracy is ~0.1" for a diffuse target. In order to avoid missing the AGN at the center of the galaxy nucleus, we will obtain 5 spectra. The first will be centered at the location derived following the acquisition image. The following will be taken with a POS-TARG of (+0.1, 0.0), (+0.2, 0.0), (-0.1, 0.0), (-0.2, 0.0). This strategy is identical to previous successful programs aimed at studying faint AGN in low luminosity objects similar to our target, and/or to derive the stellar kinematics with the aim of measuring the BH mass in nearby galaxies (e.g. GO 7403, GO 8228). The short exposure times needed for these observations allow us to fit all five pointings and the acquisition image into one single orbit. We performed accurate S/N simulations using the STIS ETC. The stellar continuum within the 0.1" slit is expected to be F_lam ~2 x 10^-16 erg cm^-2 s^-1 A^-1, using the information derived from ground based spectra with a 1" slit centered onto the nucleus of the target. The broad emission line is expected to have a flux F(Halpha) ~ 1 x 10^-13 erg cm^-2 s^-1. Based on its bolometric luminosity and BH mass, the width of the line is expected to be up to 40, 000 km s^-1 (see Eq. 1). This extremely large width of the line prevents us from using a higher resolution grating, but note that ground-based observations already exclude narrower components with high confidence (Bianchi et al., 2008). We use the 52x01E1 aperture to mitigate CTE losses, as suggested by the IHB, Sect 7.3.8. 15225( 2) - 14-Jul-2017 12:54:56 - [ 3] We use two CR-SPLIT images at each slit position to eliminate cosmic rays in our relatively short exposures. We also include simultaneous flat fields to perform de-fringing at long wavelengths, as recommended by the IHB in Sect. 7.2.6. These flats are taken during occultation, immediately after the last on-target exposure. ------------------------------------------------------------------------------------ 15225( 2) - 14-Jul-2017 12:54:56 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-3147 GALAXY, SEYFERT RA=10H16M53.6509S, J2000 V = 11.43 DEC=+73D24'2.70" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the NED database. The magnitude is the magnitude of the entire galaxy, not the nucleus. Expected nuclear fluxes are given in the Phase I proposal and in the description of the Observations ------------------------------------------------------------------------------------------------------------------------------------ 15225( 2) - 14-Jul-2017 12:54:56 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-3147 STIS/CCD ACQ F28X50LP MIRROR 1 60 S (60 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-3147 STIS/CCD ACCUM 52X0.1E1 G750L 7751 1 400 S see below (410 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-3147 STIS/CCD ACCUM 52X0.1E1 G750L 7751 1 400 S POS TARG 0.1, +0.0 see below (410 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-3147 STIS/CCD ACCUM 52X0.1E1 G750L 7751 1 400 S POS TARG 0.2, +0.0 see below (410 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-3147 STIS/CCD ACCUM 52X0.1E1 G750L 7751 1 400 S POS TARG -0.1, -0.0 see below (410 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-3147 STIS/CCD ACCUM 52X0.1E1 G750L 7751 1 400 S POS TARG -0.2, -0.0 see below (410 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/CCD ACCUM 52X0.1 G750L 7751 2 DEF (0 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-3147 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A NGC-3147 2 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 1 1 205.0 S NGC-3147 2 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 2 1 205.0 S NGC-3147 3 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 1 1 205.0 S NGC-3147 3 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 2 1 205.0 S NGC-3147 4 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 1 1 205.0 S NGC-3147 4 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 2 1 205.0 S NGC-3147 5 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 1 1 205.0 S NGC-3147 5 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 2 1 205.0 S NGC-3147 6 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 1 1 205.0 S NGC-3147 6 STIS/CCD ACCUM 52X0.1E1 G750L 7751 none none none 2 1 205.0 S 15225( 2) - 14-Jul-2017 12:54:56 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ CCDFLAT 7 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 1 none 1 N/A CCDFLAT 7 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 2 none 1 N/A 15225( 2) - 14-Jul-2017 12:54:56 - [ 7] Summary Form for Proposal 15225 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.1, 52X0.1E1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG -0.1, -0.0, POS TARG -0.2, -0.0, POS TARG 0.1, +0.0, POS TARG 0.2, +0.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G750L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names CCDFLAT, NGC-3147 ------------------------------------------------------------------------------------------------------------------------------------