12285( 2) - 12-Jul-2010 15:23:42 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12285 Version: 2 Check-in Time: 12-Jul-2010 15:23:42 STScI Edit Number: 0 Title Mapping the core and lobes of the extraordinary FRII microquasar in NGC 7793 ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Roberto Soria Mullard Space Science Laboratory CoI: Prof. Manfred Pakull Universite de Strasbourg I N CoI: Dr. Jess Broderick University of Southampton N CoI: Dr. Christian Motch Universite de Strasbourg I N ------------------------------------------------------------------------------------ Abstract We have discovered an extraordinary microquasar in NGC 7793, with all the textbook physical structures of an FRII radio galaxy: an X-ray/optical core, X-ray and radio hot spots, radio lobes, and a large cocoon with radio, X-ray and optical line emission. It reveals a new class of accreting black holes dominated by mechanical power even at high accretion rates; it is the missing link between ordinary microquasars and ultraluminous X-ray sources. After studying the system with radio, X-ray and ground-based optical telescopes, we propose a WFC3/UVIS study. We will: a) resolve and constrain the nature of the black hole counterpart; b) map density structures in the nebula (knots, filaments), measure their UV and optical line flux, and model the shock excitation process; c) resolve the forward and reverse shock, and map the outer edge of the expanding shell; d) study the age and metallicity of the surrounding stellar population. Our goals are to determine the mass and total radiative and mechanical power of the black hole, model how the power is transferred to the ambient medium, and how the accretion/ejection properties scale between non-nuclear stellar-mass black holes and supermassive black holes in radio galaxies. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to observe the jet-powered S26 nebula in NGC 7793 with WFC3/UVIS. One of our main objectives is to study the UV emission from the BH counterpart and the nebula: thus, we choose WFC3/UVIS because it has the highest throughput over the near-UV range. WFC3 is also slightly more sensitive than ACS in the V and R bands, and the WFC3 field of view is more than adequate for our target (size of 15 arcsec x 10 arcsec). We propose to use the following filters: F225W (which will cover nebular lines such as C II] 2325 Ang, [Ne IV] 2425 Ang, [O II] 2470 Ang, in addition to the continuum emission from the BH counterpart); F275W (which will include Mg II 2798 Ang); 12285( 2) - 12-Jul-2010 15:23:42 - [ 2] F336W (similar to U); F555W (similar to V); F814W (similar to I); F502N (covering [O III] 5007 Ang); F656N (covering H-ALPHA); F673N (covering [S II] 6716, 6731 Ang). The systemic velocity of S26 is approximately the same as the systemic velocity of its host galaxy NGC 7793, namely about 230 km/s (from NED). Therefore, the emission lines are well centred in the passbands of the respective rest-wavelength filters. We used the WFC3 Exposure Time Calculator to estimate the requested time. The optical counterpart to the X-ray core is quite bright (B = 23 mag), but we are also interested in mapping filaments and knots to a spatial resolution better than 0.4 arcsec, down to brightnesses of about 24 mag/square-arcsec, and to determine the brightness and colour of nearby stars of spectral type B4 or earlier (B <~ 25 mag), which give us a characteristic evolutionary timescale for the BH and its donor star. We used the H-ALPHA and He II 4686 line fluxes observed from our ground-based narrow-band observations as a guideline for the exposure time in the narrow-band WFC3 filters; they reach values of a few 10^{-15} erg/s/cm2/square-arcsec in the southern lobe and rim. We also compared those observations with what we expect for ionized gas with a temperature of 25, 000-30, 000 K and density ~ 1/cm3, at a distance of 3.9 Mpc. We estimate that about 1500 s in each filter, and about 2000 s in H-ALPHA will suffice to achieve our objectives and will at the same time suit the observational constraints and dithering strategy. The longer exposure time for H-ALPHA reflects the higher importance of a possible detection of Balmer line emission from the optical core. We propose to use the WFC3-UVIS-MOS-DITH-LINE pattern---a three-point dithering pattern to cover the chip gap as well as remove cosmic rays and bad pixels. Thus, every observation in each filter has to be split into three subexposures, which have to be longer than 340 s for a more efficient use of the observing time. Taking into account the overheads, we can fit the five broad-band observations into three orbits, and the three narrow-band observations into two more orbits. For example, in orbit 1: all three dithered exposures of filter 1 (exposure time of about 500 s each), plus the first two dithered exposures of filter 2; in orbit 2: the last dithered exposures of filter 2 plus all three dithered exposures of filter 3, plus the first dithered exposures of filter 4; etc. In total, we will use 5 HST orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- 12285( 2) - 12-Jul-2010 15:23:42 - [ 3] ------------------------------------------------------------------------------------ 12285( 2) - 12-Jul-2010 15:23:42 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC7793-S26 EXT-MEDIUM, EJECTA RA=23H57M59.9400S +/- 0.1", J2000 V = 23 +/- 0.5 Extended nebula. V~23 DEC=-32D33'20.90" +/- 0.1" refers to the point-like core. Reference Frame: Other: from radio & X-ray positions Comments: ------------------------------------------------------------------------------------------------------------------------------------ 12285( 2) - 12-Jul-2010 15:23:42 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.135 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 12285( 2) - 12-Jul-2010 15:23:42 - [ 6] 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F225W 1 479 S PATTERN 1 1 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F275W 1 479 S PATTERN 1 2 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F336W 1 502 S PATTERN 1 3 S ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F555W 1 502 S PATTERN 1 4 S ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F814W 1 504 S PATTERN 1 5 S ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F502N 1 502 S PATTERN 1 6 S ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F673N 1 503 S PATTERN 1 7 S ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC7793-S26 WFC3/UVI ACCUM UVIS1 F656N 1 712 S PATTERN 1 8 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC7793-S26 1 WFC3/UVI ACCUM UVIS1 F225W 1 none none none 1 N/A S NGC7793-S26 1 WFC3/UVI ACCUM UVIS1 F225W 2 none none none 1 N/A S NGC7793-S26 1 WFC3/UVI ACCUM UVIS1 F225W 3 none none none 1 N/A S NGC7793-S26 2 WFC3/UVI ACCUM UVIS1 F275W 1 none none none 1 N/A S NGC7793-S26 2 WFC3/UVI ACCUM UVIS1 F275W 2 none none none 1 N/A S NGC7793-S26 2 WFC3/UVI ACCUM UVIS1 F275W 3 none none none 2 N/A S 12285( 2) - 12-Jul-2010 15:23:42 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC7793-S26 3 WFC3/UVI ACCUM UVIS1 F336W 1 none none none 2 N/A S NGC7793-S26 3 WFC3/UVI ACCUM UVIS1 F336W 2 none none none 2 N/A S NGC7793-S26 3 WFC3/UVI ACCUM UVIS1 F336W 3 none none none 2 N/A S NGC7793-S26 4 WFC3/UVI ACCUM UVIS1 F555W 1 none none none 2 N/A S NGC7793-S26 4 WFC3/UVI ACCUM UVIS1 F555W 2 none none none 3 N/A S NGC7793-S26 4 WFC3/UVI ACCUM UVIS1 F555W 3 none none none 3 N/A S NGC7793-S26 5 WFC3/UVI ACCUM UVIS1 F814W 1 none none none 3 N/A S NGC7793-S26 5 WFC3/UVI ACCUM UVIS1 F814W 2 none none none 3 N/A S NGC7793-S26 5 WFC3/UVI ACCUM UVIS1 F814W 3 none none none 3 N/A S NGC7793-S26 6 WFC3/UVI ACCUM UVIS1 F502N 1 none none none 4 N/A S NGC7793-S26 6 WFC3/UVI ACCUM UVIS1 F502N 2 none none none 4 N/A S NGC7793-S26 6 WFC3/UVI ACCUM UVIS1 F502N 3 none none none 4 N/A S NGC7793-S26 7 WFC3/UVI ACCUM UVIS1 F673N 1 none none none 4 N/A S NGC7793-S26 7 WFC3/UVI ACCUM UVIS1 F673N 2 none none none 4 N/A S NGC7793-S26 7 WFC3/UVI ACCUM UVIS1 F673N 3 none none none 5 N/A S NGC7793-S26 8 WFC3/UVI ACCUM UVIS1 F656N 1 none none none 5 N/A S NGC7793-S26 8 WFC3/UVI ACCUM UVIS1 F656N 2 none none none 5 N/A S NGC7793-S26 8 WFC3/UVI ACCUM UVIS1 F656N 3 none none none 5 N/A S 12285( 2) - 12-Jul-2010 15:23:42 - [ 8] Summary Form for Proposal 12285 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2, PATTERN 1 3, PATTERN 1 4, PATTERN 1 5, PATTERN 1 6, PATTERN 1 7, PATTERN 1 8 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F225W, F275W, F336W, F502N, F555W, F656N, F673N, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC7793-S26 ------------------------------------------------------------------------------------------------------------------------------------