14176( 2) - 30-Jun-2015 16:09:36 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14176 Version: 2 Check-in Time: 30-Jun-2015 16:09:36 STScI Edit Number: 0 Title Measuring Absolute Abundances in NGC 5548 and Definitively Linking the UV and X-ray Outflows ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Gerard A. Kriss Space Telescope Science Institute Y CoI: Dr. Nahum Arav Virginia Polytechnic Institute and State N University CoI: Dr. Jelle Kaastra Space Research Organization Netherlands N CoI: Prof. Bradley M Peterson The Ohio State University N CoI: Dr. Ehud Behar Technion-Israel Institute of Technology N CoI: Dr. Stefano Bianchi Universita' degli Studi Roma Tre N CoI: Ms. Rozenn Boissay Observatoire de Geneve N CoI: Dr. Graziella Branduardi-Raymont University College London N CoI: Dr. Massimo Cappi INAF - IASF Bologna N CoI: Carter Chamberlain Virginia Polytechnic Institute and State N University CoI: Dr. Elisa Costantini Space Research Organization Netherlands N CoI: Dr. Barbara De Marco Max-Planck-Institut fur extraterrestrische N Physik CoI: Dr. Laura di Gesu Space Research Organization Netherlands N CoI: Dr. Jacobo Ebrero ESA-European Space Astronomy Centre N CoI: Dr. Shai Kaspi Tel Aviv University - Wise Observatory N CoI: Missagh Mehdipour Space Research Organization Netherlands N CoI: Dr. Stephane Paltani Observatoire de Geneve N CoI: Dr. Pierre-Olivier Petrucci Institut de Planetologie et N d'Astrophysique de Grenoble CoI: Dr. Ciro Pinto University of Cambridge N CoI: Dr. Gabriele Ponti Max-Planck-Institut fur extraterrestrische N Physik CoI: Dr. Katrien Christine Steenbrugge University of Oxford N CoI: Dr. Francesco Ursini Institut de Planetologie et N d'Astrophysique de Grenoble CoI: Ms. Megan Whewell University College London N ------------------------------------------------------------------------------------ Abstract We propose to obtain HST/COS spectra of the Seyfert 1 galaxy NGC 5548 with 9 orbits covering the Lyman lines, O VI, P V, N V, and C IV in conjunction with 60 ks of XMM-Newton time. Our observations will measure absolute abundances anchored by accurate H I column densities for both the narrow and broad UV absorption lines. These will add fidelity to our measurements of the outflowing mass flux and kinetic energy obtained in our 2013 campaign using XMM-Newton and COS, and solve discrepancies between the UV and X-ray absorbers in NGC 5548. Due to the profound influence of the new soft X-ray obscurer in NGC 5548 discovered during our 2013 campaign, simultaneous X-ray spectra are essential for determining the ionizing spectral energy distribution. Outflows from active galactic nuclei (AGN) may play a crucial role in feedback processes that control galaxy evolution, the growth of 14176( 2) - 30-Jun-2015 16:09:36 - [ 2] central black holes in galaxies, and the chemical enrichment of the surrounding environment. The high throughput and resolution (R > 12, 000) of COS at wavelengths below 1150 A make it possible to observe O VI and the Lyman lines in nearby bright AGN and link high-resolution X-ray spectroscopy of O VI and higher ions with longer-wavelength UV observations. Observations of the resonance doublets of O VI, N V, and C IV enable robust photoionization solutions as a function of outflow velocity that include the determination of absolute abundances relative to hydrogen. Observations of unsaturated Lyman lines are the only way to measure hydrogen column densities for absolute abundances. This provides crucial information on the physical conditions in AGN outflows and their chemistry. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain medium-resolution far-UV spectra of NGC 5548 using COS. Our 9-orbit allocation will be divided into 2 visits, which will be coordinated with two 30 ks observations using XMM-Newton. We will use COS and grating G130M/1096 primarily to measure absorption in the higher-order Lyman series lines Ly$\beta$, Ly$\gamma$, and Ly$\delta$, and in the high-ionization O VI 1032, 1038 resonance doublet. The R~12, 000 resolving power of the G130M/1096 grating setting fully resolves the ~100 km~s^{-1} widths of the UV absorption components in NGC 5548 (Crenshaw09). This resolution enables detailed measurements of trough profiles, optical depths, and covering factors in all the observed troughs. The far-UV flux of NGC 5548 has historically ranged from a low of 0.66e-14 erg~cm^{-2}~s^{-1}~\AA^{-1} at 1360 A, to a high of 8.6e-14 erg~cm^{-2}~s^{-1}~\AA^{-1} (Dunn06), with a mean flux of 4.4e-14 erg~cm^{-2}~s^{-1}~\AA^{-1}. A S/N of 10 per resolution element in the continuum at 1040 A suffices to measure covering fractions to a level of 10% in the absorption troughs. Using the COS ETC (v23.2.1) and the FOS QSO composite spectrum at z=0.017175 with E(B - V)=0.019 to match NGC 5548, this requires 17, 500 s of exposure time. This calculation is optimized for O VI, but we will achieve comparable S/N in Ly beta, gamma, and delta, and S/N>50 for P V. The combined coverage of Ly alpha through Ly delta will allow us to obtain the real H I column density even if Ly alpha is very heavily saturated since the optical depth ratio between Ly alpha and Ly delta is 38. We note that the high resolution afforded by COS makes our proposed observations robust to flux variations to fainter levels. The 100 km/s troughs are spanned by 4 COS resolution elements. If NGC 5548 were half as bright, we could bin our spectrum up by a factor of two and still oversample the absorption troughs at the same S/N. We will also make observations using the same G130M and G160M configurations we used in the 2014 reverberation campaign on NGC 5548 (HST PID 13330), in order to observe the longer wavelength absorption troughs that are not covered by G130M/1096. These include N V, Si II, Si III*, Si IV, C II, C III*, C IV, and Al II. All these lines are seen in the COS 2013 and 2014 data and are crucial for deriving a complete ionization solution of the outflow, which is necessary for absolute abundance determinations. Since NGC 5548 is highly variable in ionizing flux, we need near-simultaneous observations of these grating 14176( 2) - 30-Jun-2015 16:09:36 - [ 3] configurations with our main G130M/1096 observation in order to derive the ionization equilibrium for that epoch. Our experience with the 2014 data show that 1 orbits per visit for these G130M and G160M settings will yield sufficient S/N for our analysis, even if the object dims by half. In the separate visits comprising this proposal, we do not use four grating positions (either central wavelength or FPPOS) for each grating in the individual observations so that we minimze overheads. We use two central wavelengths in each visit for G130M and G160M to make sure we span the gap between segments A and B, and we use different FPPOS positions for each of those in the two separate visits. So, across both visits we have a 4-fold diversity of grating settings for each grating. This strategy worked well in the 2014 reverberation campaign (13330). These observations pose no bright object concerns. All historical flux levels for NGC 5548 lie below the bright object limits for COS. Since NGC 5548 has been observed successfully before (see HST PIDs 12212, 13814, and 13330), there are also no surrounding field objects that are too bright. Our ETC calculations use the ETC FOS quasar spectrum redshifted to z=0.017175 with foreground extinction of E(B-V)=0.019 and normalized to the historical minimum and maximum flux at 1360 A (flam_min=0.66e-14, flam_max=8.6e-14, Dunn et al. 2006) in order to get our limiting cases: - ACQUISITION - Configuration Flux EXP time Max cts/s/pix Total rate Buffer Time COS ETC ID G130M/1291 0.66e-14 25 s 0.10 767 3076 COS.sa.715069 G130M/1291 8.60e-14 25 s 0.13 4618 510 COS.sa.715068 - EXPOSURES - Configuration Flux EXP time Max cts/s/pix Total rate Buffer Time COS ETC ID G130M/1096 8.6e-14 1000 0.08 1621 1455 COS.sp.715065 G130M/1291 8.6e-14 1000 0.13 4533 520 COS.sp.715066 G160M/1600 8.6e-14 1000 0.02 1947 1211 COS.sp.715067 XMM-Newton Observations Our HST observations will be coordinated with 2x30 ks XMM-Newton RGS, pn, MOS and OM observations near-simultaneously with the proposed HST/COS observations. NGC 5548 has >30 ks visibility for all XMM revolutions between 2015-12-20 and 2016-02-04, giving >6 weeks of scheduling opportunities during HST Cycle 23. These observations replicate the successful visits that comprised our 2013 campaign. Average background-subtracted count rates in the summer of 2013 were 0.1 cts/s in the RGS, and 4.63 cts/s for the pn. With OM, we would get excellent fluxes using all filters and the optical grism. Recent Swift observations (2015 Feb 4) show that NGC 5548 is still obscured, and with an X-ray intensity comparable to that during the summer of 2013. Two 30 ks visits scheduled on consecutive 2-day XMM orbits will ensure near simultaneity between our X-ray spectra of NGC 5548 and our two HST visits, which presumably will take place at least one day apart in order to satisfy SAA constratints. Each HST visit should overlap, or be within 1 day of the scheduled XMM observation time. ------------------------------------------------------------------------------------ 14176( 2) - 30-Jun-2015 16:09:36 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-5548 GALAXY, ACCRETION DISK, RA=14H17M59.5130S +/- 0.1", J2000 V = 13.73 +/- 0.3 4.39e-14 at 1360 A BLR, NLR, NUCLEUS, DEC=+25D08'12.45" +/- 0.1" SEYFERT Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. UV flux is the historical mean. ------------------------------------------------------------------------------------------------------------------------------------ 14176( 2) - 30-Jun-2015 16:09:36 - [ 5] Visit: 01 Visit Requirements: SCHED 100% 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-5548 COS/FUV ACQ/PEA PSA G130M 1291 1 25 S (25 KXD S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-5548 COS/FUV ACQ/PEA PSA G130M 1291 NUM-POS=5, STEP-SIZE=0.9, 1 25 S (25 KD CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-5548 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=700, FP-POS=4 1 220 S (220 G S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-5548 COS/FUV TIME-TA PSA G130M 1327 BUFFER-TIME=700, FP-POS=1 1 220 S (220 G S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-5548 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=440, FP-POS=1 1 550 S (550 G S) ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-5548 COS/FUV TIME-TA PSA G160M 1623 BUFFER-TIME=440, FP-POS=1 1 550 S (550 G S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=2 1 2705 S G (2705 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=3 1 2705 S G (2705 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=4 1 2705 S G (2705 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-5548 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD NGC-5548 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD NGC-5548 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G NGC-5548 4 COS/FUV TIME-TA PSA G130M 1327 none none none none 1 N/A G 14176( 2) - 30-Jun-2015 16:09:36 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-5548 5 COS/FUV TIME-TA PSA G160M 1600 none none none none 1 N/A G NGC-5548 6 COS/FUV TIME-TA PSA G160M 1623 none none none none 1 N/A G NGC-5548 7 COS/FUV TIME-TA PSA G130M 1096 none none none none 2 N/A G NGC-5548 8 COS/FUV TIME-TA PSA G130M 1096 none none none none 3 N/A G NGC-5548 9 COS/FUV TIME-TA PSA G130M 1096 none none none none 4 N/A G 14176( 2) - 30-Jun-2015 16:09:36 - [ 7] Visit: 02 Visit Requirements: SCHED 100% 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-5548 COS/FUV ACQ/PEA PSA G130M 1291 1 25 S (25 KXD S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-5548 COS/FUV ACQ/PEA PSA G130M 1291 NUM-POS=5, STEP-SIZE=0.9, 1 25 S (25 KD CENTER=FLUX-WT-FLR S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-5548 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=700, FP-POS=4 1 220 S (220 G S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-5548 COS/FUV TIME-TA PSA G130M 1327 BUFFER-TIME=700, FP-POS=1 1 220 S (220 G S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-5548 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=440, FP-POS=1 1 550 S (550 G S) ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-5548 COS/FUV TIME-TA PSA G160M 1623 BUFFER-TIME=440, FP-POS=1 1 550 S (550 G S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=1 1 2705 S G (2705 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=2 1 2705 S G (2705 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=3 1 2705 S G (2705 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC-5548 COS/FUV TIME-TA PSA G130M 1096 BUFFER-TIME=330, FP-POS=4 1 2705 S G (2705 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-5548 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD NGC-5548 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD NGC-5548 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G 14176( 2) - 30-Jun-2015 16:09:36 - [ 8] 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-5548 4 COS/FUV TIME-TA PSA G130M 1327 none none none none 1 N/A G NGC-5548 5 COS/FUV TIME-TA PSA G160M 1600 none none none none 1 N/A G NGC-5548 6 COS/FUV TIME-TA PSA G160M 1623 none none none none 1 N/A G NGC-5548 7 COS/FUV TIME-TA PSA G130M 1096 none none none none 2 N/A G NGC-5548 8 COS/FUV TIME-TA PSA G130M 1096 none none none none 3 N/A G NGC-5548 9 COS/FUV TIME-TA PSA G130M 1096 none none none none 4 N/A G NGC-5548 10 COS/FUV TIME-TA PSA G130M 1096 none none none none 5 N/A G 14176( 2) - 30-Jun-2015 16:09:36 - [ 9] Summary Form for Proposal 14176 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=330, BUFFER-TIME=440, BUFFER-TIME=700, CENTER=FLUX-WT-FLR, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, NUM-POS=5, STEP-SIZE=0.9 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-5548 ------------------------------------------------------------------------------------------------------------------------------------