13304( 7) - 01-Apr-2014 13:49:58 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13304 Version: 7 Check-in Time: 01-Apr-2014 13:49:58 STScI Edit Number: 3 Title Mysterious ionization in cooling flow filaments: a test with deep COS FUV spectroscopy ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Grant R. Tremblay European Southern Observatory - Germany Y CoI: Dr. Stefi A. Baum Rochester Institute of Technology N CoI: Dr. Christopher P. O'Dea Rochester Institute of Technology N CoI: Dr. Rebecca E. A. Canning Stanford University N CoI: Dr. Tracy Clarke Naval Research Laboratory N CoI: Dr. Francoise Combes Observatoire de Paris N CoI: Dr. Megan Donahue Michigan State University N CoI: Dr. Alastair C. Edge University of Durham N CoI: Dr. Eiichi Egami University of Arizona N CoI: Prof. Andrew C. Fabian University of Cambridge N CoI: Dr. Gary J. Ferland University of Kentucky N CoI: Dr. Roderick M. Johnstone University of Cambridge N CoI: Dr. Brian R. McNamara University of Waterloo N CoI: Dr. Rupal Mittal Rochester Institute of Technology N CoI: Dr. Raymond Oonk Stichting Astronomisch Onderzoek in N Nederland (ASTRON) CoI: Dr. Helen R Russell University of Waterloo N CoI: Dr. Philippe Salome Observatoire de Paris N CoI: Dr. Craig L. Sarazin The University of Virginia N CoI: Prof. Mark Voit Michigan State University N CoI: Dr. Michael W. Wise Stichting Astronomisch Onderzoek in N Nederland (ASTRON) ------------------------------------------------------------------------------------ Abstract The Cosmic Origins Spectrograph is capable of unraveling a two decade old mystery regarding the filamentary emission line nebulae found in the brightest cluster galaxies (BCGs) of cool core (CC) clusters. These kpc-scale filaments are characterized by elevated H-alpha luminosities and puzzling ionization states that cannot be accounted for by recombination or photionization alone, and are instead excited by an unknown ionization mechanism. The most hotly debated proposed solutions invoke thermal conduction, shocks, or cosmic-ray heating, but progress toward consensus awaits unambiguous spectral discriminants between these models that can only be found in the FUV. We propose deep (9 orbit), off-nuclear observations of two strategically selected BCGs in well-studied cool core clusters with cross-spectrum archival datasets. We also propose a shorter (5 orbit) on-nuclear observation for one of our targets to assess possible AGN contributions to the spectra. These proposed observations represent critical tests that can unambiguously discriminate between the various candidate ionziation models. Constraining the mechanisms by which CC BCG filaments are excited remains one of the most important roadblocks to a better understanding of cooling from hot ambient medium to cold star forming clouds and filaments, a process important for both galaxy and black hole growth. It is therefore important that, before HST ends its mission and we lose FUV 13304( 7) - 01-Apr-2014 13:49:58 - [ 2] capability, we advance our understanding of this decades old mystery. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain deep COS FUV-mode spectroscopy of Abell 2597 (z=0.08) and ZwCl 3146 (z=0.29) with the G140L grating, tuned to a central wavelength of 1280 angstroms. Our goal is to go very deep (9 orbits, roughly 25 ksec) on the off-nuclear filaments in both of these targets. Additionally, we will take a shallower (5 orbit, ~15 ksec) observation of the A2597 nucleus (to assess possible AGN contribution to the spectra). Integration times have been estimated with the COS spectroscopic ETC using a conservative range of surface brightnessess whose median is centered on an inferred C I surface brightness of 1e-16 ersgs/sec/cm2/arcsec2. The ETC suggests that we will reach an SNR of >~ 1 (per 0.08 angstrom pixel wavelength bin) for a 25 ksec exposure using the faintest, most conservative line and continuum cases for both targets. The filaments will fill the COS aperture, spreading over 100 wavelength bins for a combined effective SNR of >8 (on the conservative end), allowing flux measurements to 15% accuracy. Binning over 50 angstroms will allow us to detect the continuum and the lines of interest at an SNR of ~10, even after accounting for vignetting and attenuation due to declining effective area. At shorter wavelengths, we will likely detect more counts allowing for fine-grained definition of the continuum near the short wavelength turnover. After accounting for overheads, we can achieve this 25 ksec exposure time in 9 orbits for each off-nuclear pointing. We further estimate that 5 orbits will be required for the on-nucleus (i.e. significantly brighter) pointing in A2597. We estimate that similar SNR will be reached for both lines and continuum for this on-nucleus observation. With this observing strategy, contaminating geocoronal Ly-alpha emission will fall in the FUV detector gap between segments B and A and will not be recorded in the data. We therefore do not require umbral shadow observations and are not subject to special scheduling constraints for any of our two targets. Our observations are all well below the brightness limits for COS. We will observe using the recommended TIME-TAG mode to allow temporal sampling, improved thermal correction, and exclusion of poor quality data from the final co-addition. All four FP-POS settings will be used, as recommended. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13304( 7) - 01-Apr-2014 13:49:58 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ABELL-2597-N CLUSTER OF GALAXIES, RA=23H25M19.6700S +/- 0.1", J2000 V = 16.6 UCLEUS BCM, CONDUCTION FRONT, DEC=-12D07'25.79" +/- 0.1" COOLING FLOW, EMISSION LINE NEBULA, NUCLEUS Reference Frame: ICRS Comments: The listed coorindates are for the desired center of the 4"x4" ACQ/IMAGE search field. We would like the COS Primary Science Aperture to be centered around the brightest region within this field. ------------------------------------------------------------------------------------------------------------------------------------ 2 ABELL-2597-F CLUSTER OF GALAXIES, RA-OFF=0.168S, DEC-OFF=3.88", J2000 V = 16.6 ILAMENT BCM, CONDUCTION FRONT, FROM 1 COOLING FLOW, EMISSION LINE NEBULA, FILAMENT Comments: This is an offset calculated from the brightest FUV knot cospatial with the A2597 nucleus. We wish to acquire on this knot, and then offset to the filament. Positioning of this offset intentionally avoids the rim of likely shocked gas at the northern edge of the radio lobe. ------------------------------------------------------------------------------------------------------------------------------------ 3 ZWCL-3146-FI CLUSTER OF GALAXIES, RA=10H23M39.7890S +/- 0.1", J2000 V = 20.0 LAMENT BCM, CONDUCTION FRONT, DEC=+04D11'8.86" +/- 0.1" COOLING FLOW, EMISSION LINE NEBULA, FILAMENT Reference Frame: ICRS Comments: The listed coorindates are for the desired center of the 4"x4" ACQ/IMAGE search field. We would like the COS Primary Science Aperture to be centered around the brightest region within this field. This pointing intentionally avoids the nucleus (location of the unresolved radio source). ------------------------------------------------------------------------------------------------------------------------------------ 13304( 7) - 01-Apr-2014 13:49:58 - [ 4] 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 ABELL-2597- COS/NUV ACQ/IMA PSA MIRRORA 1 200 S (200 NUCLEUS GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 FP-POS=1, EXTENDED=YES, 1 2140 S NUCLEUS G FLASH=YES, BUFFER-TIME=2040 (2140 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 FP-POS=1, EXTENDED=YES, 1 2953 S NUCLEUS G FLASH=YES, BUFFER-TIME=2853 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 FP-POS=2, EXTENDED=YES, 1 2953 S NUCLEUS G FLASH=YES, BUFFER-TIME=2853 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 FP-POS=3, EXTENDED=YES, 1 2953 S NUCLEUS G FLASH=YES, BUFFER-TIME=2853 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 FP-POS=4, EXTENDED=YES, 1 2953 S NUCLEUS G FLASH=YES, BUFFER-TIME=2853 (2953 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 | ------------------------------------------------------------------------------------------------------------------------------------ ABELL-2597-NUCLEUS 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ABELL-2597-NUCLEUS 2 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A G ABELL-2597-NUCLEUS 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G ABELL-2597-NUCLEUS 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G ABELL-2597-NUCLEUS 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 4 N/A G ABELL-2597-NUCLEUS 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 5 N/A G 13304( 7) - 01-Apr-2014 13:49:58 - [ 5] Visit: 02 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 ABELL-2597- COS/NUV ACQ/IMA PSA MIRRORA 1 200 S (200 NUCLEUS GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2140 S FILAMENT G BUFFER-TIME=2040, FP-POS=1 (2140 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=1 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=2 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=2 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=3 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=3 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=3 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=4 (2953 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 ABELL-2597- COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2953 S FILAMENT G BUFFER-TIME=2853, FP-POS=4 (2953 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 | ------------------------------------------------------------------------------------------------------------------------------------ ABELL-2597-NUCLEUS 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ABELL-2597-FILAMENT 2 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A G ABELL-2597-FILAMENT 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 N/A G 13304( 7) - 01-Apr-2014 13:49:58 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ABELL-2597-FILAMENT 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 N/A G ABELL-2597-FILAMENT 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 4 N/A G ABELL-2597-FILAMENT 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 5 N/A G ABELL-2597-FILAMENT 7 COS/FUV TIME-TA PSA G140L 1280 none none none none 6 N/A G ABELL-2597-FILAMENT 8 COS/FUV TIME-TA PSA G140L 1280 none none none none 7 N/A G ABELL-2597-FILAMENT 9 COS/FUV TIME-TA PSA G140L 1280 none none none none 8 N/A G ABELL-2597-FILAMENT 10 COS/FUV TIME-TA PSA G140L 1280 none none none none 9 N/A G 13304( 7) - 01-Apr-2014 13:49:58 - [ 7] Visit: 03 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 ZWCL-3146-F COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 GS ACQ SCENARIO BASE1B3 ILAMENT GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 1734 S ILAMENT G BUFFER-TIME=1634, FP-POS=1 (1734 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=1 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=2 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=2 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=3 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=3 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=3 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=4 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 ZWCL-3146-F COS/FUV TIME-TA PSA G140L 1280 EXTENDED=YES, FLASH=YES, 1 2945 S ILAMENT G BUFFER-TIME=2845, FP-POS=4 see below (2943 S) ------------------------------------------------------------------------------------------------------------------------------------ 13304( 7) - 01-Apr-2014 13:49:58 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ZWCL-3146-FILAMENT 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ZWCL-3146-FILAMENT 2 COS/FUV TIME-TA PSA G140L 1280 none none none none 1 N/A G ZWCL-3146-FILAMENT 3 COS/FUV TIME-TA PSA G140L 1280 none none none none 2 2943.0 S G ZWCL-3146-FILAMENT 4 COS/FUV TIME-TA PSA G140L 1280 none none none none 3 2943.0 S G ZWCL-3146-FILAMENT 5 COS/FUV TIME-TA PSA G140L 1280 none none none none 4 2943.0 S G ZWCL-3146-FILAMENT 6 COS/FUV TIME-TA PSA G140L 1280 none none none none 5 2943.0 S G ZWCL-3146-FILAMENT 7 COS/FUV TIME-TA PSA G140L 1280 none none none none 6 2943.0 S G ZWCL-3146-FILAMENT 8 COS/FUV TIME-TA PSA G140L 1280 none none none none 7 2943.0 S G ZWCL-3146-FILAMENT 9 COS/FUV TIME-TA PSA G140L 1280 none none none none 8 2943.0 S G ZWCL-3146-FILAMENT 10 COS/FUV TIME-TA PSA G140L 1280 none none none none 9 2943.0 S G 13304( 7) - 01-Apr-2014 13:49:58 - [ 9] Summary Form for Proposal 13304 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1634, BUFFER-TIME=2040, BUFFER-TIME=2845, BUFFER-TIME=2853, EXTENDED=YES, FLASH=YES, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names ABELL-2597-FILAMENT, ABELL-2597-NUCLEUS, ZWCL-3146-FILAMENT ------------------------------------------------------------------------------------------------------------------------------------