14247( 2) - 21-Jul-2015 18:36:47 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14247 Version: 2 Check-in Time: 21-Jul-2015 18:36:47 STScI Edit Number: 0 Title Confirmation of an Intermediate-Mass Black Hole in an Extragalactic Globular Cluster ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Jimmy A. Irwin University of Alabama Y CoI: Dr. Drew Reid Clausen California Institute of Technology N CoI: Prof. Steinn Sigurdsson The Pennsylvania State University N CoI: Prof. Michael Eracleous The Pennsylvania State University N ------------------------------------------------------------------------------------ Abstract The long and controversial search for black holes within globular clusters has reached the point where extragalactic globular clusters provide fertile hunting grounds for finding black holes of both stellar and intermediate-mass (IMBH) varieties. While a luminous X-ray point source within a cluster can indicate the presence of a black hole, little can generally be said of its mass without further observation. In the event that a black hole tidally disrupts a passing star in the cluster, optical/UV emission lines from the X-ray-illuminated debris can not only demonstrate the existence of a black hole in the cluster, but can also provide powerful constraints on the mass of the black hole, the composition of the disrupted star, and even the time since the tidal disruption event took place. We propose an HST COS G140L UV spectrum of a globular cluster within the Fornax elliptical galaxy NGC1399 that exhibits unusual optical [N II] and [O III] forbidden emission lines that are believed to result from such a tidal disruption event by a ~100 solar mass black hole. Our models predict that the ratios of the expected emission lines from carbon, nitrogen, and oxygen that should be present in the UV spectrum of the source will be able to distinguish a stellar-mass black hole from an IMBH as the disruptor, as well as determine the nature of the disrupted star. If the mass of the black hole is constrained to be in excess of 100 solar masses, this would provide one of the most compelling pieces of evidence to date that IMBHs exist within globular clusters. ------------------------------------------------------------------------------------ Observations Description ------------------------ For the position of the source, we registered an HST/ACS B-band image of NGC1399 to the ICRS coordinate system using matched USNOB-1 stars that fell within the field of view. The coordinates of our source agreed well with the position found for the source by two other independent studies of NGC1399's globular cluster system to within 0.1": Paolillo et al. (2011) - who registered an HST/ACS/606W image to USNOB-1 stars with quoted positional accuracies of 0.2", and Kim et al. (2013) - who registered ground-based imaging to USNOB-1 star positions and also obtained an absolute astrometry accuracy of 0.2". Given the agreement of these three matching studies, we are confident that the coordinates of our source are accurate to 0.2" in RA and Dec. Our source has a magnitude of 23.8 in Johnson U (Kim et al. 2013), so using the 14247( 2) - 21-Jul-2015 18:36:47 - [ 2] "Elliptical galaxy with strong UV upturn" template of the COS ETC (since a metal-rich globular cluster would have a similar stellar population), we calculate that an exposure of 400 seconds will detect the source at S/N=25 for acquisition purposes. This will be a lower limit, since we did not include the flux from any emission lines that might be present in the NUV spectrum. We kept all visits to 2-3 orbits each as requested for Cycle 23. All four FP-POS steps were used during each visit, although they were judiciously spaced throughout the 2-3 orbit period to reduce unnecessary overhead. ------------------------------------------------------------------------------------ 14247( 2) - 21-Jul-2015 18:36:47 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CXO-J033831. EXT-CLUSTER, EMISSION RA=03H38M31.8100S +/- 0.2", J2000 V = 22.4 B=23.2 U = 23.8 8-352604 LINE NEBULA, GLOBULAR DEC=-35D26'4.50" +/- 0.2" CLUSTER Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 14247( 2) - 21-Jul-2015 18:36:47 - [ 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 CXO-J033831 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 .8-352604 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=1, BUFFER-TIME=1808 1 1808 S .8-352604 G (1808 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=2, BUFFER-TIME=1708 1 1808 S .8-352604 G (1808 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=1068 1 1068 S .8-352604 G (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=968 1 1068 S .8-352604 G (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=4, BUFFER-TIME=1808 1 1808 S .8-352604 G (1808 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 | ------------------------------------------------------------------------------------------------------------------------------------ CXO-J033831.8-35260 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 4 GE CXO-J033831.8-35260 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 N/A 4 G CXO-J033831.8-35260 6 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 N/A 4 G 14247( 2) - 21-Jul-2015 18:36:47 - [ 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 CXO-J033831 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 .8-352604 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=1, BUFFER-TIME=1808 1 1808 S .8-352604 G (1808 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=2, BUFFER-TIME=1708 1 1808 S .8-352604 G (1808 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=1068 1 1068 S .8-352604 G (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=968 1 1068 S .8-352604 G (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=4, BUFFER-TIME=1808 1 1808 S .8-352604 G (1808 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 | ------------------------------------------------------------------------------------------------------------------------------------ CXO-J033831.8-35260 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 4 GE CXO-J033831.8-35260 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 N/A 4 G CXO-J033831.8-35260 6 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 N/A 4 G 14247( 2) - 21-Jul-2015 18:36:47 - [ 6] 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 CXO-J033831 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 .8-352604 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=1, BUFFER-TIME=746 1 846 S (846 .8-352604 G S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=2, BUFFER-TIME=846 1 846 S (846 .8-352604 G S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=1338 1 1438 S .8-352604 G (1438 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=4, BUFFER-TIME=1438 1 1438 S .8-352604 G (1438 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 | ------------------------------------------------------------------------------------------------------------------------------------ CXO-J033831.8-35260 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 4 GE CXO-J033831.8-35260 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G 14247( 2) - 21-Jul-2015 18:36:47 - [ 7] Visit: 04 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 CXO-J033831 COS/NUV ACQ/IMA PSA MIRRORA 1 400 S (400 .8-352604 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=1, BUFFER-TIME=746 1 846 S (846 .8-352604 G S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=2, BUFFER-TIME=846 1 846 S (846 .8-352604 G S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=3, BUFFER-TIME=1338 1 1438 S .8-352604 G (1438 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CXO-J033831 COS/FUV TIME-TA PSA G140L 1105 FP-POS=4, BUFFER-TIME=1438 1 1438 S .8-352604 G (1438 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 | ------------------------------------------------------------------------------------------------------------------------------------ CXO-J033831.8-35260 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 4 GE CXO-J033831.8-35260 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A 4 G CXO-J033831.8-35260 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G CXO-J033831.8-35260 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A 4 G 14247( 2) - 21-Jul-2015 18:36:47 - [ 8] Summary Form for Proposal 14247 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1068, BUFFER-TIME=1338, BUFFER-TIME=1438, BUFFER-TIME=1708, BUFFER-TIME=1808, BUFFER-TIME=746, BUFFER-TIME=846, BUFFER-TIME=968, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names CXO-J033831.8-352604 ------------------------------------------------------------------------------------------------------------------------------------