13320( 2) - 21-Jun-2013 16:56:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13320 Version: 2 Check-in Time: 21-Jun-2013 16:56:50 STScI Edit Number: 0 Title Unveiling the nature of ultraluminous X-ray sources via UV spectroscopy ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Fabien Grise Instituto de Astrofisica de Canarias Y CoI: Dr. Philip Kaaret University of Iowa N CoI: Prof. Stephane Corbel Commissariat a l'Energie Atomique (CEA) N CoI: Dr. David Cseh Radboud Universiteit Nijmegen N CoI: Dr. Hua Feng Tsinghua University N CoI: Dr. Lian Tao Tsinghua University N ------------------------------------------------------------------------------------ Abstract Our recent HST/Chandra study of the ultraluminous X-ray source (ULX) in NGC 5408 showed that the X-ray/UV/optical/NIR spectral energy distribution (SED) is consistent with emission from an irradiated accretion disk, while the UV/optical/NIR SED alone can also be explained as a B0I supergiant star. If the accretion disk dominates in the far-UV, then we expect to see a wealth of spectral lines features in the far-UV spectrum. If, instead, the far-UV light arises from an early B supergiant, we expect to see UV lines with strong P-Cygni profiles. To determine the physical origin of the UV/optical/NIR emission, we propose to take a deep look at the far-UV spectrum of the ULX using the unique capabilities of the Cosmic Origins Spectrograph. The spectrum obtained will definitively distinguish between an irradiated accretion disk and a supergiant companion star. Detection of UV lines is likely one of the only direct ways to constrain the physical nature of ultraluminous X-ray sources. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program consists of two COS observations (4 orbits each), to be carried out with the G140L spectral element at the central wavelength 1105 A. As recommended, we will be using all four FP-POS offsets. Given the well-known position of the target, the acquisition will be done using the ACQ/IMAGE mode. Real Time Justification ----------------------- To look for variability, the second observation should be carried out at least 5 days after the first observation has been executed. Calibration Justification ------------------------- Additional Comments ------------------- 13320( 2) - 21-Jun-2013 16:56:50 - [ 2] ------------------------------------------------------------------------------------ 13320( 2) - 21-Jun-2013 16:56:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5408X-1 UNIDENTIFIED, ACCRETION RA=14H03M19.6200S +/- 0.2", J2000 V = 22.4 +/- 0.1 m_F225W (VegaMag) = DISK, OPTICAL EMITTER, DEC=-41D22'58.50" +/- 0.2" 20.05 +/- 0.1 ; F_F225W = 4.05 +/- 0.25 ULTRAVIOLET EMITTER, 10^-17 erg/s/cm^2/A X-RAY EMITTER Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 13320( 2) - 21-Jun-2013 16:56:50 - [ 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 NGC5408X-1 COS/NUV ACQ/IMA PSA MIRRORA 1 200 S (200 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5408X-1 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=8600, 1 2750 S G FLASH=YES, SEGMENT=A see below (11408 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC5408X-1 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 2267.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 2 2 3047.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 3 3 3047.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 4 4 3047.0 S G 13320( 2) - 21-Jun-2013 16:56:50 - [ 5] Visit: 02 Visit Requirements: AFTER 01 BY 5 D TO 60 D 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 NGC5408X-1 COS/NUV ACQ/IMA PSA MIRRORA 1 200 S (200 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5408X-1 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=8600, 1 2750 S G FLASH=YES, SEGMENT=A see below (11408 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC5408X-1 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 2267.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 2 2 3047.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 3 3 3047.0 S G NGC5408X-1 2 COS/FUV TIME-TA PSA G140L 1105 none none none 4 4 3047.0 S G 13320( 2) - 21-Jun-2013 16:56:50 - [ 6] Summary Form for Proposal 13320 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=8600, FLASH=YES, FP-POS=ALL, SEGMENT=A ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 5 D TO 60 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5408X-1 ------------------------------------------------------------------------------------------------------------------------------------