11001( 4) - 08/31/06 12:32 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11001 Version: 4 Check-in Time: 31-Aug-2006 16:31:56 STScI Edit Number: 1 Title Fallback Debris Disks Around Neutron Stars ------------------------------------------------------------------------------------ Type Cycle Parallel Pointing Tolerance GO 15 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Deepto Chakrabarty Massachusetts Institute of Technology CoI: Dr. Zhongxiang Wang Massachusetts Institute of Technology N CoI: Dr. David L. Kaplan Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ Abstract Our Spitzer/IRAC discovery of a dusty debris disk around the young neutron star 4U 0142+61 is the first detection of a fallback disk around a neutron star. Fallback, the notion that some material from a supernova explosion could remain bound to the compact remnant, is a general prediction of core?collapse supernova models, yet until now there were few if any meaningful observational constraints on the size (or existence) of such disks. Here we propose to test the ubiquity of such disks with deep IRAC observations of two young neutron stars, each a representative of a different class of object (a rotation?powered pulsar and a radio?quiet neutron star in a supernova remnant). We will examine whether fallback disks are common to all neutron stars or depend on the factors that separate these classes. Our proposed observations will pave the way for future surveys and in? depth investigations of individual objects. ------------------------------------------------------------------------------------ 11001( 4) - 08/31/06 12:32 - [ 2] Observations Description ------------------------ With HST, we choose to use ACS/WFC with the i' filter in the optical and NICMOS/Nic2 with the F160W filter (approximately H-band) in the near-IR. These will allow very deep exposures that have wavelength coverage to complement the Spitzer observations. We used a visual extinction A_V=1.6 for exposure-time calculations based on the column density inferred from the X-ray. Using the ACS imaging ETC, we find that we will need 150 min of HST time (3 orbits, with a visibility time of 53 min per orbit) to reach the desired level of i'=27.5 mag with S/N=5. With ACS, we will use only a single WFC chip for a 100x200 arcsec field-of-view; this will allow us to avoid the V=9.7 star HD 70745. Given that the WFC is only marginally sampled, we will use four dithered exposures of 9 min in each orbit for spatial sampling and psf reconstruction. Using the NICMOS imaging ETC, we find that we need 285 min on-source (6 orbits) to reach H=25.3 mag with S/N=5. (Both of these include instrumental overheads). We will use MULTIACCUM readout with Step=16, Nsamp=25, a 8-point spiral dither and 304-s exposures to make sure that we achieve full spatial sampling and can correctly measure the background. The full HST request is then 9 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11001( 4) - 08/31/06 12:32 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ0822.0- STAR, PULSAR, NEUTRON RA=08H21M58.2000S +/- 0.1", J2000 V = 30.0 4300 STAR DEC=-43D00'22.00" +/- 0.1" Reference Frame: ICRS 11001( 4) - 08/31/06 12:32 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type NIC-SPIRAL-DITH Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 1.537 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 11001( 4) - 08/31/06 12:32 - [ 5] Visit: 01 Visit Priority: 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 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF PATTERN 1 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF POS TARG 1, 0; PATTERN 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF POS TARG 0, 1; PATTERN 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF POS TARG 1, 1; PATTERN 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF POS TARG -1, 0; PATTERN 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 RXJ0822.0-4 NIC2 MULTIAC NIC2 F160W NSAMP=12,SAMP-SEQ=SPARS128, 1 DEF POS TARG 0,-1; PATTERN 1 300 CUM CAMERA-FOCUS=DEF,OFFSET=SAM 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 | ------------------------------------------------------------------------------------------------------------------------------------ RXJ0822.0-4300 1 NIC2 MULTIAC NIC2 F160W 1 none none none 1 N/A CUM RXJ0822.0-4300 1 NIC2 MULTIAC NIC2 F160W 2 none none none 1 N/A CUM RXJ0822.0-4300 2 NIC2 MULTIAC NIC2 F160W 1 none none none 2 N/A CUM RXJ0822.0-4300 2 NIC2 MULTIAC NIC2 F160W 2 none none none 2 N/A CUM RXJ0822.0-4300 3 NIC2 MULTIAC NIC2 F160W 1 none none none 3 N/A CUM RXJ0822.0-4300 3 NIC2 MULTIAC NIC2 F160W 2 none none none 3 N/A CUM RXJ0822.0-4300 4 NIC2 MULTIAC NIC2 F160W 1 none none none 4 N/A CUM RXJ0822.0-4300 4 NIC2 MULTIAC NIC2 F160W 2 none none none 4 N/A CUM 11001( 4) - 08/31/06 12:32 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ RXJ0822.0-4300 5 NIC2 MULTIAC NIC2 F160W 1 none none none 5 N/A CUM RXJ0822.0-4300 5 NIC2 MULTIAC NIC2 F160W 2 none none none 5 N/A CUM RXJ0822.0-4300 6 NIC2 MULTIAC NIC2 F160W 1 none none none 6 N/A CUM RXJ0822.0-4300 6 NIC2 MULTIAC NIC2 F160W 2 none none none 6 N/A CUM 11001( 4) - 08/31/06 12:32 - [ 7] Visit: 02 Visit Priority: Visit Requirements: ORIENT 170.0D TO 225.0 D; ORIENT 350.0D TO 40.0 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ0822.0-4 ACS/WFC ACCUM WFC1 F775W CR-SPLIT=NO 1 500 S PATTERN 2 1 300 see below ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ0822.0-4 ACS/WFC ACCUM WFC1 F775W CR-SPLIT=NO 1 500 S POS TARG 1, 0; PATTERN 2 300 see below 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 RXJ0822.0-4 ACS/WFC ACCUM WFC1 F775W CR-SPLIT=NO 1 500 S POS TARG 0, 1; PATTERN 2 300 see below 3 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ RXJ0822.0-4300 1 ACS/WFC ACCUM WFC1 F775W 1 none none none 1 527.0 S RXJ0822.0-4300 1 ACS/WFC ACCUM WFC1 F775W 2 none none none 1 527.0 S RXJ0822.0-4300 1 ACS/WFC ACCUM WFC1 F775W 3 none none none 1 527.0 S RXJ0822.0-4300 1 ACS/WFC ACCUM WFC1 F775W 4 none none none 1 527.0 S RXJ0822.0-4300 2 ACS/WFC ACCUM WFC1 F775W 1 none none none 2 547.0 S RXJ0822.0-4300 2 ACS/WFC ACCUM WFC1 F775W 2 none none none 2 547.0 S RXJ0822.0-4300 2 ACS/WFC ACCUM WFC1 F775W 3 none none none 2 547.0 S RXJ0822.0-4300 2 ACS/WFC ACCUM WFC1 F775W 4 none none none 2 547.0 S RXJ0822.0-4300 3 ACS/WFC ACCUM WFC1 F775W 1 none none none 3 552.0 S RXJ0822.0-4300 3 ACS/WFC ACCUM WFC1 F775W 2 none none none 3 552.0 S RXJ0822.0-4300 3 ACS/WFC ACCUM WFC1 F775W 3 none none none 3 552.0 S RXJ0822.0-4300 3 ACS/WFC ACCUM WFC1 F775W 4 none none none 3 552.0 S 11001( 4) - 08/31/06 12:32 - [ 8] Summary Form for Proposal 11001 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures NIC2 WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12 SAMP-SEQ=SPARS128 CAMERA-FOCUS=DEF OFFSET=SAM CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1; POS TARG 1, 0; PATTERN 1 2; POS TARG 0, 1; PATTERN 1 3; POS TARG 1, 1; PATTERN 1 4; POS TARG -1, 0; PATTERN 1 5; POS TARG 0,-1; PATTERN 1 6; ORIENT 170.0D TO 225.0 D; ORIENT 350.0D TO 40.0 D; PATTERN 2 1; PATTERN 2 2; PATTERN 2 3; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W F775W ------------------------------------------------------------------------------------------------------------------------------------ Target Names RXJ0822.0-4300 ------------------------------------------------------------------------------------------------------------------------------------