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SCIENTIFIC GOALS INSTRUMENT DESIGN OBSERVING MODES PERFORMANCE ESTIMATION

THE SPIRE INSTRUMENT. Matt Griffin Queen Mary and Westfield College, London, UK Bruce Swinyard Rutherford Appleton Laboratory, Oxfordshire, UK Laurent Vigroux Service d’Astrophysique, Saclay, France + the SPIRE Consortium (Canada, Italy, France, Spain, Sweden, UK, USA). SCIENTIFIC GOALS

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SCIENTIFIC GOALS INSTRUMENT DESIGN OBSERVING MODES PERFORMANCE ESTIMATION

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  1. THE SPIRE INSTRUMENT Matt Griffin Queen Mary and Westfield College, London, UK Bruce SwinyardRutherford Appleton Laboratory, Oxfordshire, UK Laurent VigrouxService d’Astrophysique, Saclay, France + the SPIRE Consortium (Canada, Italy, France, Spain, Sweden, UK, USA) • SCIENTIFIC GOALS • INSTRUMENT DESIGN • OBSERVING MODES • PERFORMANCE ESTIMATION Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  2. The SPIRE Consortium • Caltech/Jet Propulsion Laboratory, Pasadena, USA• CEA Service d’Astrophysique, Saclay, France• Institut d’Astrophysique Spatiale, Orsay, France • Imperial College, London, UK• Instituto de Astrofisica de Canarias, Tenerife, Spain• Istituto di Fisica dello Spazio Interplanetario, Rome, Italy • Laboratoire d’Astronomie Spatiale, Marseille, France• Mullard Space Science Laboratory, Surrey, UK• NASA Goddard Space Flight Center, Maryland, USA• Observatoire de Paris, Meudon, Paris• Queen Mary and Westfield College, London, UK• UK Astronomy Technology Centre, Edinburgh, UK• Rutherford Appleton Laboratory, Oxfordshire, UK• Stockholm Observatory, Sweden• Università di Padova, Italy• University of Saskatchewan, Canada Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  3. Galaxies – normal, starburst and AGN Statistics and physics of galaxy formation in the early universe 10 1 0.1 0.01 Solar system: giant planets, comets and solid bodies Star formation and interstellar matter SPIRE Scientific Goals l (mm) 100 10 1000 Z = 0.1 1012L 0.5 1 Flux density (Jy) 3 5 l (mm) 1000 10 100 Flux density (Jy) SPIRE PACS Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  4. SPIRE Instrument Summary • 3-band imaging photometer - 250, 350, 500 mm (simultaneous) - l/Dl ~ 3 - 4 x 8 arcminute field of view - Diffraction limited beams (17, 24, 35”) • Imaging FTS- 200 - 400 mm (goal 200 - 670 mm) - > 2 arcminute field of view - Ds = 0.4 cm-1 (goal 0.04 cm-1) (l/Dl ~ 20 - 100 (1000) at 250 mm)• Design features- Sensitivity limited by thermal emission from the telescope (80 K; e = 4%) - 3He cooled detector arrays (0.3 K) - Feedhorn-coupled spider web NTD bolometers - Minimal use of mechanisms - Beam steering mirror; FTS mirror drive Cryostat lid Baffle PACS SPIRE HIFI FIRST optical bench Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  5. Mirrors SPIRE FPU Optics FPU Structure Baffles BSM Filters, Beam dividers, Dichroics SMEC Phot. Cal. Source Thermometers FTS Cal. Source Cooler Shutter Detector Arrays (0.3 K) S1 S2 P2 RF RF RF RF RF RF P3 P1 Filter Filter Filter Filter Filter Filter JFET/RF filter Boxes FTBp FTBs Optical Bench Cryostat Wall Detector Control Unit (DCU) FPU Control Unit (FCU) Warm Interconnect Harness (FSWIH) SPIRE Warm Electronics on SVM Digital Processing Unit (DPU) SpacecraftElectronics Spacecraft Command and Data Management System (CDMS) Spacecraft Power Distribution Unit SPIRE Block Diagram Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  6. SPIRE FPU Photometer Spectrometer 690 mm Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  7. Beam steering mirror 2-K cold stop Dichroics and arrays M4 M6 M8 M3 M5 M9 M7 FIRST focal surface Offner relay Photometer Layout and Optics 2-K box 3He cooler Baffles Beam steering sirror RF filter modules M4 M9 M7 M5 M3 SPIRE optical bench (4 K) Detector arraymodules Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  8. Dichroics DetectorArray Light-tightseal for 0.3-K thermal strap Cold pupil stop at box entrance Final mirror of Offner relay Photometer 2-K Box and 300-mK Straps Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  9. FTS Layout and Optics Fore-optics shared with photometer 4-Kbox 2-Kbox Telescope input port Output port Baffle Beam divider Calibrator input port Detector arraymodules Intensity beam dividers Output port Mirrormechanism Calibrator Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  10. Prototype Broadband Beam Divider 2RTR2 + T2 Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  11. FTS Mechanism Design • Double parallelogram with toothless gear • Moiré fringe position measurement system (0.1 mm accuracy) • Corner cube reflectors compensate for tilt and rotation • - 0.3 -- +3.5 cm movement Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  12. 20 nV Hz-1/2 System noise voltage 20 nV Hz-1/2 20 nV Hz-1/2 10 0.01 0.1 1 Frequency (Hz) Bolometer array wafer NTD Ge Bolometer Arrays (Caltech/JPL) NTD Ge thermometer • NEP ~ 3 x 10-17 W Hz-1/2• 100-K Si JFET readout • 1/f noise knee < 100 mHz Spider-web absorbing grid Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  13. Beam FWHM = l/D JCMT-SCUBA 450 mm array Sky Sampling with Feedhorn Arrays Full sampling of the image requires scanning or “jiggling” of the telescope pointing FWHM beams on the sky don’t overlap Feedhorns adjacentin the focal plane Beam separation = 2l/D 16 pointings needed for fully-sampled image Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  14. Overlapping beams Detector Arrays (2Fl Feedhorns) Photometer Spectrometer 500 m 43 detectors 350 m 88 detectors 250 m 139 detectors 200-300 m 37 detectors 45 mm 300-670 m 19 detectors 23 mm Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  15. Bolometer Array Module Filter covering feedhorn array Dummy array Connection to 3He fridge 300-mK stage 2 K mounting flange Readout cable attachment Kevlar suspension SPIRE array module demonstrator 2-K stage and interface to SPIRE 2-K box Ribbon Cables Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  16. Total transmission 350 mm Filtering Scheme Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  17. 1 10-3 10-7 10-11 10-15 10-19 10-23 10 Filter Out-of-Band Rejection Requirement Transmission 100 1,000 100,000 10,000 Wavenumber cm-1 Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  18. Photometer Observing Modes • Point source photometry: - Beam steering mirror chops 125” between overlapping sets of detectors - Seven-point jiggle can be done if desired • Field mapping: - Beam steering mirror chops up to 4’ and performs 64-point “jiggle” - Available fov = 4’ x 4’ • Scan mapping: - Beam steering mirror not operated - Telescope drift scanning at up to 60”/second - Scan angle wrt array axis set to give full spatial sampling Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  19. B A Y Z X Point Source Photometry • Telescope pointing fixed • Chopping in Y-direction between A and B (126”) • Simultaneous observation in the three bands with two sets of co-aligned detectors • Chop without jiggling is OK if the pointing is accurate enough (~ 1.5”) Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  20. 250 mm 20 16 350 mm  Signal loss (%) 12 8 500 mm 4 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Pointing offset (arcsec.) 7-point Jiggle Map • Chopping 126” • 7-point jiggle pattern• Angular step  ~ 4 - 6 arcseconds (> pointing or positional error)• Total flux and position can be fitted• Compared to single accurately pointed observation, S/N for same total integration time is only degraded by ~ 20% at 250 mm ~ 13% at 350 mm ~ 6% at 500 mm Signal loss for blind pointing Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  21. ± 2 arcmin maximum. Y Z X Field Mapping • Telescope pointing fixed or in raster mode • Chopping up to 4 arcmin amplitude in Y direction • 64-point “jiggle” pattern for full spatial sampling Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  22. 14.5o 14.5o Y Z X Scan Mapping • Telescope in line scanning mode • Scan rate ~ 20-30”/sec.) • Map of large area is built up from overlapping parallel scans • Most efficient mode for large-area surveys Scan directions for instantaneous full sampling Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  23. Relative mapping speed 1/f knee frequency (Hz) Simulations of scanning without modulation: need for good 1/f stability 500 mm 250 mm Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  24. 200-300 m 37 detectors 300-670 m 19 detectors FTS Observing Modes • Mirror scan rate = 1 mm s-1 • Signal frequency range 6 - 20 Hz • Maximum scan length = 3.5 cm (14 cm OPD) • Ds = 0.04 - 2 cm-1 by adjusting scan length• Calibrator in second port nulls telescope background • Point source spectroscopy/spectrophotometry - Telescope pointing fixed - Background characterised by adjacent pixels • Imaging spectroscopy - Beam steering mirror adjusts pointing between scans to acquire fully-sampled spectral image Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  25. 3He Cooler Evaporator (0.3 K) Sorption pump Pumping line • Cold stage temp. < 280 mK • Hold time > 46 hrs • Cycle time < 2 hrs • Average load on 4He tank < 3 mW • Heat lift > 10 mW • Gas-gap heat switches (no moving parts) Prototype cooler Gas-gap heat switch Kevlar suspension Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  26. Photometry (all bands) Flux density (mJy, 5-; 1 hr)Point source 4.0 (req.) 2.0 (goal) Map (4’x 4’) 16 (req.) 8.0 (goal) FTS: Spectroscopy 200 - 400 mm Ds = 0.04 cm-1 Line flux (W m-2 x 10-17, 5-; 1 hr) Point source 6.0 (req.) 3.0 (goal) Map 18 (req.) 9.0 (goal) FTS: Spectrophotometry 200 - 400 mm Ds = 1 cm-1 Flux density (mJy, 5-; 1 hr) Point source 200 (req.) 100 (goal) Map 600 (req.) 300 (goal) FTS sensitivity declines by factor of ~ 2 between 400 and 670 mm Estimated Instrument Sensitivity Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  27. SPIRE PACS Protostars and YSOs: Spectral Coverage and Capabilities • Unbiased surveys of nearby molecular clouds • Complete census of protostellar condensations within ~ 1 kpc • Temperature and density distributions• Total luminosities• Dust properties• Star formation rate and efficiency • Initial mass function Figure by Philippe André Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  28. 10,000 1012L Wavelength coverage of PACS and SPIRE imaging photometers Z = 0.1 1000 0.5 1 100 3 Flux density (mJy) 10 5 1 0.1 10 100 1,000 10,000 l(mm) After Guiderdoni et al. MNRAS 295, 877, 1998 High-Redshift Galaxy Surveys with FIRST • Unbiased survey of population of high-z dusty star-forming galaxies missed by current (and future) optical and near-IR surveys • Large-scale structure in the high- redshift universe • Star-formation history in galaxies at z out to 5 Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  29. 170/350 z SPIRE PACS 250/500 250/850 170/500 z Photometric Redshifts z for 5- measurement of flux density ratio with known SED Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  30. SPIRE Large-Area Survey Sensitivity Confusion limits are from the models of M. Rowan-Robinson (Ap. J., in press) Assumptions • Scan-map mode • 90% observing efficiency • 21 hrs observing/day • 25% field overlap • 75% detector yield Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  31. Survey Strategy • SPIRE confusion limit is ~ 15 - 20 mJy: reached at 5-s over the full 4 x 8 arcmin fov in < 15 minutes in 3 bands simultaneously  wide area rather than small ultra-deep surveys • Observations of smaller areas with PACS imaging photometer • Multi-wavelength survey near peak of the red-shifted SED  total luminosities; photometric redshifts estimation • Follow-up with SPIRE FTS and other instruments for physics and SEDs of brighter sources: e.g.: - SPIRE FTS can reach 1-200 mJy (5-) per spectral element with / ~ 20 in 1 hr - PACS spectrometer can detect diagnostic lines to distinguish AGN from starburst in several hours •  Example of Planck HFI Survey follow-up: - DECS: 2 ~ 14o x 14o (total ~ 400 sq. deg.) maps near ecliptic poles - Detection thresholds: (850, 545, 350) mm: (100, 220, 220) mJy - SPIRE ~ 2-3 week survey of the same area: improved positions, and sensitivity (5-s detection thresholds ~ 100 mJy) and extended spectral coverage Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

  32. Possible SPIRE Survey and Outcome • 100 sq. deg.• Confusion-limited• 1 - 200 days • DS5 s < 15 mJy 1,300 sources/sq. deg.660sources/sq. deg. 320sources/sq. deg. Source count models of M. Rowan-Robinson Toledo Symposium, The Promise of FIRST , 11 - 15 December 2000

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