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Destiny, The Dark Energy Space Telescope

Destiny, The Dark Energy Space Telescope. Science Goals & Overview. Determine the expansion history of the Universe to 1% accuracy in z = 0.1 bins over the last 10 10 yr. Constrain Dark Energy equation of state parameters w 0 to 0.05 and w a to 0.20.

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Destiny, The Dark Energy Space Telescope

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  1. Destiny, The Dark Energy Space Telescope STScI - May 8, 2008

  2. Science Goals & Overview • Determine the expansion history of the Universe to 1% accuracy in z = 0.1 bins over the last 1010 yr. • Constrain Dark Energy equation of state parameters w0 to 0.05 and wa to 0.20. • Destiny is a Stage IV dark energy program. STScI - May 8, 2008

  3. DESTINY Fact Sheet • 1.65m telescope at L2 • H2RG FPA • SN1a survey over > 3°2 • WL survey 1000°2 • NIR imaging 0.85 m < l1.7 m • Imaging Spectrograph with l/l~ 75 STScI - May 8, 2008

  4. A Brief History of Destiny • Astronomical community recognizes the potential of dark energy space probes. • NASA & DOE propose a generic Joint Dark Energy Mission • Initial Destiny concept for JDEM proposed in 2003. Wins initial concept study. LMCO & LANL partners. • NASA creates general “Beyond Einstein” program for astrophysical missions: Con-X, LISA, CMB probes, etc. Includes JDEM . • Destiny wins 1 of 3 JDEM concept studies in 2006. NRC BEPAC recommends JDEM for first BE start in 2007. • Probable JDEM call in September 2008 for 2009 start. STScI - May 8, 2008

  5. DESTINY Philosophy • Complete heritage - Well understood technology in a unique configuration. • Use the minimal instrument required • Do only in space what must be done in space - leverage ground based observations. • All spectra all the time. Complete spectro- photometric time series on all SN events. • Highly automated survey - no time critical operations. STScI - May 8, 2008

  6. PI: Tod R. Lauer (NOAO) Matthew Beasley (Colorado) Chris Burns (OCIW) Kenneth Carpenter (GSFC) Doug Clowe (Ohio U) Ian Dellantonio (Brown) Megan Donahue (MSU) Olivier Dore (Toronto) Chris Fassnacht (UC Davis) Wendy Freedman (OCIW) Chris Fryer (LANL) Peter Garnavich (notre Dame) Jay Holberg (Arizona) Aimee Hungerford (LANL) Robert Kirshner (Harvard) Lori Lubin (UC Davis) Deputy PI: Dominic Benford (GSFC) Sangeeta Malhotra (ASU) Tom Matheson (NOAO) Phillip Pinto (Arizona) Nor pirzkal (STScI) Marc Postman (STScI) James Rhoads (ASU) Yong-Seon Song (Chicago) George Sonneborn (GSFC) Sumner Starrfield (ASU) Nicholas Suntzeff (TAMU) Frank Timmes (ASU) Thomas Vestrand (LANL) Mike Warren (LANL) Rogier Windhorst (ASU) Robert Woodruff (LMCO) Ann Zabludoff (Arizona) Destiny Science Team STScI - May 8, 2008

  7. Supernovae STScI - May 8, 2008

  8. Why go to high redshifts? Dark energy can be detected at low redshift, but precise constraints on the DE Eos requires measurements over both the acceleration and deceleration epochs. Ground Space STScI - May 8, 2008

  9. NIR available only in space Crucial near-infrared observations are impossible from the ground for the required photometric accuracy • Sky is very bright in NIR: >100x brighter than in visible • Sky is not transparent in NIR: absorption due to water is very strong and extremely variable Data from Gemini Observatory & ATRAN: Lord (1992) STScI - May 8, 2008

  10. Riess et al. (2004) obtain ACS grism spectra of z ~ 1.3 SN Ia STScI - May 8, 2008

  11. ACS Grism Images of SN2002FW (z = 1.30) Riess et al. (2004) STScI - May 8, 2008

  12. Supernova Observations • Filter: locate SN & host galaxy • Dispersed mode: spectral time series • Difference & extract SN spectrophotometry STScI - May 8, 2008

  13. Supernovae Survey Schema Survey area is a contiguous Mosaic of Destiny FOVs. Orientation rolls by 90º every 3 months. Dithering will fill in chip gaps and ensure Nyquist sampling. STScI - May 8, 2008

  14. Observing Timeline for SN Survey Times and slews are not shown to scale STScI - May 8, 2008

  15. Preliminary Operations Times for SN Survey Times and slews are not shown to scale STScI - May 8, 2008

  16. Supernova Types STScI - May 8, 2008

  17. Supernova Spectra • Simultaneousspectrum & photometry = redshift & brightness • Redshift from 615nm SiII line • Equal precision & more accuracy than broadband filters alone STScI - May 8, 2008

  18. Light Curve Calibration STScI - May 8, 2008

  19. Supernova Light Curves • Always get photometry around maximum light • Sample every 5 days STScI - May 8, 2008

  20. Sn Photometric Calibration • Obtain high fidelity external and internal flats in ground tests. • Monitor with internal flats on orbit, plus field stars. • Absolute photometric calibration with DA white Dwarfs. • Sn spectra isolated with differencing. Ad hoc spectral flat extracted from data cube of monochromatic flats. STScI - May 8, 2008

  21. Supernova Survey • Present day & ongoing surveys find hundreds STScI - May 8, 2008

  22. Supernova Survey • Present day & ongoing surveys find hundreds • Destiny will find >3000 SN in 2 yrs. • Most at z~1; requires 3.2 deg2 survey area STScI - May 8, 2008

  23. Weak Lensing STScI - May 8, 2008

  24. Dark Energy and Weak Lensing • Dark Energy equation of state: • w=p/ (w=-1 for ) • modifies: • angular-diameter distance • growth rate of structure • power spectrum on large scales •  wcan be measured from the lensing power spectrum a(t) STScI - May 8, 2008

  25. Predicted Survey Results Assuming a Flat Universe STScI - May 8, 2008

  26. Predicted Survey Results See Knox, Song & Zhan 2006 Not Assuming a Flat Universe STScI - May 8, 2008

  27. Observatory Instrument Radiators Outer Baffle Assembly • Lockheed Spacecraft bus • Goodrich Optical Telescope Assembly • GSFC Science Instrument, Teledyne FPA • GSFC Instrument Outer Baffle Destiny Observatory Spacecraft Bus Fixed Solar Array Goodrich OTA GSFC Science Instrument Telescope Optical Bench 1.65m primary mirror Destiny OTA + Science Instrument Destiny Optics STScI - May 8, 2008

  28. ~1,500,000 km L2 ~340,000km ~1,500,000km Launch Around 2015 STScI - May 8, 2008

  29. Mission Operations / Data Flow STScI - May 8, 2008

  30. Destiny, The Dark Energy Space Telescope STScI - May 8, 2008

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