Joint Efficient Dark-energy Investigation (JEDI)

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Joint Efficient Dark-energy Investigation (JEDI)

• Yun Wang
• May 25, 2006

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• beware of the dark side
• Master Yoda

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JEDI PrototypeUltra Deep Supernova Survey on a
dedicated telescope (1998)

• To determine whether SNe Ia are good cosmological
  
• standard candles, we need to nail the systematic
• uncertainties (luminosity evolution,
  gravitational
• lensing, dust). This will require at least
  hundreds of
• SNe Ia at zgt1. This can be easily accomplished by
  doing
• an ultra deep supernova survey using a dedicated
• telescope, which can be used for other things
• simultaneously (weak lensing, gamma ray burst
• afterglows, etc).
• Wang (astro-ph/9806185)

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Go Deep!(get a lot more SNe at zgt1)

• Wang Lovelave 2001, ApJ Lett 562, 115
• Optimal for measurement of dark energy density

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Apply the idea for an ultra deep SN survey to a
space platform

• Space, the final frontier

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Joint Efficient Dark-energy Investigation (JEDI)

• a candidate implementation of the NASA-DOE
  Joint Dark Energy Mission (JDEM)

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JEDI Collaboration

• PI Yun Wang (U. of Oklahoma)
• Deputy PI Edward Cheng (Conceptual Analytics)
• Lead Scientists
• Interdisciplinary Arlin Crotts (Columbia), Tom
  Roellig (NASA Ames),
• Ned Wright (UCLA)
• SN Peter Garnavich (Notre Dame), Mark Phillips
  (Carnegie Observatory)
• WL Ian DellAntonio (Brown) BAO Leonidas
  Moustakas (JPL/Caltech)
• Eddie Baron (U. of Oklahoma) Steve Bender
  (LANL)
• David Branch (U. of Oklahoma) Stefano Casertano
  (Space Telescope Insti.)
• Bill Forrest (U. of Rochester) Salman Habib
  (LANL)
• Tom Hale (LANL) Mario Hamuy (U. of Chile)
• Katrin Heitmann (LANL) Alexander Kutyrev (NASA
  GSFC)
• John MacKenty (Space Telescope Insti.) Craig
  McMurtry (U. of Rochester)
• Judy Pipher (U. of Rochester) William
  Priedhorsky (LANL)
• Robert Silverberg (NASA GSFC) Volker Springel
  (Max Planck Insti.)
• Gordon Squires (JPL/Caltech) Jason Surace
  (JPL/Caltech)
• Max Tegmark (MIT) Craig Wheeler (UT Austin)

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JEDI Support
NASA JPL Program Management Lockheed Martin
Mission and Spacecraft ITT/Rochester Telescope
and Instrument Rockwell Scientific Focal Plane
Assemblies
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JEDI will answer these questions

• Is dark energy a cosmological constant?
• Does Einsteins general relativity describe our
  Universe?

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Whats special about JEDI

• Super Efficiency Takes gt5000 spectra (including
  all the supernovae in the field of view)
  simultaneously super efficiency for SNe, and
  ideal for spectroscopic galaxy surveys (measuring
  radial baryon acoustic oscillations and
  calibrating photo zs for weak lensing)
• Focus on What Cant be Done From the Ground
  Covers the wavelength range (near to mid IR) not
  easily accessible from the ground, and better for
  the control of systematics
• Multiple Methods for Accurate and Precise
  Constraints on Dark Energy SNe, WL, BAO, etc

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Microshutter Arrays

• AAS 205, 5.07 Microshutter Arrays for JWST
  NIRSpec., S. H. Moseley et al.
• Each shutter consists
• of a shutter blade
• suspended on a
• torsion beam (from
• a support grid) that
• allows for a rotation
• of 90. A motor opens
• the shutters with a
• specially formed
• magnet as a remote
• controlling tool.
• 2D programmable
• slit mask

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JEDI exploiting 0.8-4 µm sweet spot
- lowest sky background region within 0.3-100 µm
wavelengths - rest wavelengths in red/near-IR for
redshifts 0 lt z lt 4
Background sky spectrum Leinert 1998, AAS, 127,
1
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JEDI Necessity of Space Observations

• Supernovae as standard candles
• 1) Observation of z gt 1 SNe Ia (tightens
  constraints on time variation of DE).
• 2) Rest J lightcurves for all SNe Ia (better
  standard candles Krisciunas et al. 2004).
• 3) Multiple spectra per SN Ia (provide
  constraints on systematics).
• Baryon acoustic oscillations as a standard ruler
• 1) Efficiently harvest millions of galaxy
  redshifts in the contiguous range 0.5ltzlt2.
• 2) H(z) measured as a continuous free function.
• Weak lensing cosmography
• 1) Stable and smaller point spread function.
• 2) Higher galaxy density and higher mean galaxy
  redshift from deep NIR imaging.
• 3) Spectroscopic reshift information for
  tomography.
• Continuous H(z) to better than 2 in ?z0.2 bins
  for 0 ? z ? 2.

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JEDI the Power of Three Independent Methods

• Supernovae as standard candles
• luminosity distances dL(zi)
• Baryon acoustic oscillations as a
• standard ruler
• cosmic expansion rate H(zi)
• angular diameter distance dA(zi)
• cosmic LSS growth rate G(z)
• Weak lensing cosmography
• ratios of dA(zi)/dA(zj)
• cosmic LSS growth rate G(z)
• The three independent methods will provide a
  powerful cross check,
• and allow JEDI to place precise constraints on
  dark energy.

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Measurement of the Cosmic Expansion History
Current
JEDI
Wang Tegmark (2005) Wang Mukherjee (2006)
Wang (2006)
The JEDI mission will measure H(z) for 0 lt z lt 2
using both SNe and Baryon Acoustic Oscillations
(BAO), thus enabling model-independent
constraints on the time dependence of dark energy
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JEDI Data

• Supernovae 4000-14,000 type Ia supernovae with
  well-sampled light curves and good quality
  spectra.
• Baryon Acoustic oscillations data 10-100
  million galaxy spectra (H? emission line
  galaxies) over 1000-10,000 square degrees, with
  0.5 z 2.
• Weak lensing data accurate measurements of
  galaxy shapes over 1000-10,000 square degrees
  to H ? 23 (median redshift 1 to 1.5).
• Shear selected galaxy clusters over 10,000 sq
  degrees
• Other (what data would you like to have?)

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• JEDI science requirements map
• directly into instrument design
• parameters
• JEDI builds upon heritage
• from Spitzer and technology
• from JWST.

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Key Scientific Requirements Flowdown
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• JEDIs preliminary optical design provides a
  proof-of-concept point design combiningimaging
  and spectroscopic performance in a compact,
  packagable design. Further simplifications may be
  the results of design studies performed during
  the concept study.

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• The JEDI spacecraft easily fits within the
  payload envelope of the Delta IV 4 meter
  configuration shown.

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• JEDI will use the JWST/NIRSpec microshutter
  array without modification.

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• The HAWAII-2RG multiplexer, used in both
  focal planes, has extensive ground based
  heritage.

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• The unique sky coverage of the JEDI focal
  planes allows identification of spectrographic
  targets by the imager due to the offset of the
  imaging and spectral focal planes.

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JEDI Deep Campaign

• The spacecraft repeats a pattern that allows
  spectral targets to be identified by imaging and
  selected by the microshutters on the following
  scan line.

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JEDI Wide Campaign

• JEDI scans successive quadrants while
  obeying sun and pointing constraints. Imaging
  provides spectroscopy targets as in the Deep
  Campaign.

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Functional Concept

• a) the flight segment mounted in the fairing of a
  Delta-IV 4-m configuration.
• b) FOVs of the imaging and spectroscopic
  channels projected onto the sky.
• c) a preliminary optical point design
  demonstrates that the desired functions are
  packageable.
• d) an exploded view of the JWST/NIRSpec
  microshutter array. This exact hardware is
  baselined for JEDI. Practical packaging
  constraints for this hardware cause the small
  horizontal gap between the two spectroscopic
  fields-of-view in panel (b).
• e) a mechanical mockup of a 5x7 focal plane array
  built by RSC to demonstrate fabrication and
  alignment processes.
• f) a single hybrid detector basedon HAWAII-2RG
  design, being produced for 3 JWST instruments.

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Competing Mission Concepts for JDEMSNAP,
JEDI, DESTINYADEPT, DUNE (?), X, Y

• Competition helps ensure that the best science
  gets done

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JDEM Timeline

• July 2006 proposals selected for NASA JDEM
  concept study (up to 2M a year for two years)
• 2008 NASA/DOE Announcement of Opportunity (AO)
  for JDEM
• 2017 JDEM launch

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Conclusion

• A successful JDEM can place robust and precise
  constraints on the time dependence of ?X(z) and
  G(z). This will have a fundamental impact on
  particle physics and cosmology.
• JEDI is a powerful mission concept for JDEM.
• JEDI has unprecedented capability for ancillary
  science.

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The End