DUNE PPARC

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DUNE The Dark UNiverse Explorer
John Peacock (Edinburgh) For the UK DUNE
Collaboration Edinburgh A. Heavens, A.
Taylor, J. Dunlop, A. Lawrence Oxford J. Silk,
G. Dalton, L. Miller, A. Slyz Durham C. Frenk,
M. Ward, S. Cole, R. Bower, A. Edge, T.
Shanks UCL O. Lahav, S. Bridle and the
European DUNE Collaboration Saclay A.
Réfrégier IAP Y. Mellier Marseille B.
Milliard CNES J. Michaud Bonn P. Schneider
Munich R. Bender Heidelberg H.-W. Rix
Zurich S. Lilly Lausanne G. Meylan Rome
R. Scaramella
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Cosmology Concordance Model

Heavy elements 0.03 Neutrinos 0.3 Stars
0.5 H He gas 4 Dark matter 20 Dark Energy
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• Outstanding questions
• initial conditions (inflation?)
• nature of the dark matter
• nature of the dark energy
• ? Science goals for DUNE

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Probing Dark Energy
Is the Dark Energy - Vacuum zero-point energy?
(cosmological constant) - Dynamical? (scalar
field with potential) - An illusion? (artifact of
higher dimensions) The big question does the DE
density change with time? How - Geometry
evolving DE changes distance-redshift relation -
Dynamics and alters the growth of density
perturbations
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Probe 1 Gravitational lensing
Image distortion depends on - D(z) via baseline -
growth of structure
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Shear Data Ground vs Space
Typical cosmic shear is 1, and must be
measured with high accuracy
Space small and stable PSF ? larger number of
resolved galaxies ? reduced systematics

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ground data Photometric redshifts

• Will need redshifts for 109 galaxies - possible
  to 5 with ground-based Dark Energy Survey etc.
• But need 1-2 micron for z gt1 - impossible to get
  deep enough from ground (sky brightness)

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Probe 2 Supernovae
Ground vs HST
Standard candles distances to 5 Currently
samples of few hundred Space resolution essential
for high z
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DUNE Dark UNiverse Explorer

• Mission baseline
• 1.2m telescope
• FOV 0.5 deg2
• PSF FWHM 0.23
• Pixels 0.11
• GEO (or HEO) orbit
• Surveys (3-year initial programme)
• WL survey 20,000 deg2 in 1 red broad band, 35
  galaxies/amin2 with median z 1, ground based
  complement for photo-zs
• Near-IR survey (J,H). Deeper than possible from
  ground. Secures z gt 1 photo-zs
• SNe survey 2 60 deg2, observed for 9 months
  each every 4 days in 6 bands, 10000 SNe out to z
  1.5, ground based spectroscopy

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DUNE depth - optical
Abell 2218
Dune 1500s integration in RIZ (566nm
1micron) Same depth (IAB 25 at 10s) as
HST/WFPC2 in 3 orbits (better throughput)
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DUNE vs SDSS
Abell 1689 SDSS vs 3 mags deeper (plus better
PSF)
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DUNE depth - IR
2MASS All sky at 1-2 micron to AB 16 DUNE 7
mags deeper
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Expected precision on Dark Energy
Focus on equation of state w P / r c2 and its
evolution. w1 tells you fractional change in
DE density since redshift 1 - currently
constrained to be lt 10

• DUNE Lensing
• Can detect 0.2 change in DE density
• cf. DES target 4
• DUNE Supernovae
• Can detect 0.5 change in DE density
• cf. DES target 4

.
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Science Goals with DUNE

• Primary goal Cosmology with WL and SNe
• Measurement of the evolution of the dark energy
  equation of state (w,wa) from z0 to 1
• Statistics of the dark matter distribution (power
  spectrum, high order correlation functions)
• Reconstruction of the primordial power spectrum
  (constraints on inflation)
• Cross-correlation with CMB
• Search for correlations of Galaxy shear with ISW
  effect, SZ effect, CMB lensing
• Search for DE spatial fluctuations on large
  scales
• Study of Dark Matter Haloes
• Mass-selected halo catalogues (about 80,000
  haloes) with multi-l follow-up (X-ray, SZ,
  optical) halo mass calibration
• Strong lensing probe the inner profiles of
  haloes
• Galaxy formation
• Galaxy bias with galaxy-galaxy and shear-galaxy
  correlation functions
• Galaxy clustering with high resolution morphology
  
• Core Collapse supernovae
• constraints on the history of star formation up
  to z1
• Fundamental tests
• Test of gravitational instability paradigm
• Dark Energy clustering
• Distinguish dark energy from modification of
  gravity

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Current Status

• CNES
• Pre-study (Phase 0) performed in 2005 by CNES,
  with subcontracting to EADS Astrium
• Conclusion optical-only experiment can be ready
  by 2015 within cost cap. IR component may need
  additonal partner contributions
• ESA
• Proposed as a theme for ESAs Cosmic Vision in
  2004
• ESO/ESA working group on cosmology to coordinate
  ground/space surveys
• Consortium France , UK, Germany, Switzerland,
  Italy

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International Context
NASA/DoE/NSF Dark Energy Task Force A Joint
Dark Energy Mission satellite is a strong
eventual priority, comparable to the square
kilometre array (2020 ?)
ESA-ESO Cosmology Working Group DUNE with
ground-based colour data is a perfect interagency
synergy. With a simpler satellite, can attain
most JDEM science sooner

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Conclusions

• DUNE novel concept fast mission moderate cost
  centred on Weak Lensing and Supernova surveys,
  Ground/Space Synergy, build on strong UK theory
  experience
• Unique constraints on Dark Energy and Dark Matter
  from two independent cosmological probes
• Huge range of extra science from super-SDSS
  super-2MASS
• Fruitful CNES Phase 0 mission with controlled
  systematics feasible limited risks
• Mission enhancement possible with additional
  national contributions larger telescope, more
  bands for WL survey, broader wavelength range
  (NIR coverage)