R. Pain9/18/2008 LSST-SNAP complementarity Reynald Pain IN2P3/LPNHE Paris, France Page 1.
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Transcript of R. Pain9/18/2008 LSST-SNAP complementarity Reynald Pain IN2P3/LPNHE Paris, France Page 1.
R. Pain 9/18/2008
LSST-SNAP complementarity
Reynald Pain
IN2P3/LPNHE Paris, France
Page 1
R. Pain 9/18/2008
True:
1. Target Dark Energy (and Dark Matter) as primary science2. Use wide field imager as (main) instrument 3. Hope to start operating in ~20154. Are competing for (some of) the same money
But …
LSST vs SNAP (and vice-versa)
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R. Pain 9/18/2008
LSST & SNAP apparatus
• Primary mirror : ~2m• Field-of-view : ~ 1 deg2
• 6 filters in the visible : 320 nm -> 1100 nm• 3 filters in NIR (->1700 nm)• low-z spectrograph
• Primary mirror : 8.4 m• Field-of-view : ~ 10 deg2
• 6 filters in the visible : 320 nm -> 1100 nm
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R. Pain 9/18/2008
LSST & SNAP surveys
SNAP Survey Area(sq.deg) Depth(AB mag) ngal(arcmin-2) Ngal
Deep/SNe 15 30.3 250 107
Wide 4000 27.8 100 108.5
Panoramic 7000-10000 26.7 40-50 109
LSST Survey
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SNAP & LSST strategies for Supernovae
SNAP: Area : 2x7.5 sq. deg.
Cadence : 4 days
Imaging and spectroscopy
Total nb of SN : ~ 2000
Need for “nearby” SN (ground)
Light curve modeling requires lots of SN
LSST: full sky, twice a week
=> 250000 SN/yr !
well measured subsample at z<1
Some DE models require SN at z>1
Dust modeling requires IR meas.
R. Pain 9/18/2008 6
SNAP & LSST strategies for Weak Lensing
9-band photometry (incl NIR) helps for phot-z
LSST: 200 exposures per sky patch will yield negligible PSF induced shear systematics
SNAP: increase the number of resolved galaxies (spatial resolution) and PSF stability
Cosmic shear signal
Stars
SNAP and LSST will have very different systematic uncertainties
R. Pain 9/18/2008
Rely on the same techniques (SN, WL, BAO, ..) to constraint DE but use a very different instrumental approach
DE is a difficult measurement. Improving on current (+ near future) constraints will be extremely
difficult and will in fine come to how well one does on controlling the systematic uncertainties
LSST and SNAP are complementarity in particular when dealing with systemactic uncertainties
Combined, they will yield improved constraints on Dark Energy
LSST and SNAP
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Cosmological parameters (1st year)Cosmological parameters (1st year)
68.3, 95.5 and 99.7% CL68.3, 95.5 and 99.7% CLGreen SNLS, Blue SDSS/BAO 2005Green SNLS, Blue SDSS/BAO 2005
MM = 0.271 +/- 0.021 (stat) +/- = 0.271 +/- 0.021 (stat) +/- 0.007 (syst)0.007 (syst)
w = -1.023 +/- 0.090 (stat) +/- w = -1.023 +/- 0.090 (stat) +/- 0.054 (syst)0.054 (syst)