Presentaci

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Cross-correlation of WMAP 3rd year and SDSS DR4
new evidence for dark energy
Anna Cabre, Enrique Gaztañaga, Pablo Fosalba,
Marc Manera, Francisco Castander astro-ph/0603690
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Motivation Obtain dark energy from the ISW
effect crosscorrelating CMB and LSS
Summary Integrated Sachs Wolfe effect
background Large scale structure data and CMB
data Analysis, errors... Results Conclusions and
Future
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Integrated Sachs Wolfe effect ISW is the
gravitational redshift that photons coming from
CMB undergo when they fall in a deep potential
and come out from a smoother one. This change in
potential can be created by curvature or by dark
energy. Assuming that the universe is flat (from
WMAP results), ISW indicates the existence of
dark energy.
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How to detect ISW? Temperature fluctuations
created by ISW are difficult to see in power
spectrum, and the results seem to supress that
Alternative Cross correlating CMB temperature
with potential traced by LSS (Crittenden Turok
1996)
Wayne Hu
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CMB data
LSS data
SDSS DR4
WMAP 3rd year
-5200 sq deg (13 sky) -Selection of subsamples
with different redshift distribution -3 magnitude
subsamples with r18-19, r19-20 and r20-21 with
106 107 galaxies -high redshift Luminous Red
Galaxy (Eisentein et al. 2001) -Mask avoids
holes, trails, bleeding, bright stars and
seeinggt1.8
V-band (61 Hz) HEALPix tessellation Kp0 mask
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ISW in equations...
Limber approximation
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wGG(q) a b2s82 f(Wm) wTG(q) a b s82 g(Wm) b
s8from GG x s8 from WMAP TG factor b s82 fix
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Autocorrelation results (galaxy-galaxy)
Slices with more S/N b s8 20-21
0.90-0.96 LRG 1.02-1.12
bias
deep magnitude
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GG fitting for slice 20-21
GG fitting for slice high redshift
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Redshift selection function
Jack-knife errors
LRG
20-21
Singular Value Decomposition (SVD)
c2 distribution
r20-21 zc0 z00.2 zm0.3 LRG zc0.37
z00.45 zm0.5
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r20-21 S/N3.6
LRG S/N3.
S/N total4.7
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signal to noise picture...
Covariance for MC
Covariance for JK
Covarianca matriu per DR4 2021 o 8888
Covarianca matriu simulacions MC
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For a flat universe, with bias, sigma8 and w-1
fix.... dark energy must be...
68 0.80-0.85
95 0.77-0.86
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Can we obtain information about w?
Contour 1, 2 sigma 1 dof
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Errors JK, reliable??
CORRELACIÓ GG
CORRELACIÓ TG
76 JK
38 JK
76 JK
38 JK
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1000 simulations of galaxies and temperature
fluctuations with ISW
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(No Transcript)
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Conclusions There is no change of the ISW
detection from WMAP1 to WMAP3 To improve we
need to sample a larger area (SDSS DR5) or larger
volume (DES) and more slices...
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Dark Energy Survey predictions...
GG prefers higher omega matter than
TG, signal TG too high.. why? We can not break
the degeneracy between WL and w with ISW and
fsky0.13