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Cross-Correlation of 2MASS with WMAP3: Implications for ISW Anaïs Rassat (University College London) Kate Land (Imperial College London) Ofer Lahav (University College London)
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Integrated Sachs-Wolfe Effect
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2MASS Galaxy Survey Publicly available eXtended Source Catalogue (XSC) J, H, K bands (Near Infrared) ~1,650,000 Galaxies with magnitudes corrected for Galactic extinction. Analysis includes 69% sky & 1,250,000 Galaxies Compare with Cabré et al. 2006 (SDSS DR4): ~16% (z ~ 1) Scranton et al. 2003 (SDSS – LRGs) : ~ 8% (z ~ 0.45) Fosalba and Gaztañaga 2003 (APM): ~10% (z ~ 0.15)
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2MASS ⊗ WMAP3 Auto-Correlation Cross-Correlation AoE statistic
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Auto-Correlation Function: ACF EXACT IN LINEAR THEORY
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Constant linear bias b from C gg (ℓ) 12 < K 20 < 14
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Best fit
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2MASS ⊗ WMAP3 Auto-Correlation√ Cross-Correlation AoE statistic
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3 rd Year WMAP Foreground reduced maps of Q,V and W bands Q band (41 GHz) V band (61 GHz) W band (94 GHz) Images from WMAP Science Team
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Method: Follow Afshordi et al. 2004 (WMAP1 ⊗ 2MASS) Perform Cross-Correlation in Harmonic Space: Cut Kp2 mask on WMAP3, Cut out 31% of 2MASS sky
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ALL of 2MASS with ILC map CORRELATION?
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Colourful Correlation
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2MASS 4 Magnitude Bins with ILC map POSITIVE CORRELATION TREND FOR LOW MULTIPOLES?
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Four Magnitude Shells ⊗ Q, V, W, ILC WMAP3 maps Achromatic Trend 1σ from 500 simulations of CMB with 2MASS WMAP3 / 2MASS
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Changes between WMAP1 & WMAP3 ■ WMAP3 □ WMAP1 Why is there a difference?
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Theory Exact in linear theory: Small angle approximation:
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Predicted Cross-Correlation: Exact & Small Angle Approximation: ℓ ~ 11
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Shells with z ~ 0.067 (>2.10 5 gal) z ~ 0.084 (>4.10 5 gal) ∆χ 2 = χ 2 ISW - χ 2 NULL = 2 ☼
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OPEN COSMOLOGIES
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Or f ~ 1.7 (~1.6)
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Model Dependent Statistic Assume there is Dark Energy in a Ω k =0 Universe C gT [DATA] = h* C gT [ISW_fiducial] Without prior on σ8:h ~ 1.7 or 2σ detection (Null detection corresponds to h < 0) With prior on σ8:h ~ 1.6 Etc.. Full Parameter Space needs to be investigated
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ALTERNATIVE FIDUCIAL MODELS h ~ 1.7 2σ Detection
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2MASS ⊗ WMAP3 Auto-Correlation √ Cross-Correlation√ AoE statistic
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Axis of Evil ☼ ℓ=2 ℓ=3ℓ=4ℓ=5 WMAP3 2MASS
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Summary: 2MASS ⊗ WMAP3 WMAP3 ⊗ 2MASS : within 1σ [NULL] (Model Independent) ISW (fiducial) : within 1σ [NULL] C gT DATA ~ 1.7 C gT FIDUCIAL (Model Dependent 2σ Detection) AoE(WMAP) ≠ AoE(2MASS) Thanks to Filipe Abdalla, Niayesh Afshordi, Sarah Bridle, Carlo Contaldi, for comments, advice and assistance.
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CCL Find 2MASS b = 1.4 Cross-correlate 2MASS with WMAP3: –Slight change from 2MASS with WMAP1 –Visible positive achromatic cross-correlation, suggestive of ISW effect, but also consistent with Null Hypothesis. –Data fits ISW effect “too well” –Marginalization over parameter space makes cross- correlation even less significant. Axis of Evil: other statistical test –No significant correlation between AOE of WMAP and
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