Cosmic Structures: Challenges for Astro-Statistics * Data compression – e.g. P(k) * Features in P(k) * Parameter estimation and model selection * Beyond the 2-point.
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Cosmic Structures: Challenges for Astro-Statistics * Data compression – e.g. P(k) * Features in P(k) * Parameter estimation and model selection * Beyond the 2-point statistic * The big questions: dark matter, dark energy, galaxy formation Ofer Lahav Department of Physics and Astronomy University College London F 2MASS Galactic chart (Tom Jarrett) Redshift Surveys The Cosmic Web SDSS CfA Great Wall Great Attractor 2dFGRS Is the universe a fractal? A short answer: NO N(<R) / RD D=1.2 clumpiness Small scales Correlation Function per Type dP / n [1+(r)] dV (r) = (r/r0)- Why a power law? different slopes for blue and red explained by different halo Occupation numbers Madgwick et al. 03 Halo model for LSS Picture credit: Cooray & Sheth (2002) The halo model – the ‘new biasing’ P(k) = Plin+Phalo Truncated NFW fit with C=2.4§ 0.2 using 2dF Groups Collister & Lahav, astro-ph/0412516 Neutrinos decoupled when they were still relativistic, hence they wiped out structure on small scales 112 neutrinos per cm3 CDM+HDM WDM CDM From 2dF < 0.04 ; M < 1.8 eV (Elgaroy & OL 2003) From Ly-a+SDSS +CMB M < 0.17 eV (Seljak et al. 2006) Mock Universes: Models vs. Epoch Same amplitudes, different phases Chiang & Coles 2000 Non-Gaussianity in LSS Guassian density contrast pdf will turn into (roughly) a log-normal pdf. Gravity is an amplifier: the rich gets richer the poor gets poorer • Needed: non-G tests, shape finders CiC 2dF early type Wild et al 2004 Minkowski functionals ( ) 2 Wavelet MF V3 applied to 2dF Martinez et al. Are the 2dFGRS superclusters anomalous? 7 Abell clusters 77 groups (>8) 20 Abell clusters 93 groups (>8) Baugh et al., Erdogdu et al., Murphy & OL MegaZ-LRG *Training on ~13,000 2SLAQ *Generating with ANNz Photo-z for ~1,000,000 LR over 5,000 sq deg z = 0.046 Collister, Lahav, Blake et al. power spectra out to 1 Gpc vary 4 parameters Non-linear P(k) Linear P(k) Blake et al., astro-ph/0605303 Minimum fitted multipole Baryon Wiggles as Standard Ruler The Dark Energy Survey • 4 complementary techniques: * Cluster counts & clustering * Weak lensing * Galaxy angular clustering * SNe Ia distances Build new 3 deg2 camera on the CTIO Blanco 4m Construction 2005-2009 Survey 2009-2014 (~525 nights) 5000 deg2 g, r, i, z 300, 000, 000 galaxies with photo-z Science goal: w to ~5-10% on each technique LSS - The Steps Ahead * Spetcroscopic and photometric Surveys Of 106 – 108 galaxies * Beyond the 2-point statistic: higher meoments, MF, shape finders, phases… * The interplay with galaxy formation * Dark energy surveys (BAO, WL) * The VO infra-structure