1 / 24

Cosmic Structures: Challenges for Astro-Statistics

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

burton-saunders
Télécharger la présentation

Cosmic Structures: Challenges for Astro-Statistics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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

  2. F 2MASS Galactic chart (Tom Jarrett)

  3. Redshift Surveys

  4. The Cosmic Web SDSS CfA Great Wall Great Attractor 2dFGRS

  5. Is the universe a fractal?A short answer: NO N(<R) / RD D=1.2

  6. clumpiness Small scales

  7. 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

  8. Halo model for LSS Picturecredit: Cooray & Sheth (2002)

  9. 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

  10. 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)

  11. Mock Universes: Models vs. Epoch

  12. Same amplitudes, different phases Chiang & Coles 2000

  13. 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

  14. CiC 2dF early type Wild et al 2004

  15. Minkowski functionals

  16. ( ) 2

  17. Wavelet MF V3 applied to 2dF Martinez et al.

  18. Are the 2dFGRS superclustersanomalous? 7 Abell clusters 77 groups (>8) 20 Abell clusters 93 groups (>8) Baugh et al., Erdogdu et al., Murphy & OL

  19. 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.

  20. power spectra out to 1 Gpc vary 4 parameters Non-linear P(k) Minimum fitted multipole Linear P(k) Blake et al., astro-ph/0605303

  21. Baryon Wiggles as Standard Ruler

  22. 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 deg2g, r, i, z 300, 000, 000 galaxies with photo-z Science goal: w to ~5-10% on each technique

  23. 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

More Related