Cosmic Structures: Challenges for Astro-Statistics

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Cosmic StructuresChallenges 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

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F
2MASS Galactic chart (Tom Jarrett)
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Redshift Surveys
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The Cosmic Web
SDSS
CfA Great Wall
Great Attractor
2dFGRS
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Is the universe a fractal?A short answer NO

N(ltR) / RD
D1.2
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clumpiness
Small scales
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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
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Halo model for LSS
Picture credit Cooray Sheth (2002)
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The halo model the new biasing
P(k) PlinPhalo
Truncated NFW fit with C2.4 0.2 using 2dF
Groups
Collister Lahav, astro-ph/0412516
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Neutrinos decoupled when they were still
relativistic, hence they wiped out structure on
small scales 112 neutrinos per cm3
WDM
CDMHDM
CDM

From 2dF ?? lt 0.04 M? lt 1.8 eV
(Elgaroy OL 2003) From Ly-aSDSS CMB M? lt
0.17 eV (Seljak et al. 2006)
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Mock Universes Models vs. Epoch
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Same amplitudes, different phases
Chiang Coles 2000
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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

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CiC 2dF early type
Wild et al 2004
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Minkowski functionals
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(
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Wavelet MF V3 applied to 2dF
Martinez et al.
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Are the 2dFGRS superclustersanomalous?
7 Abell clusters 77 groups (gt8)
20 Abell clusters 93 groups (gt8)
Baugh et al., Erdogdu et al., Murphy OL
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MegaZ-LRG Training on 13,000
2SLAQGenerating with ANNz Photo-z for
1,000,000 LR over 5,000 sq deg
?z 0.046
Collister, Lahav, Blake et al.
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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
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Baryon Wiggles as Standard Ruler
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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
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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