Cosmology with Future Optical/NIRSurveys
Hu ZhanNational Astronomical Observatories of China
Chinese Academy of Sciences

Gain of CCD survey:
QE (depth), dynamicalrange (photometryprecision), digitization(computer processing).

2006

Objectives:• Cosmic Dawn
• New Worlds• Physics of theUniverse

ESA
EuclidPriority: Large Surveys

 Type Ia supernovae: luminosity distance Weak gravitational lensing: angular diameter distance,
growth of structure, matter power spectrum
 Baryon acoustic oscillations: angular diameter distance,
Hubble parameter, structure growth rate
 Cluster counting: volume/distance, growth of structure Strong lensing: Hubble constant, time-delay distance CMB: angular diameter distance, integrated Sachs-Wolfe
effectExpansion (DA, DL, H), growth, & power spectrum
Dark energy, dark matter, gravity, neutrino mass,cosmological parameters…

Large surveys!

Eisenstein, Seo, & White (2007)

BaryonAcoustic
Oscillations

dg(x+Dx)
SDSS LRGs
Eisenstein
et al (2005)

dg(x)Deep Lens Survey, Tyson & Wittmand g x   ng x  / ng  1 Dx    Dx   d g x d g x  Dx P k   FT  Dx Power Spectrum

Correlation
Function

BaryonAcoustic
Oscillations
in multipole
space

Angular PS
Zhan (2006)

Hong et al. (2012)

CMB temp. fluctuations (WMAP)
Imprints on the matter power
spectrum (White 2005)

BAOs inmultipole
space

RS~150 Mpc

Angular diameter
distance(Sound horizon atrecombination)

RS = Dq DA= cDz /HLSSTDLSgalaxysurveyangular PS

Redshift distortion
Growth rate
Test gravity (Zhang et al. 2008)

Auto PowerSpectrum

Kernel ∝ galaxy distribution in true-redshift spaceCross PowerSpectrum

Kernel ∝ galaxy distribution in true-redshift space

Overlap of galaxy distributions
 Cross power spectrum(Limber approx)

Cross PowerSpectrum

Kernel ∝ galaxy distribution in true-redshift space

Overlap of galaxy distributions
 Cross power spectrum(Limber approx)

Cross PowerSpectrum

Kernel ∝ galaxy distribution in true-redshift space

Overlap of galaxy distributions
 Cross power spectrum(Limber approx)

Cross PowerSpectrum

Kernel ∝ galaxy distribution in true-redshift space

Overlap of galaxy distributions
 Cross power spectrum(Limber approx)

Kernel ∝ galaxy distribution in true-redshift spaceggPij   l gg2
dz
HDWWDAijd 3 c DA n z gW i  bz  ini

2

2

sheared imagea = 4GM/bc2

DLSshearDLS
g ~ q  D 4GM/bc2
SCosmology changes
geometric distance factors

DSbq

Gravity & Cosmology change
the growth of mass structure

The shear correlation originates from correlation of the foreground mass.
Note: the cosmic shear, i.e., weak lensing signal, is much weaker!

g(q+Dq)

Hoekstraet al (2005)g(q)1.1o1.1o simulated shear field by Hamana E  D q    E  D θ   g E  θ g E  θ  D θ  B D q   0P     FT  E  D q Power Spectrum

Correlation
FunctionSong & Knox(2004)

D T ISW   d No change
in potential

No linear
ISWdd a  x 

There is no linear ISW effect inan EdS universe, because D(a)=a.
Need to break D=a• with extra component(s) e.g.,dark energy, or• go nonlinear (Rees—Sciamaeffect).
The RS effect is expected to be much smaller
than the linear ISW effect in LCDM.

dddD a daCross correlations

Supercluster
Granett, Neyrinck, & Szapudi (2008, 2009)

Type Ia Supernova
Luminosity evolution, Galactic & host-galaxy dust extinction, contamination.
Weak lensing
Shear calibration: Properties of additive & multiplicative shear errors?
Photo-zs: What is the error distribution function? How and how well can wecalibrate it? What is the impact of non-Gaussian photo-z errors on cosmologicalconstraints? How about catastrophic redshift errors?
Nonlinear evolution: Percent-level calibration of the nonlinear power spectrum at k
< 1 h/Mpc? Baryonic influence on the dark matter distribution?
Intrinsic alignment: Local & large-scale, intrinsic—intrinsic, gravitational—intrinsicalignments. How to remove/model the effects?
Baryon Acoustic Oscillations
Nonlinear evolution: Shift of the BAO scale? Higher-order statistics? Parameter
estimation from non-Gaussian data?
Galaxy bias: Scale dependence? luminosity dependence?
Photo-zs: See WL
Redshift distortion: Accurate calibration with N-body simulations?
Cluster Counting
Mass—observable relation: mean & variance?

Abdalla et al. (2008)

Zhan et al. arXiv:0902.2599
A joint analysis of the shear and galaxy overdensities for the same set of galaxies
involves galaxy—galaxy, galaxy—shear, and shear—shear correlations, which enable
some calibration of systematics that would otherwise adversely impact each probe.
While the WL constraints on the dark energy equation of state (EOS, w = p/r)
parameters, w0 and wa, as dened by w = w0+wa(1-a), are sensitive to systematic
uncertainties in the photo-z error distribution, the joint BAO and WL results remain
fairly immune to these systematics.

• Data Reduction• Data Management• Simulation• Data Analysis

CL0024
Colley, Tyson,& Turner(1996)

Background
Detection
Deblending
PSF
Photometry
Astrometry
Stacking
Shape
Time series
Classification
Mask
Selection Func…
OK by hand forone obj, butbillions?

End-to-end simulations are needed to develop, test andverify large projects, e.g.,• Hardware/software specs, design, implementation,performance• Survey strategy & optimization• Fidelity of analysis pipelines
Challenges:• Complex system• Incomplete physics (simulate the universe with pieces
missing or over-simplified)• Observational effects• Shear volume of simulations needed for analyses• Complex instrumental and observational effects(much stringent requirement in the big data era)
• Statistics of billions of objects over a hugevolume (e.g., n-point correlations)• Precise characterization of the likelihood of data
give a model (large suite of realistic simulations)• Exploring high dimensional parameter space(could be hundreds)