Beyond CDM: Status and Prospects from Redshift Surveys Beth Reid - - PowerPoint PPT Presentation

Beth Reid Cosmology Data Science Fellow UC Berkeley Center for Cosmological Physics/ Lawrence Berkeley National Lab

in collaboration with the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS)

Beyond ΛCDM: Status and Prospects from Redshift Surveys

image courtesy Chris Blake and Sam Moorfield

Thursday, January 15, 2015

The observable universe to scale*

z=0.7

z=1091

Oslo: Beyond ΛCDM

BAO standard ruler = 151.4 ± 0.66 Mpc [Planck XVI] SDSS Ly-α z ≈ 2.4 SDSS galaxies z < 0.7

SDSS image courtesy Anze Slosar

Beth Reid

growth of fluctuations ~1000x

Thursday, January 15, 2015

Questions to address

• How do we and how should we extract cosmological

information from these CMB and LSS maps?

• What have we learned?
• Where/how should we look next?

Beth Reid Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Three regimes of LSS

Beth Reid

Linear Mildly nonlinear Highly nonlinear/ galaxy formation

> 30 h-1 Mpc 2 - 30 h-1 Mpc < 1 h-1 Mpc

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Three regimes of LSS

Beth Reid

Highly nonlinear/ galaxy formation

< 1 h-1 Mpc

• “Too big to fail”, etc.
• Galaxy cluster cosmology
• Covered in other talks

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Three regimes of LSS

Beth Reid

Linear

> 30 h-1 Mpc

• Physics is linear
• Fluctuations are Gaussian
• (Almost) all information

contained in 2-point correlations

• ΛCDM passes stringent

tests with a few intriguing 2-2.5σ discrepancies

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

CMB-LSS consistency: spectrum of matter fluctuations

• Planck tightly constrains the spectrum of fluctuations

in the “linear” regime of LSS, k = 0.01 - 0.2 h Mpc-1.

Beth Reid

PRELIMINARY! [source: Efstathiou @ Ferrara]

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

CMB-LSS consistency: spectrum of matter fluctuations

• Best fit Planck model compared to halo P(k) from

SDSS-II LRGs [Reid et al 2010]

Beth Reid

Planck best fit χ2 = 40.4/40 dof vs 40.0 (LRG only)

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

CMB-LSS consistency: spectrum of matter fluctuations

• Similarly good

agreement with SDSS-III BOSS DR11 [Beutler et al. 2014]

Beth Reid Oslo: Beyond ΛCDM

Thursday, January 15, 2015

CMB-LSS consistency: spectrum of matter fluctuations

• CMB-LSS

consistency supports CDM as the backbone of structure formation, with no (little) DE clustering

• n these scales

Beth Reid

Dodelson, arXiv:1112.1320

CDM TeVeS

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

• The CMB calibrates the baryon acoustic oscillation

(BAO) standard ruler [sBAO = 147.5 ± 0.6 Mpc, Planck XVI]

Beth Reid

CMB-LSS consistency: expansion history

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

BAO in SDSS-III BOSS CMASS sample: 1% distance constraint at z=0.57

Beth Reid

P(k)/Psmooth(k) s2 ξ(s)

BOSS collab., MNRAS 441, 24 (2014)

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

PRELIMINARY! [source: Efstathiou @ Ferrara]

• 1% Planck ΛCDM

prediction and 1% galaxy BAO measurement agree!

CMB-LSS consistency: expansion history

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

• ≈ 2.5σ tension with flat

ΛCDM

• Offset in DA-DH plane

difficult to produce in a physical model

• See arXiv:1411.1074 for

joint examination of all BAO measurements and many cosmological models

CMB-LSS tension: Ly-α BAO

Delubac et al., arXiv:1404.1801

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Clustering anisotropy provides a measurement

• f the peculiar velocity amplitude (fσ8).

Beth Reid

r⊥ (h-1 Mpc) r∥ (h-1 Mpc)

BOSS DR11, Samushia, BR, et al. 2013

ξ(r⊥, r∥) s (h-1 Mpc)

angle-average anisotropy

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

• *Assuming* Planck ΛCDM

expansion history, RSD measurements prefer lower fσ8 than Planck at ≈ 1.9σ.

CMB-LSS consistency: Growth rate of stucture with RSD

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

• RSD measurements

rule out nonlocal gravity at 7.8σ.

RSD constrains modified gravity

Oslo: Beyond ΛCDM

Dodelson and Park, PRD 90, 043535 (2014)

Thursday, January 15, 2015

Three regimes of LSS

Beth Reid

Mildly nonlinear

2 - 30 h-1 Mpc

• Under-valued -- lots of S/N available!
• non-Gaussian -- what should we measure?
• Beyond reach of perturbative models

(simulations required)

• Requires somewhat detailed statistical

description of galaxy <-> matter connection

• Particularly interesting for modified

gravity models(?)

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

r⊥ (h-1 Mpc) r∥ (h-1 Mpc)

BOSS DR11, Samushia, Reid et al. 2013

ξ(r⊥, r∥)

Reid et al. 2014

Example 1: Constraining the growth rate in the nonlinear regime

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

Reid et al. 2014

Example 1: Constraining the growth rate in the nonlinear regime

Oslo: Beyond ΛCDM

• Anisotropic clustering reflects

two competing effects:

• A. Pairwise infall from gravitational

attraction

• B. small-scale (≈ incoherent)

velocity dispersion

• Must marginalize over galaxy <->

matter mapping to extract A.

• Simulations required for

theoretical prediction.

Thursday, January 15, 2015

Beth Reid Oslo: Beyond ΛCDM

Constraining the growth rate in the nonlinear regime: model tests

Thursday, January 15, 2015

Beth Reid

• DR11 large scales: fσ8 = 0.447 ± 0.028
• DR10 small scales: fσ8 = 0.450 ± 0.011
• Planck ΛCDM prediction: fσ8 = 0.480 ± 0.010

Constraining the growth rate in the nonlinear regime: 2.5x tighter constraint!

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Modified gravity implications: effects on P(v12,r)

Beth Reid

~1-2 h-1 Mpc enhancement in v(r) at r =5 h-1 Mpc for both f(R) and Galileon simulations [Zu et al. 2013]

Map to redshift space:

*SHOULD* be easily ruled out by our measurements (2.5% accuracy!) but modified gravity simulations needed for a quantitative comparison

Oslo: Beyond ΛCDM

Thursday, January 15, 2015

Beth Reid

Mandelbaum et al. 2012

Example I1: Combining galaxy-galaxy lensing and galaxy clustering

Oslo: Beyond ΛCDM

Lensing Clustering

Thursday, January 15, 2015

Beth Reid

Mandelbaum et al. 2012

Example I1: Combining galaxy-galaxy lensing and galaxy clustering

Oslo: Beyond ΛCDM

• Focus on R ≳ 3 h-1 Mpc, where

cross-correlation coefficient ≈ 1 (corrections perturbative)

• Constrains σ8 Ωm0.6
• Should also be interesting for

modified gravity models

lensing + clustering WMAP ΛCDM

Thursday, January 15, 2015

Beth Reid

Leclercq & Wandelt, arXiv:1410.1546

Example I1I: Bayesian inference for LSS

Oslo: Beyond ΛCDM

• Jointly constrains 3d density field, power

spectrum, and galaxy biases

• What else can we learn from this approach?
• See also Ata, Kituara, and Muller

Thursday, January 15, 2015

Conclusions

• Linear regime LSS probes are generally consistent with

Planck ΛCDM prediction, though intriguing “tensions” exist (Ly-α BAO; σ8 from lensing/RSD/clusters at low redshift)

• Mildly nonlinear regime offers more signal to noise,

requires simulations for modeling; relatively unexplored

Beth Reid Oslo: Beyond ΛCDM

Thursday, January 15, 2015