Cosmology with Spectroscopic and Photometric Redshift Surveys

Ofer Lahav Department of Physics and Astronomy University College London

• The post-2dF/SDSS/WMAP3 universe• The 2MASS Redshift Survey• The Photo-z MegaZ-LRG• The Dark Energy Survey

Cosmology with Spectroscopic and Photometric Redshift Surveys

Ofer Lahav Department of Physics and Astronomy University College London

• The post-2dF/SDSS/WMAP3 universe• The 2MASS Redshift Survey• The Photo-z MegaZ-LRG• The Dark Energy Survey

Cosmology in 1986 Galaxy redshift surveys of thousands of

galaxies (CfA1, IRAS) CMB fluctuations not detected yet Peculiar velocities popular (7S) “Standard Cold Dark Matter” m = 1, =0

H0 = 50 km/sec/Mpc = 1/(19.6 Gyr)

Redshift Surveys

The evolution of the Cosmic Web in the past 20 years

CfA Great Wall

SDSS

Great Attractor 2dFGRS

2dFGRS PhD students & collaborators

Spectral classification (PCA): S. Folkes, S. Ronen, D. Madgwick

Biasing from 2dF+CMB: S. Bridle

Neutrino mass: O. Elgaroy

Wiener Reconstruction: P. Erdogdu Stochastic Biasing: V. Wild

Testing the halo model: A. Collister

From 2dF+CMB (6 parameter fit): m=0.23 §0.02

Cole et al. 2005

WMAP3

m = 0.24 +-0.04 8 = 0.74 +-0.06 n = 0.95 +-0.02 = 0.09 +-0.03

FF

2MASS Galactic chart 2MASS Galactic chart (Tom Jarrett)(Tom Jarrett)

2MASS and follow-ups

• 2MASS: all sky, 1.5M galaxies (Ks < 13.5)

• 2MRS: all sky, 25K redshifts (Ks <11.25)

• 6dF (Southern hemisphere): 150K redshifts (Ks < 12.75)

and 15K Dn-sigma distances

2MRS Dipole directions

Erdogdu et al. 2005

Dipoles in the Local Group Frame

12o @ 50 Mpc/h

21o @ 130 Mpc/h

m0.6 /bL = 0.40+- 0.10

Erdogdu, Huchra, Lahav et al.,Astro-ph/0507166

Number weighed Flux weighted

Dipole from X-ray clusters

Kocevski, Mullis & Ebeling, astro-ph/0403275

Shapley

Wiener Reconstruction of density and velocity fields

Erdogdu, OL, Huchra et al

Photometric redshift

• Probe strong spectral features (4000 break)

• Difference in flux through filters as the galaxy is redshifted.

ANNz - Artificial Neural Network

Output:redshift

Input:magnitudes

Collister & Lahav 2004http://www.star.ucl.ac.uk/~lahav/annz.html

z = f(m,w)

Example: SDSS data (ugriz; r < 17.77)

ANNz (5:10:10:1) HYPERZ

Collister & Lahav 2004

Padmanabhan et alAstro-ph/0605302

Blake, Collister, Bridle, LahavAstro-ph/0605303

LRG photo-z

Clustering on Gpc scale

*Training on ~13,000 2SLAQ*Generating with ANNz Photo-z for ~1,000,000 LRGs MegaZ-LRG

z = 0.046

Collister, Lahav, Blake et al.

photo-z bins

Collister et al.

Clustering in photo-z space

Angular power spectravary 4 parameters

Non-linear P(k)

Linear P(k)

Minimum fitted

multipole

Cosmological parameter fits separate photo-z slices

Marginalize over: Fix:

Best fit - 1 slice

Best fit - all slices

Cosmology from LRG photo-z(Blake et al.)

.

b/ m = 0.14+-0.04 (cf. 0.18 +- 0.01 from WMAP3)m = 0.27+-0.04 (cf. 0.24+-0.03 from WMAP3)

Excess Power on Large Scales?

Blake et al. 06 Padmanabhan et al. 06

The origin of excess power

• Photo-z systematics?• Window functions?• Cosmic variance?• Large scale redshift distortion?• Large scale biasing?• Gauge transformations?• Modified early universe physics?

Through the history of the expansion rate:

H2(z) = H20 [M (1+z) 3 + DE (1+z) 3 (1+w) ] (flat Universe)

matter dark energy (constant w) P = w Comoving distance r(z) = dz/H(z) Standard Candles dL(z) = (1+z) r(z) Standard Rulers dA(z) = (1+z)1 r(z) Standard Population (volume) dV/dzd = r2(z)/H(z) The rate of growth of structure also determined by H(z) and by

any modifications of gravity on large scales

Probing Dark Matter & Dark Energy

2015

CMB WMAP 2/3 WMAP 6 yrPlanck Planck 4yr

Clusters AMISZA

APEXAMIBA

SPTACT

DES

SupernovaePan-STARRS

DES LSSTJDEM/SNAP

CFHTLSCSP

SpectroscopyATLAS

SKAFMOS KAOSSDSS

Imaging CFHTLSATLAS KIDS

DESVISTA JDEM/

SNAP

LSST SKA

Pan-STARRSSDSS

SUBARU

Surveys to measure Dark Energy

2005

20152005 2010

2010

Dark EnergyDark EnergyTask ForceTask Force

Rocky Kolb et al.

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

Cost: $20M

Sources of uncertainties

• Cosmological (parameters and priors)• Astrophysical (e.g. cluster M-T, biasing) • Instrumental (e.g. “seeing”)

Dark Energy Survey Collaboration

Fermilab- Camera, Survey Planning, and SimulationsU Illinois- Data Management, Data Acquisition, SPTU Chicago- SPT, Simulations, Corrector

LBNL- CCD DetectorsCTIO- Telescope & Camera Operations

Spain: Barcelona, Madrid – Electronics, SimulationsUK: UCL, Portsmouth, Cambridge, Edinburgh – Optics, Science Analysis

The Dark Energy Survey UK Consortium (I) PPARC funding: O. Lahav (PI), P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller (UCL), R. Nichol (Portsmouth), G. Efstathiou, R. McMahon, W. Sutherland (Cambridge) J. Peacock (Edinburgh) Submitted a proposal to PPARC in February 2005 requesting £ 1.5 M

for the fabrication and testing of the optical corrector lenses. In March 2006, PPARC Council announced that it “will seek participation in DES”.

(II) SRIF3 funding: R. Nichol, R. Crittenden, R. Maartens, W. Percival (ICG Portsmouth) K. Romer, A. Liddle (Sussex)

Partial funding of the glass blanks for the UCL DES optical work

These scientists will work together through the UK DES Consortium. Other DES proposals are under consideration by US and Spanish funding agencies.

Dark Energy Survey Instrument

3.5 meters

CameraFilters

Optical Lenses

ScrollShutter

1.5 meters

New Prime Focus Cage, Camera, and Corrector for the Blanco 4m Telescope 500 Megapixels, 0.27”/pixel Project cost: ~20M$ (incl. labor)

VDES proposal

DES (griz) DES+VISTA(JK)

Spectroscopic Redshift Training Sets for DES

Redshift Survey Overlap with DES Number of Redshifts Overlapping DES

Sloan Digital Sky Survey SouthernEquatorial Stripe (Stripe 82)

70,000, r<20median z=0.1–0.6 depending on the sample

2dF Galaxy Redshift Survey

Most of SGP strip and SGP random fields

90,000, bJ<19.45

median z = 0.1

VIMOS VLT Deep Survey 3 fields at RA/Dec = 2217+00, 0226–04, 0332–28

~60,000, IAB<24

median z ~ 0.8

DEEP2 Redshift Survey 2 fields at RA/Dec = 2330+00, 0230+00

~30,000, RAB<24.1

median z ~ 1

P5 – April 20, 2006

DES Forecasts: Power of Multiple Techniques

Frieman, Ma, Weller, Tang, Huterer, etal

Assumptions:Clusters: 8=0.75, zmax=1.5,WL mass calibration(no clustering)

BAO: lmax=300WL: lmax=1000(no bispectrum)

Statistical+photo-z systematic errors only

Spatial curvature, galaxy biasmarginalized

Planck CMB prior

w(z) =w0+wa(1–a) 68% CL

geometric

geometric+growth

Clustersif 8=0.9

Baryon Wiggles as Standard Rulers(for $60M, or less?)

Summary

Many observations support the -CDM model, but…

- What is the Dark Matter? - What is the Dark Energy? - Why are their amounts similar?

If in 10 years it turns out that w=-1 to within 1%, then what??

New Physics? The Anthropic Principle? Multiverse?

Globalisation and the New Astronomy

One definition of globalisation: “A decoupling of space and time -

emphasising that with instantaneous communications, knowledge and culture can be shared around the world simultaneously.”

Globalisation and the New Astronomy

How is the New Astronomy affected by globalisation? Free information (WWW), big international projects, numerous conferences, telecons… Recall the Cold War era: Hot Dark Matter/top-down (Russia) vs. Cold Dark Matter/bottom-up (West)

Is the agreement on the `concordance model’ a product of globalisation?

Happy Birthday,Bernard!