Cosmology with Spectroscopic and Photometric Redshift Surveys

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Cosmology with Spectroscopic and Photometric
Redshift Surveys

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

• Ofer Lahav
• Department of Physics and Astronomy
• University College London

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Cosmology with Spectroscopic and Photometric
Redshift Surveys

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

• Ofer Lahav
• Department of Physics and Astronomy
• University College London

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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)

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Redshift Surveys
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The evolution of the Cosmic Web in the past 20
years
SDSS
CfA Great Wall
Great Attractor
2dFGRS
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2dFGRS PhD students collaborators
Spectral classification (PCA) S. Folkes, S.
Ronen, D. Madgwick Biasing from 2dFCMB S.
Bridle Neutrino mass O. Elgaroy Wiener
Reconstruction P. Erdogdu Stochastic
Biasing V. Wild Testing the halo model A.
Collister
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From 2dFCMB (6 parameter fit) ?m0.23 0.02
Cole et al. 2005
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WMAP3
?m 0.24 -0.04 ?8 0.74 -0.06 n
0.95 -0.02 ? 0.09 -0.03
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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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F
2MASS Galactic chart (Tom Jarrett)
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2MASS and follow-ups

• 2MASS all sky, 1.5M galaxies (Ks lt 13.5)
• 2MRS all sky, 25K redshifts (Ks lt11.25)
• 6dF (Southern hemisphere)
• 150K redshifts (Ks lt 12.75)
• and 15K Dn-sigma distances

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2MRS Dipole directions
Erdogdu et al. 2005
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Dipoles in the Local Group Frame
Flux weighted
Number weighed
?m0.6 /bL 0.40- 0.10
12o _at_ 50 Mpc/h
21o _at_ 130 Mpc/h
Erdogdu, Huchra, Lahav et al., Astro-ph/0507166
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Dipole from X-ray clusters
Shapley
Kocevski, Mullis Ebeling, astro-ph/0403275
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Wiener Reconstruction of density and velocity
fields
Erdogdu, OL, Huchra et al
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Photometric redshift

• Probe strong spectral features (4000 break)
• Difference in flux through filters as the galaxy
  is redshifted.

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ANNz - Artificial Neural Network
z f(m,w)

Output redshift
Input magnitudes
Collister Lahav 2004
http//www.star.ucl.ac.uk/lahav/annz.html
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Example SDSS data (ugriz r lt 17.77)
ANNz (510101)
HYPERZ

Collister Lahav 2004
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Photo-z for SDSS comparison
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Clustering on Gpc scale
LRG photo-z
Padmanabhan et al Astro-ph/0605302 Blake,
Collister, Bridle, Lahav Astro-ph/0605303
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Training on 13,000 2SLAQGenerating with
ANNz Photo-z for 1,000,000 LRGs MegaZ-LRG
?z 0.046
Collister, Lahav, Blake et al.
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photo-z bins
Collister et al.
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Clustering in photo-z space
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Angular power spectra

vary 4 parameters
Non-linear P(k)
Minimum fitted multipole
Linear P(k)
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Baryon oscillations?
Divide out a wiggle-free fit and stack spectra
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Cosmological parameter fits
separate photo-z slices
Marginalize over
Fix
Best fit - all slices
Best fit - 1 slice
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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)
.
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Excess Power on Large Scales?
Blake et al. 06
Padmanabhan et al. 06
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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?

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Probing Dark Matter Dark Energy

• Through the history of the expansion rate
• H2(z) H20 ?M (1z) 3 ?DE (1z) 3 (1w)
  (flat Universe)
• matter
  dark energy (constant w)
• P w ?
• Comoving distance
  r(z) ? dz/H(z)
• Standard Candles
  dL(z) (1z) r(z)
• Standard Rulers
  dA(z) (1z)?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

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Surveys to measure Dark Energy
2015
2010
2005
Imaging
CFHTLS
DES
LSST
SKA
SUBARU
ATLAS
KIDS
VISTA
JDEM/ SNAP
SDSS
Pan-STARRS
2015
2005
2010
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Dark Energy Task Force
Rocky Kolb et al.
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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

Cost 20M
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Sources of uncertainties

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

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Dark Energy Survey Collaboration
Fermilab- Camera, Survey Planning, and
Simulations U Illinois- Data Management, Data
Acquisition, SPT U Chicago- SPT, Simulations,
Corrector LBNL- CCD Detectors CTIO- Telescope
Camera Operations Spain Barcelona, Madrid
Electronics, Simulations UK UCL, Portsmouth,
Cambridge, Edinburgh Optics, Science Analysis
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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.

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Dark Energy Survey Instrument
3.5 meters
Camera
1.5 meters
Scroll Shutter
Filters
Optical Lenses
New Prime Focus Cage, Camera, and Corrector for
the Blanco 4m Telescope 500 Megapixels,
0.27/pixel Project cost 20M (incl.
labor)
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VDES proposal
DES (griz)
DESVISTA(JK)
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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, rlt20 median z0.10.6 depending on the sample
2dF Galaxy Redshift Survey Most of SGP strip and SGP random fields 90,000, bJlt19.45 median z 0.1
VIMOS VLT Deep Survey 3 fields at RA/Dec 221700, 022604, 033228 60,000, IABlt24 median z 0.8
DEEP2 Redshift Survey 2 fields at RA/Dec 233000, 023000 30,000, RABlt24.1 median z 1
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DES Forecasts Power of Multiple Techniques
Assumptions Clusters ?80.75, zmax1.5, WL
mass calibration (no clustering) BAO
lmax300 WL lmax1000 (no bispectrum) Statistica
lphoto-z systematic errors only Spatial
curvature, galaxy bias marginalized Planck CMB
prior
w(z) w0wa(1a) 68 CL

• geometric
• growth

Clusters if ?80.9
geometric
Frieman, Ma, Weller, Tang, Huterer, etal
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Baryon Wiggles as Standard Rulers(for 60M, or
less?)
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Summary

• Many observations support the L-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?

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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.

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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?

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Globalisation and the New Astronomy

• Independent communities are beneficial,
• but eventually they should
• talk to each other!

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• Happy Birthday,
• Bernard!