Transcript The 2dF Galaxy Redshift Survey

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
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
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
SDSS
CfA Great Wall
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
F
2MASS Galactic chart (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
Number weighed
Flux weighted
m0.6 /bL = 0.40+- 0.10
12o @ 50 Mpc/h
21o @ 130 Mpc/h
Erdogdu, Huchra, Lahav et al.,
Astro-ph/0507166
Dipole from X-ray clusters
Shapley
Kocevski, Mullis
& Ebeling,
astro-ph/0403275
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
z = f(m,w)
Input:
magnitudes
Collister & Lahav 2004
http://www.star.ucl.ac.uk/~lahav/annz.html
Output:
redshift
Example: SDSS data (ugriz;
r < 17.77)
ANNz (5:10:10:1)
Collister & Lahav 2004
HYPERZ
Clustering on
Gpc scale
LRG photo-z
Padmanabhan et al
Astro-ph/0605302
Blake, Collister, Bridle, Lahav
Astro-ph/0605303
*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 spectra
vary 4 parameters
Non-linear P(k)
Linear P(k)
Minimum fitted
multipole
Cosmological parameter fits
separate photo-z slices
Marginalize over:
Best fit - all
slices
Best fit - 1 slice
Fix:
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
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Photo-z systematics?
Window functions?
Cosmic variance?
Large scale redshift distortion?
Large scale biasing?
Gauge transformations?
Modified early universe physics?
Probing Dark Matter & Dark Energy
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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
Surveys to measure Dark Energy
Imaging
CFHTLS SUBARU
SDSS ATLAS KIDS
Spectroscopy
2015
2010
2005
DES
LSST
VISTA
Pan-STARRS
JDEM/
SNAP
FMOS
KAOS
SKA
SKA
SDSS ATLAS
Supernovae CSP
CFHTLS
Clusters
AMI
DES
LSST
Pan-STARRS
JDEM/
SNAP
APEX SPT
DES
SZA AMIBA ACT
CMB
WMAP 2/3
WMAP 6 yr
Planck
2005
Planck 4yr
2010
2015
Dark Energy
Task Force
Rocky Kolb et al.
The Dark Energy Survey
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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: $20M
Sources of uncertainties
• Cosmological (parameters and priors)
• Astrophysical (e.g. cluster M-T, biasing)
• Instrumental (e.g. “seeing”)
Dark Energy Survey Collaboration
Fermilab- Camera, Survey Planning, and Simulations
U Illinois- Data Management, Data Acquisition, SPT
U Chicago- SPT, Simulations, Corrector
LBNL- CCD Detectors
CTIO- Telescope & Camera Operations
Spain: Barcelona, Madrid – Electronics, Simulations
UK: UCL, Portsmouth, Cambridge, Edinburgh –
Optics, Science Analysis
The Dark Energy Survey UK Consortium
(I) PPARC funding:
O. Lahav (PI), P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller (UCL),
R. Nichol (Portsmouth), G. Efstathiou, R. McMahon, W. Sutherland (Cambridge)
J. Peacock (Edinburgh)
Submitted a proposal to PPARC in February 2005 requesting £ 1.5 M
for the fabrication and testing of the optical corrector lenses. In March
2006, PPARC Council announced that it “will seek participation in DES”.
(II) SRIF3 funding:
R. Nichol, R. Crittenden, R. Maartens, W. Percival (ICG Portsmouth)
K. Romer, A. Liddle (Sussex)
Partial funding of the glass blanks for the UCL DES optical work
These scientists will work together through the UK DES Consortium.
Other DES proposals are under consideration by
US and Spanish funding agencies.
Dark Energy Survey Instrument
3.5 meters
Camera Scroll
Shutter Filters
1.5 meters
Optical Lenses
New Prime Focus Cage, Camera, and
Corrector for the Blanco 4m Telescope
500 Megapixels, 0.27”/pixel
Project cost: ~20M$ (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 70,000, r<20
(Stripe 82)
median z=0.1–0.6
depending on the
sample
2dF Galaxy Redshift
Survey
Most of SGP strip and 90,000, bJ<19.45
SGP random fields
median z = 0.1
VIMOS VLT Deep Survey
3 fields at RA/Dec = ~60,000, IAB<24
2217+00, 0226–04, 0332–
median z ~ 0.8
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DEEP2 Redshift Survey
2 fields at RA/Dec
2330+00, 0230+00
= ~30,000, RAB<24.1
median z ~ 1
DES Forecasts: Power of Multiple Techniques
Assumptions:
Clusters:
8=0.75, zmax=1.5,
WL mass calibration
(no clustering)
w(z) =w0+wa(1–a)
68% CL
BAO: lmax=300
WL: lmax=1000
(no bispectrum)
Statistical+photo-z
systematic errors only
Spatial curvature, galaxy bias
marginalized
geometric+
growth
Clusters
if 8=0.9
geometric
Planck CMB prior
Frieman, Ma, Weller, Tang,
Huterer, etal
P5 – April 20, 2006
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!