cosmology with spectroscopic and photometric redshift surveys
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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!
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