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 H 0 = 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 =  8 = n =  =

Are the 2dFGRS superclusters anomalous? Baugh et al., Erdogdu et al., Murphy & OL  Abell clusters 77 groups (>8)  Abell clusters  groups (>8)

F 2MASS Galactic chart (Tom Jarrett)

2MASS and follow-ups 2MASS: all sky, 1.5M galaxies (K s < 13.5) 2MRS: all sky, 25K redshifts (K s <11.25) 6dF (Southern hemisphere): 150K redshifts (K s < 12.75) and 15K Dn-sigma distances

2MRS Dipole directions Erdogdu et al. 2005

Dipoles in the Local Group Frame Mpc/h Mpc/h  m 0.6 /b L = Erdogdu, Huchra, Lahav et al., Astro-ph/ Number weighed Flux weighted

Dipole from X-ray clusters Kocevski, Mullis & Ebeling, astro-ph/ 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 z = f(m,w)

Example: SDSS data (ugriz; r < 17.77) ANNz (5:10:10:1) HYPERZ Collister & Lahav 2004

Photo-z for SDSS: comparison

Padmanabhan et al Astro-ph/ Blake, Collister, Bridle, Lahav Astro-ph/ 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 = 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

Baryon oscillations? Divide out a “wiggle-free” fit and stack spectra

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 = (cf from WMAP3)  m = (cf 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: H 2 (z) = H 2 0 [  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 d L (z) = (1+z) r(z)  Standard Rulers d A (z) = (1+z)  1 r(z)  Standard Population (volume) dV/dzd  = r 2 (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 CMBWMAP 2/3WMAP 6 yr PlanckPlanck 4yr ClustersAMI SZA APEX AMIBA SPT ACT DES Supernovae Pan-STARRS DESLSST JDEM/ SNAP CFHTLS CSP Spectroscopy ATLAS SKAFMOSKAOS SDSS ImagingCFHTLS ATLASKIDS DES VISTAJDEM/ SNAP LSSTSKA Pan-STARRS SDSS SUBARU Surveys to measure Dark Energy

Dark Energy Task Force Dark Energy Task 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 deg 2 camera on the CTIO Blanco 4m Construction Survey (~525 nights) 5000 deg 2 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 Filters Optical Lenses Scroll Shutter 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 SurveyOverlap with DESNumber of Redshifts Overlapping DES Sloan Digital Sky SurveySouthernEquatorial Stripe (Stripe 82) 70,000, r<20 median z=0.1–0.6 depending on the sample 2dF Galaxy Redshift Survey Most of SGP strip and SGP random fields 90,000, b J <19.45 median z = 0.1 VIMOS VLT Deep Survey3 fields at RA/Dec = , 0226–04, 0332– 28 ~60,000, I AB <24 median z ~ 0.8 DEEP2 Redshift Survey2 fields at RA/Dec = , ~30,000, R AB <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, z max =1.5, WL mass calibration (no clustering) BAO: l max =300 WL: l max =1000 (no bispectrum) Statistical+photo-z systematic errors only Spatial curvature, galaxy bias marginalized Planck CMB prior w(z) =w 0 +w a (1–a) 68% CL geometric geometric+ growth Clusters if  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?

Globalisation and the New Astronomy  Independent communities are beneficial, but eventually they should talk to each other!

Happy Birthday, Bernard!