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Cosmology Surveys (a non-WHT talk)

Cosmology Surveys (a non-WHT talk). Ofer Lahav University College London. D a rk Energy science and beyond Imaging surveys - Spectroscopic surveys. “Evidence” for Dark Energy. Observational data Type Ia Supernovae Galaxy Clusters Cosmic Microwave Background

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Cosmology Surveys (a non-WHT talk)

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  1. Cosmology Surveys(a non-WHT talk) Ofer Lahav University College London • Dark Energy science and beyond • Imaging surveys • - Spectroscopic surveys

  2. “Evidence” for Dark Energy Observational data • Type Ia Supernovae • Galaxy Clusters • Cosmic Microwave Background • Large Scale Structure • Gravitational Lensing • Integrated Sachs-Wolfe Physical effects: • Geometry • Growth of Structure Both depend on the Hubble expansion rate: H2(z) = H20 [M (1+z) 3 + DE (1+z) 3 (1+w) ] (flat)

  3. Dark Energy Pre-SNIa • Peebles (1984) advocated Lambda • APM result for low matter density (Efstathiou et al. 1990) • Baryonic fraction in clusters (White et al. 1993) • The case for adding Lambda (Ostriker & Steinhardt 1995) • Others… Calder & OL, Physics World, Jan 2010

  4. What will be the next paradigm shift? • Vacuum energy (cosmological constant)? • Dynamical scalar field? • w=p/ • for cosmological constant: w = -1 • Manifestation of modified gravity? • Inhomogeneous Universe? • What if cosmological constant after all? • Multiverse - Landscape? • The Anthropic Principle?

  5. Standard rulers

  6. Baryonic Acoustic Oscillations Comving distance Harmonic l SDSS Luminous Red Galaxies Density fluctuations CMB WMAP Temperature fluctuations z=0.5 z=1000

  7. Probing the Geometryof the Universe with Supernovae Ia ‘Union’ SN Ia sample (Kowalski et al. 2008)

  8. In 3 Dimensions Massey et al. 2007

  9. Galaxy Surveys2010-2020 Photometric surveys: DES, Pan-STARRS, HSC, Skymapper, PAU, LSST, Euclid (EIC), JDEM(SNAP-like), … Spetroscopic surveys: WiggleZ, BOSS, BigBOSS, hetdex, WFMOS/Sumire, Euclid (NIS) JDEM (Adept-like), SKA, …

  10. Photometric redshifts z=0.1 z=3.7 • Probe strong spectral features (e.g. 4000 break) • Template vs. Training methods

  11. MegaZ-LRG Photoz scatter of 0.04 • Input: 10,000 galaxies with spectra • Train a neural network • ANNz, Collister & Lahav 2004 • Output: 1,000,000 photo-z • Collister, Lahav et al. 2007 • Update using 6 photo-z methods • *Abdalla et al. 2009 3 (Gpc/h)3: the largest ever galaxy redshift survey!

  12. Neutrino mass from MegaZ-LRG Total mass < 0.3 eV (95% CL) Thomas, Abdalla & OL (2009) 0911.5291

  13. The Dark Energy http://www.darkenergysurvey.org

  14. The DES Collaboration an international collaboration of ~100 scientists from ~20 institutions US: Fermilab, UIUC/NCSA, University of Chicago, LBNL, NOAO, University of Michigan, University of Pennsylvania, Argonne National Laboratory, Ohio State University, Santa-Cruz/SLAC Consortium UK Consortium: UCL, Cambridge, Edinburgh, Portsmouth, Sussex, Nottingham Spain Consortium: CIEMAT, IEEC, IFAE Brazil Consortium: Observatorio Nacional, CBPF,Universidade Federal do Rio de Janeiro, Universidade Federal do Rio Grande do Sul CTIO

  15. The Dark Energy Survey (DES) • Proposal: • Perform a 5000 sq. deg. survey of the southern galactic cap • Measure dark energy with 4 complementary techniques • New Instrument: • Replace the PF cage with a new 2.2 FOV, 520 Mega pixel optical CCD camera + corrector • Time scale: • Instrument Construction 2008-2011 • Survey: • 525 nights during Oct.–Feb. 2011-2016 • Area overlap with SPT SZ survey and VISTA VHS Use the Blanco 4m Telescope at the Cerro Tololo Inter-American Observatory (CTIO)

  16. The 5 lenses are now being polished C2 C1 Polishing & coating coordinated by UCL (with 1.7M STFC funding)

  17. Wide Extragalactic 20,000 deg2 Galactic Plane Deep ~40 deg2 Euclid Imaging Surveys • Wide Survey: Extragalactic sky (20,000 deg2 = 2p sr) • Visible: Galaxy shape measurements to RIZAB ≤ 24.5 (AB, 10σ) at 0.16” FWHM,yielding 30-40 resolved galaxies/amin2, with a median redshift z~ 0.9 • NIR photometry: Y, J, H ≤ 24 (AB, 5σ PS), yielding photo-z’s errors of0.03-0.05(1+z) with ground based complement (PanStarrs-2, DES. etc) • Concurrent with spectroscopic survey • Deep Survey:40 deg2 at ecliptic poles • Monitoring of PSF drift (40 repeats at different orientations over life of mission) • Produces +2 magnitude in depth for both visible and NIR imaging data. • Possible additional Galactic surveys: • Short exposure Galactic plane • High cadence microlensing extra-solar planet surveys • could be easily added within Euclid mission architecture.

  18. Spectroscopic Surveys SDSS 2MRS CfA 2dFGRS

  19. SUBARU:the ups and downs of WFMOSand the hopes for SUMIRE

  20. Redshift Distortion as a test of Modified Gravity Guzzo et al. 2008

  21. BigBOSS: The Ground-Based Stage IV BAO Experiment http://bigboss.lbl.gov/ A new 5000-fiber R=5000 spectrograph covering a 3-degree diameter field will measure BAO and redshift space distortions in the distribution of galaxies and hydrogen gas spanning redshifts from 0.2 < z < 3.5. The Dark Energy Task Force figure of merit (DETF FoM) for this experiment is expected to be equal to that of a JDEM mission for BAO with the lower risk and cost typical of a ground-based experiment

  22. Cosmology Surveys - summary * Goal: Dark Energy parameters to a few % level Both imaging and spectroscopy surveys are essential Is a BAO survey with a 4m feasible? Non-DE science with DE surveys (e.g. Neutrino mass, galaxy evolution, MW structure, QSOs)

  23. THE END

  24. Planned photometric and spectroscopic surveys

  25. The Dark Energy problem: 10, 90 or 320 years old? The weak field limit of GR: F = -GM/r2 + /3 r X * “I have now explained the TWO principle cases of attraction… which is very remarkable” Isaac Newton, Principia (1687) Lucy Calder & OL A&G Feb 08 issue http://www.star.ucl.ac.uk/~lahav/CLrev.pdf (revised)

  26. Dark Energy Science Program Four Probes of Dark Energy • Galaxy Clusters • clusters to z>1 • SZ measurements from SPT • Sensitive to growth of structure and geometry • Weak Lensing • Shape measurements of 300 million galaxies • Sensitive to growth of structure and geometry • Large-scale Structure • 300 million galaxies to z = 1 and beyond • Sensitive to geometry • Supernovae • 15 sq deg time-domain survey • ~3000 well-sampled SNe Ia to z ~1 • Sensitive to geometry Plus QSOs, Strong Lensing, Milky Way, Galaxy Evolution

  27. w(z) =w0+wa(1–a) 68% CL DES Forecasts: Power of Multiple Techniques FoM factor 4.6 tigther compared to near term projects

  28. The Chequered History of theCosmological Constant  * The old CC problem: Theory exceeds observational limits on  by 10120 ! * The new CC problem: Why are the amounts of Dark Matter and Dark Energy so similar?

  29. Photo-z –Dark Energy cross talk • Approximately, for a photo-z slice: (w/ w) = 5 (z/ z) = 5 (z/z) Ns-1/2 => the target accuracy in w and photo-z scatter z dictate the number of required spectroscopic redshifts Ns =105-106

  30. Euclid - impact on Cosmology • Euclid Imaging will challenge all sectors of the cosmological model: • Dark Energy: wp and wa with an error of 2% and 13% respectively (no prior) • Dark Matter: test of CDM paradigm, precision of 0.04eV on sum of neutrino masses (with Planck) • Initial Conditions: constrain shape of primordial power spectrum, primordial non-gaussianity • Gravity: test GR by reaching a precision of 2% on the growth exponent  (dlnm/dlnam) • Uncover new physics and Map LSS at 0<z<2: Low redshift counterpart to CMB surveys

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