Cosmology Surveys a nonWHT talk Dark Energy science
- Slides: 31
Cosmology Surveys (a non-WHT talk) - Dark Energy science and beyond - Imaging surveys - Spectroscopic surveys Ofer Lahav University College London
“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: H 2(z) = H 20 [ M (1+z) 3 + DE (1+z) 3 (1+w) ] (flat)
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
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?
Standard rulers
Baryonic Acoustic Oscillations Comving distance SDSS Luminous Red Galaxies Density fluctuations z=0. 5 Harmonic l CMB WMAP Temperature fluctuations z=1000
Probing the Geometry of the Universe with Supernovae Ia ‘Union’ SN Ia sample (Kowalski et al. 2008)
In 3 Dimensions Massey et al. 2007
Galaxy Surveys 2010 -2020 Photometric surveys: DES, Pan-STARRS, HSC, Skymapper, PAU, LSST, Euclid (EIC), JDEM(SNAP-like), … Spetroscopic surveys: Wiggle. Z, BOSS, Big. BOSS, hetdex, WFMOS/Sumire, Euclid (NIS) JDEM (Adept-like), SKA, …
Photometric redshifts • Probe strong spectral features (e. g. 4000 break) • Template vs. Training methods z=0. 1 z=3. 7
Mega. Z-LRG Photoz scatter of 0. 04 • Input: 10, 000 galaxies with spectra • Train a neural network • ANNz, Collister & Lahav 2004 • Output: 1, 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!
Neutrino mass from Mega. Z-LRG Total mass < 0. 3 e. V (95% CL) Thomas, Abdalla & OL (2009) 0911. 5291
The Dark Energy http: //www. darkenergysurvey. org
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: CTIO Observatorio Nacional, CBPF, Universidade Federal do Rio de Janeiro, Universidade Federal do Rio Grande do Sul
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 4 m Telescope at the Cerro Tololo Inter-American Observatory (CTIO)
The 5 lenses are now being polished C 2 C 1 Polishing & coating coordinated by UCL (with 1. 7 M STFC funding)
Euclid Imaging Surveys Wide Survey: Extragalactic sky (20, 000 deg 2 = 2 p sr) • Visible: Galaxy shape measurements to RIZAB ≤ 24. 5 (AB, 10σ) at 0. 16” FWHM, yielding 30 -40 resolved galaxies/amin 2, with a median redshift z~ 0. 9 • NIR photometry: Y, J, H ≤ 24 (AB, 5σ PS), yielding photo-z’s errors of 0. 03 -0. 05(1+z) with ground based complement (Pan. Starrs-2, DES. etc) • Concurrent with spectroscopic survey Deep Survey: 40 deg 2 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. Wide Extragalactic 20, 000 deg 2 Galactic Plane Deep ~40 deg 2
Spectroscopic Surveys SDSS 2 MRS Cf. A 2 d. FGRS
SUBARU: the ups and downs of WFMOS and the hopes for SUMIRE
Redshift Distortion as a test of Modified Gravity Guzzo et al. 2008
Big. BOSS: The Ground-Based Stage IV BAO Experiment 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 Fo. M) 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 • http: //bigboss. lbl. gov/
Cosmology Surveys summary * Goal: Dark Energy parameters to a few % level • Both imaging and spectroscopy surveys are essential • Is a BAO survey with a 4 m feasible? • Non-DE science with DE surveys (e. g. Neutrino mass, galaxy evolution, MW structure, QSOs)
THE END
Planned photometric and spectroscopic surveys
The Dark Energy problem: 10, 90 or 320 years old? The weak field limit of GR: F = -GM/r 2 + /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)
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
DES Forecasts: Power of Multiple Techniques w(z) =w 0+wa(1–a) 68% CL Fo. M factor 4. 6 tigther compared to near term projects
The Chequered History of the Cosmological 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?
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
Euclid - impact on Cosmology Δwp Current+WMAP ΔWa ΔΩm ΔΩΛ ΔΩb Δσ8 Δns Δh DE Fo. M 0. 13 - 0. 015 0. 0015 0. 026 0. 013 ~10 - - 0. 008 - 0. 0007 0. 05 0. 007 - 0. 03 0. 17 0. 006 0. 04 0. 012 0. 013 0. 02 0. 1 180 Imaging Probes 0. 018 0. 15 0. 004 0. 02 0. 007 0. 0009 0. 014 0. 07 400 Euclid 0. 016 0. 13 0. 003 0. 012 0. 005 0. 003 0. 006 0. 020 500 0. 01 0. 066 0. 0008 0. 003 0. 0004 0. 0015 0. 003 0. 002 1500 13 >15 13 5 4 17 4 7 150 Planck Weak Lensing Euclid +Planck Factor Gain 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. 04 e. V 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
- Dark matter and dark energy presentation
- In a dark dark town
- Cosmology
- Critical density cosmology
- Scale factor cosmology
- Tomislav prokopec
- Definition of cosmology
- Cosmology
- Crossover cosmology
- Concordance model of cosmology
- Cosmology
- Cosmology
- Newton cosmology
- Cosmology
- Intro to cosmology
- Jain geography universe
- Talk, read, talk, write resources
- Amateurs discuss tactics professionals discuss logistics
- The words use are not
- My favorite subject is p.e
- Energy energy transfer and general energy analysis
- Energy energy transfer and general energy analysis
- Cube of stabilized dark energy
- Dma dark energy
- Hand safety toolbox
- Lanham act survey
- Snap surveys
- Real eyes surveys
- Survey vs observational study
- Rebuttal surveys
- Security survey is also known as.
- Survey the literature