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COMING HOME

COMING HOME. Michael S. Turner Kavli Institute for Cosmological Physics The University of Chicago. Some Cosmological Observations from Afar. No Chinks in “The New Cosmology”. WMAP + SDSS + 2dF + HST Key Project + DASI + ACBAR + CBI + t 0 + SNe … Smaller error bars, consistency remains

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COMING HOME

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  1. COMING HOME Michael S. Turner Kavli Institute for Cosmological Physics The University of Chicago

  2. Some Cosmological Observations from Afar

  3. No Chinks in “The New Cosmology” • WMAP + SDSS + 2dF + HST Key Project + DASI + ACBAR + CBI + t0 + SNe … • Smaller error bars, consistency remains • σ(n): 0.1 to 0.02; σ(Ω0): 0.03 to 0.01; σ(w): 0.2 to 0.1 • Hubble constant has been constant for 5 years! H0 = 72 ± 7 km/s/Mpc • Looking better than ever – almost ready for a real name! (i.e., CDM + Dark Energy + Inflation)

  4. Precision Cosmology is Harder than Theorists’ projections • “Bits & bites” • l = 2 to 5 • Optical depth: τ = 0.17 to 0.09

  5. Serious testing of Inflation has begun Key Predictions • Flat Universe • Almost scale-invariant, Gaussian perturbations: |(n-1)| ~ 0.1 and |dn/dlnk| ~ 0.001 • Gravity waves: spectrum, but not amplitude predicted Key Results • Ω0 = 1.0 ± 0.01 • (n-1) = 0.96 ± 0.017*; dn/dlnk = -0.1 ± 0.05; no evidence for nonGaussianity • r < 0.55 (95% cl)* *Depends significantly upon the priors assumed

  6. Cosmic AccelerationDark Energy • Evidence for cosmic acceleration has gotten stronger (HST, CFHTLS, Essence, WMAP, XMM/Chandra…) • Still no understanding – “theorists continue to explore phase space” • No evidence that dark energy is not the energy of the quantum vacuum • w = -1 ± 0.1 (from ± 0.2); no evidence for time variation • Very significant probes on the horizon: • JDEM, LSST, …

  7. Loose Ends • Precision test (few percent) using baryon density: BBN (D/H) vs. CMB (odd/even) unrealized • Consistency of BBN light element predictions (He – D – Li tension) • σ8: lack of consistency • Cosmic variation of α • Excess power at l ~ 2000 • “LSND 4th neutrino” • DAMA, e+ excess, …

  8. What Do We Really Know About Cosmic Acceleration Charles A. Shapiro & Michael S. Turner, astro-ph/0512586

  9. Much of What We Know About Cosmic Acceleration Traces to Model Assumptions (ΛCDM, wCDM) • ΛCDM, wCDM are much better fits than models w/o “dark energy” (CDM or OCDM) • … but, the acceleration history is fixed: recent acceleration, past deceleration • In addition, the correctness of Friedmann equation is assumed (what if gravity theory is part of the solution?)

  10. Assumptions & Inputs • Metric theory of gravity with Robertson-Walker metric • “Friedmannless” analysis • Reiss et al’s Gold Set of Supernovae (adding CFHT Legacy doesn’t change things much) • Flat Universe (can be relaxed – more later) • Piecewise constant acceleration histories • Principal component analysis for q(z)

  11. Robust Conclusions • Universe may not be accelerating today: Model with deceleration since z = 0.3 is acceptable at 10% cl • Very strong evidence that Universe once accelerated (5σ) (from best determined mode) • Strong evidence that q(z) was larger in the past (other well determined modes) • Weak evidence that Universe decelerated in the past

  12. Deceleration Redshift 6 Most Well Determined Principal Components

  13. 2 Best Determined Modes ΛCDM

  14. Without Friedmann Equation Best Evidence for Flatness is Lost (i.e., CMB Anisotropy) • Might be able to determine spatial curvature independently: dV = r2drdΩ / [1 - kr2]1/2 r(z) = coordinate distance to object with redshift z |k|-1/2 = curvature radius • Determine r and dr (e.g., SNe) and dV (e.g. number counts), infer k

  15. My List of Burning Issues • Cosmic Acceleration/Dark Energy: “Most Profound Mystery in all of Science” • Dark Matter: 3 pronged approach – space, accelerators, and underground expt’s – the prize is within sight! • Testing the predictions of inflation – inflation is knocking at the door to become part of “standard cosmology” • Using the consistency and crosschecks now afforded by precision cosmological data (BBN, SDSS/2dF, WMAP, SNe…) to test General Relativity in new regimes

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