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 –σ(n): 0.1 to 0.02; σ(Ω 0 ): 0.03 to 0.01; σ(w): 0.2 to 0.1 Hubble constant has been constant for 5 years! H 0 = 72 ± 7 km/s/Mpc Looking better than ever – almost ready for a real name! (i.e., CDM + Dark Energy + Inflation)

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

Serious testing of Inflation has begun Key Predictions 1.Flat Universe 2.Almost scale-invariant, Gaussian perturbations: |(n-1)| ~ 0.1 and |dn/dlnk| ~ Gravity waves: spectrum, but not amplitude predicted Key Results 1.Ω 0 = 1.0 ± (n-1) = 0.96 ± 0.017*; dn/dlnk = -0.1 ± 0.05; no evidence for nonGaussianity 3.r < 0.55 (95% cl)* *Depends significantly upon the priors assumed

Cosmic Acceleration Dark 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, …

Loose Ends 1.Precision test (few percent) using baryon density: BBN (D/H) vs. CMB (odd/even) unrealized 2.Consistency of BBN light element predictions (He – D – Li tension) 3.σ 8 : lack of consistency 4.Cosmic variation of α 5.Excess power at l ~ “LSND 4 th neutrino” 7.DAMA, e + excess, …

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

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?)

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)

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

6 Most Well Determined Principal Components Deceleration Redshift

ΛCDM 2 Best Determined Modes

Without Friedmann Equation Best Evidence for Flatness is Lost (i.e., CMB Anisotropy) Might be able to determine spatial curvature independently: dV = r 2 drdΩ / [1 - kr 2 ] 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

My List of Burning Issues 1.Cosmic Acceleration/Dark Energy: “Most Profound Mystery in all of Science” 2.Dark Matter: 3 pronged approach – space, accelerators, and underground expt’s – the prize is within sight! 3.Testing the predictions of inflation – inflation is knocking at the door to become part of “standard cosmology” 4.Using the consistency and crosschecks now afforded by precision cosmological data (BBN, SDSS/2dF, WMAP, SNe…) to test General Relativity in new regimes