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Dark Energy Cosmology

Dark Energy Cosmology. Robert Caldwell Dartmouth College. INPE Winter School September 12-16, 2005. galaxy rotation curves. dark matter. Pioneer anomaly. Anderson et al, PRL 81 (1998) 2858. drift of Astronomical Unit. Krasinsky & Brumberg, Cel. Mech. & Dyn. Astro. 90 (2004) 267.

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Dark Energy Cosmology

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  1. Dark Energy Cosmology Robert Caldwell Dartmouth College INPE Winter School September 12-16, 2005

  2. galaxy rotation curves dark matter Pioneer anomaly Anderson et al, PRL 81 (1998) 2858 drift of Astronomical Unit Krasinsky & Brumberg, Cel. Mech. & Dyn. Astro. 90 (2004) 267 drift of Moon from Earth Gravity? a provocative list cosmic acceleration dark energy

  3. Tests of Gravity Einstein Equivalence Principle • Test bodies fall with the same acceleration independently of internal structure or composition (WEP: weak equivalence principle) • The outcome of any local, non-gravitational experiment is independent of velocity of the freely falling reference frame in which it is performed (LLI: local Lorentz invariance) • The outcome of any local, non-gravitational experiment is independent of where or when in the universe it is performed (LPI: local position invariance) Will, gr-qc/0504086 Einstein’s General Relativity is the standard model of gravitation

  4. Tests of Gravity PPN Parameters : (=1 in GR) The amount of non-linearity in gravitational superposition : (=1 in GR) How much curvature is produced by unit rest mass Lunar laser ranging Williams et al, PRL 93 (2004) 261101 Time delay of signals from Cassini spacecraft Bertotti et al, Nature 425 (2003) 374

  5. Tests of Gravity local acceleration of bodies of different composition Eot-Wash: Baessler et al, PRL 83 (1999) 3585 Lunar laser ranging Williams et al, PRL 93 (2004) 261101 Nordtvedt effect: observations of the acceleration of bodies with different gravitational binding energies tests the Strong Equivalence Principle Mass definitions:

  6. Tests of Gravitational Coupling EEP: non-gravitational phenomena independent of cosmic evolution Serendipitous Result Oklo (Gabon) natural fission reaction, 2 Gyrs ago Laboratory Measurements Peik et al, PRL 93 (2004) 170801 Fischer et al, PRL 92 (2004) 230802

  7. Tests of Gravitational Coupling EEP: non-gravitational phenomena independent of cosmic evolution Astrophysical Observations First limit on  Savedoff, Nature 176 (1956) 688 First limit from quasar spectra Bahcall & Salpeter, ApJ 142 (1965) L1677 Webb et al, PRL 87 (2001) 091301 Srianand et al, PRL 92 (2004) 121302 …more published limits possible systematics in baseline lab measurements Ivanchik et al, A&A 440 (2005) 45

  8. Dark Energy There are numerous other proposed models of dark energy. Artistic view of a universe filled by a turbulent sea of dark energy

  9. Dark Energy Ideas Dark Energy - Matter Coupling Amendola et al, ApJ 583 (2003) L53 Dark Energy Solid Bucher & Spergel, PRD 60 (1999) 043505 Chaplygin Gas Kamenshchik et al, PLB 511 (2001) 265 Bulk Pressure of Particle Creation Zimdahl, PRD 61 (2000) 083511 Quantum Effects of a Scalar Field Parker & Vanzella, PRD 69 (2004) 104009 … Dark Energy & Gravity: Non-Minimal Coupling Scalar-Tensor Models GR as an attractor of S-T Theories: Damour & Nordtvedt, PRL 70 (1993) 2217 Perrotta et al, PRD 61 (2000) 023507 Bartolo et al, PRD 61 (2000) 023518 … Modifications of Einstein Gravity Carroll et al, PRD 70 (2004) 043528 …

  10. Dark Energy & Gravity Modification of Einstein Gravity Olmo, gr-qc/0505135,6 Metric Variation of the Action Palatini Variation of the Action The scalar field is non-dynamical. Instead, it is a derived quantity which depends on the local matter density and the potential.

  11. Dark Energy & Gravity Modification of Einstein Gravity also modifies Newtonian Gravity! Constraints on Newtonian potential… Gravitational Constant, G… Plus considerations of cosmic acceleration… …tight restrictions on the form of the gravitational Lagrangian Olmo, gr-qc/0505135,6

  12. Dark Energy The influence of dark energy on the cosmic expansion slows the growth of inhomogeneities in the dark matter and baryons.

  13. Dark Energy The influence of dark energy on the cosmic expansion leads to the integrated Sachs-Wolfe effect in the cosmic microwave background

  14. Dark Energy The influence of dark energy on the cosmic expansion modifies the distance to the CMB last scattering surface BOOMERANG, MAXIMA, TOCO

  15. Dark Energy Dark energy models with the same and all other parameters held fixed have nearly identical CMB anisotropy spectra. Huey et al, PRL 59 (1999) 063005

  16. Dark Energy evaluate classical tests of cosmology to constrain “w” Aldering et al, astro-ph/0507426

  17. Dark Energy evaluate classical tests of cosmology to constrain “w” Because dark energy kicks in at late times, find the greatest sensitivity at late times. Huterer & Turner, PRD 64 (2001) 123527

  18. Dark Energy forecasting SNAP: SuperNova Acceleration Probe snap.lbl.gov Kim et al, MNRAS 347 (2004) 909 recipe select theoretical model calculate F for proposed experiment use eigensystem to project limits Tegmark et al, astro-ph/9805117 Dodelson, “Modern Cosmology”, Ch 11

  19. Dark Energy Forecasting: H,q 2-D eigensystem:

  20. Dark Energy: Constant Equation-of-State Caldwell & Doran, PRD 69 (2004) 103517

  21. Dark Energy Test for super-acceleration phase Was w<-1 in the past? Fit a constant w to data (true w need not be constant) For fixed m , more negative w means more distant objects If w<-1 is found then w < -1, or m is wrong Kaplinghat & Bridle, PRD 71 (2005) 123003

  22. Dark Energy What are the fundamental bounds on w? Weak: Dominant: Timelike/Strong: Null: Hawking & Ellis, 1973

  23. Singuarities What is a singularity? A place where the curvature blows up! Excluded from the spacetime manifold… The Big Bang and Black Hole singularities are not part of the spacetime. Role of Energy Conditions: useful for identifying the forms of (realistic) matter which permit the proof of singularity theorems. New type of singularity: Sudden Future Singularity A spacelike singularity as the curvature diverges in finite time Barrow CQG 21 (2004) L79; PLB 180 (1987) 335 Davies, Ann. Inst. Henri Poincare 49 (1988) 297 Unnecessary to violate strong energy condition! Big Rip: violates null or dominant energy condition with w < -1 RC, Kamionkowski, Weinberg, PRL 91 (2003) 071301

  24. Dark Energy How to achieve w<-1? requires special considerations negative kinetic energy Hsu et al, PLB 597 (2004) 270 Cline et al, PRD 70 (2004) 043543 Carroll et al, PRD 68 (2003) 023509; PRD 71 (2005) 023525 Or it signals a breakdown of gravity? Dark matter? Or it simply means we are mis-interpreting the data!

  25. Phantom! Dark Energy: positive energy density increases with time! Universe ends catastrophically in a finite time! Caldwell, PLB 545 (2002) 23 Horizon radius shrinks to a point: every particle is torn away and isolated Force equation for a gravitationally-bound particle Caldwell et al, PRL 91 (2003) 071301 Perivolaropoulos, PRD 70 (2004) 123529 Objects on smaller and smaller scales will be ripped apart.

  26. Dr. Egon Spengler: There's something very important I forgot to tell you. Dr. Peter Venkman: What? Dr. Egon Spengler: Don't cross the streams. Dr. Peter Venkman: Why? Dr. Egon Spengler: It would be bad. Dr. Peter Venkman: I'm fuzzy on the whole good/bad thing. What do you mean "bad"? Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light. Dr. Raymond Stantz: Total protonic reversal. Dr. Peter Venkman: That's bad. Okay. Alright, important safety tip, thanks Egon. Ghostbusters (1984).

  27. Charting the CDM Spacetime Tamara Davis, astro-ph/0402278

  28. Conformal Diagrams: Mapping Infinity Hawking & Ellis, 1973 Chiba et al, CQG 22 (2005) 3745

  29. Looking Ahead… New ways to sense the dark energy Distances, Evolution, Cross-Correlation New ways to test gravity Cluster Lensing, 1/r in the laboratory New ideas from theory, clues from experiment Dark Energy Survey decam.fnal.gov Dark Matter Telescope www.dmtelescope.org SNAP snap.lbl.gov …

  30. Roadmap for Cosmology:New Physics in Light of Dark Energy Robert Caldwell Dartmouth College September 2005

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