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Input for fundamental physics Model independent way to extract information

Ram Brustein. אוניברסיטת בן-גוריון. Determining the nature of DARK ENERGY. Irit Maor Paul Steinhardt. Input for fundamental physics Model independent way to extract information Known tests (very) sensitive to theoretical priors  challenges to experiment & theory.

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Input for fundamental physics Model independent way to extract information

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  1. Ram Brustein אוניברסיטת בן-גוריון Determining the nature of DARK ENERGY Irit Maor Paul Steinhardt • Input for fundamental physics • Model independent way to extract information • Known tests (very) sensitive to theoretical priors  challenges to experiment & theory

  2. additional possibilities: r - Tegmark state finder:Sahni et al. FP model EOS Focus on: Equation Of State • Space curvature w = -1/3 • Higher tensor invariants • Scalar fields • Extra dimensions • Scale dependent GN • Modified Friedman eq. • and more, … • “never underestimate the creativity of a theorist!” standard GR form

  3. Classic tests measure integrals of EOS background • luminosity distance • volume • angular distance • shear fluctuations • ISW • linear/non-linear growth factors • speed of sound situation clear • D situation unclear: Please help!

  4. For example:Luminosity distancedLvs. redshiftz Textbook form is not sufficient

  5. Splitting components off, for example, NR matter (dark and visible) g= Wm /(1- Wm)

  6. Degeneracy! Maor et al. (2001) • DL • D DL/DL • wQ (z) • For 9 differentEOS • Assuming • 1. perfect knowledge of WM • 2. flat U.

  7. N O T MEASURE w' I. Maor et al J. Frieman et al P. Antilogus Weller & Albrecht Similar conclusions P. Astier, Kujat et al, E. Linder, ...

  8. Fast roll – wf ~ +1 Slow roll – wf ~ -1 Oscillations – wf~ 0 wf < -1, wf> +1 possible, easy !!! High sensitivity to choice of theoretical framework and priors • need to keep an open mind about priors: for example restricting wQ>-1 • present experimental results in a way that will allow modifying priors • use some input from theory to parametrize evolution Practical implications:

  9. Breaking the Degeneracy ? I.Combine different types of high precision (~ percent) measurements  about 20% in current value of wQ & not very helpful for time-dependence, but … • sensitivity estimates depend on actual value of EOS: away from -1 / large positive w' are best • Hard to distinguish between different forms of DE. * * partial analysis

  10. For example: CMB + SNIa Maor et al (2002) Maor & Brustein (2003) Frieman et al, Caldwell & Doran, ... • DE expected to “disappear” for z > 2 • CMB photons travel most of the way through MD U.  No gain compared to “low z” probes • Best accuracy for dA from CMB ~ 1% (e.g. 1st peak)  CMB comparable to future SNIa experiments (WM known+ flat U.+…) • Confusion about possible attainable sensitivity of other experiments (shear, volume, growth factor, …)

  11. Breaking the Degeneracy ? II.Invent new “local” tests: “move the detector to a different z” III.Accept theoretical input: e.g.: that dark energy is a CC, a specific quintessence model, …

  12. Jimenez & Loeb, Jimenez et al Measure z(t) Practical ??

  13. Conclusions Known tests (very) sensitive to theoretical priors  Challenges to Experiment & Theory • Need: public access to data  independent combined analysis  explore different priors • Need: • either a new “local” test - ??? • or new theoretical input - ??? • orLUCK 

  14. Maor & Brustein (2003) • CMB vs. SN Ia x=z+1

  15. Linder, astro-ph/0212... Maor et al astro-ph/0112...

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