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Swiss-Chees Cosmology & the Dark Energy Problem

Swiss-Chees Cosmology & the Dark Energy Problem. Tirthabir Biswas Penn-State University, University Park With Alessio Notari and Reza Mansouri, astro-ph/0606703 With Alessio Notari, astro-ph/0702555 More to come. The Dark Energy Problem. The Universe seem to be accelerating today

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Swiss-Chees Cosmology & the Dark Energy Problem

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  1. Swiss-Chees Cosmology & the Dark Energy Problem Tirthabir Biswas Penn-State University, University Park With Alessio Notari and Reza Mansouri, astro-ph/0606703 With Alessio Notari, astro-ph/0702555 More to come

  2. The Dark Energy Problem The Universe seem to be accelerating today Why is this such a big puzzle? • Smallness Problem • Coincidence or Why now Problem

  3. The Inhomogeneous Universe Is homogeneity a good assumption? What do we really measure? • Redshift • Luminocity Distance Equivalently, Evolution history of universe effects DL(z) , but Inhomogeneities also effect light paths, or DL(z)

  4. Why and why not ? • First Order perturbation theory yields No “average” corrections: Local corrections, Non-linear effects • Φ is small: At At How are corrections related to Φ ? • Cancellation between voids and structures: More of voids

  5. Swiss-Cheese toy Model Spherically symmetric LTB metric Characterized by a single `curvature function’ k(r)

  6. How can it work? • Scenario I, Average or integrated effect: Light passes through hundreds of patches ~ 30 Mpc and pick up net correction Doesn’t work • Scenario II, Local Effect: We are sitting inside a large ~ 300 Mpc void! z<0.1, nearby supernova’s inside the patch, experience a faster local Hubble expansion z>0.1 outside the patch, see average expansion

  7. Assessment • Supernova works • Host of other measurements: CMB (fits 1st peak), baryon oscillation (fits the data), local density measurements (preliminary check) Needs more comprehensive analysis. • How likely is our void and our central position? • Large Angle anomalies in CMB can be explained![Silk, Inoue] • Reports 25% less galaxy around a 300 Mpc region [Frith et al]

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