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Swiss-Chees Cosmology & the Dark Energy Problem

Delve into the enigmatic realm of dark energy in the accelerating universe, pondering smallness and coincidence issues, homogeneity assumptions, and the impact of inhomogeneities. Investigate the role of first-order perturbation theory, examine the Swiss-Cheese model, and assess local and integrated effects on expansion history. Explore the potential explanations for cosmic anomalies and galaxy distribution discrepancies in this thought-provoking study.

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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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