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2nd KIAS Workshop on Cosmology and Structure Formation KIAS, Seoul, Korea Sep 20-21, 2006

Non-Gaussianity from Quantum Fluctuations during Inflation Kin-Wang Ng Institute of Physics & Institute of Astronomy and Astrophysics Academia Sinica, Taiwan, ROC. 2nd KIAS Workshop on Cosmology and Structure Formation KIAS, Seoul, Korea Sep 20-21, 2006.

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2nd KIAS Workshop on Cosmology and Structure Formation KIAS, Seoul, Korea Sep 20-21, 2006

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  1. Non-Gaussianity from Quantum Fluctuations during InflationKin-Wang Ng Institute of Physics & Institute of Astronomy and AstrophysicsAcademia Sinica, Taiwan, ROC 2nd KIAS Workshop on Cosmology and Structure Formation KIAS, Seoul, Korea Sep 20-21, 2006 CH Wu, KW Ng, WL Lee, DS Lee, YY Charng, astro-ph/0604292

  2. Introduction • WMAP 3-year data and other CMB expts Challenges to standard slow-roll inflation?! low CMB quadrupole , running spectral index, nongaussianity, south-north asymmetry, axis of evil (in Park’s talk),.. • Inflaton coupled to other quantum fields natural, reheating,.. still single-field inflation(see multi-field inflation in Steward’s talk) • Quantum environment behaves like colored quantum noise – kicks inflaton (Brownian motion) • Noise-induced (passive) inflaton fluctuations in addition to active de Sitter quantum fluctuations

  3. WMAP 3-year TT, TE, EE, CMB power spectra low quadrupole

  4. Cosmological Parameters ns=0.961 @ k=0.05Mpc-1

  5. WMAP3 Data on Running Spectral Idex r : tenor/scalar ns :scalar spectral index dns/dlnk: running index ns 0.05= 0.961 k=0.002Mpc-1

  6. PR(k)= (δρ/ρ)2 |dn/dlnk| << |n-1|

  7. WMAP3 and inflation models These models predict that

  8. Curvature potential Slow-roll inflation Radiation transfer function ▽2Φ=δρ/ρ WMAP3 Data on Non-Gaussianity

  9. Slow-roll kinematics Quantum fluctuations A Challenge to Standard Slow-roll inflation!? • Chaotic inflation – classical fluctuations driven by a white noise (Starobinsky) or by a colored noise (Liguori, Matarrese et al.) coming from high-k inflaton • Driven by a colored noise from interacting quantum environment (Wu et al) • Others • Slow-roll conditions violated after horizon crossing (Leach et al) • General slow-roll condition (Steward) |n-1|~|dn/dlnk| • Multi-field (Vernizzi, Tent, Rigopoulos, Yokoyama et al) • etc

  10. Our Inflaton-Scalar Interacting Model Single-field inflation〈σ〉= 0

  11. Dissipation Noise Trace out sigma field to obtain : Colored, dependent on history

  12. Start of inflation

  13. Dominant passive fluctuations and low CMB quadrupole assuming no active de Sitter quantum fluctuations

  14. Scale-invariant de Sitter inflaton quantum fluctuations Low CMB quadrupole and onset of inflation at large k

  15. Relative large three-point functions ns Dissipation? Conclusions • Hints from WMAP3 data on beyond standard slow-roll inflation • We propose a new dynamical source for density perturbation: Colored Quantum Noise - give alow CMB quadrupole - probing the first few efoldings of inflation !? • Working on running spectral index and non-Gaussianity, both are natural with colored noise

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