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CMB temperature b ispectrum from a cosmic string network

CMB temperature b ispectrum from a cosmic string network. Keitaro Takahashi (Kumamoto U). Based on the collaboration with. Yamauchi (U Tokyo), Sendouda ( Hirosaki U), Yoo (Nagoya), Hiramatsu (Kyoto). Cosmic strings Cosmic superstrings. L ine-like topological defects

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CMB temperature b ispectrum from a cosmic string network

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  1. CMB temperature bispectrum from a cosmic string network Keitaro Takahashi (Kumamoto U) Based on the collaboration with Yamauchi (U Tokyo), Sendouda (Hirosaki U), Yoo (Nagoya), Hiramatsu (Kyoto)

  2. Cosmic strings Cosmic superstrings • Line-like topological defects • Formed in the early universe • through the spontaneous • symmetry breaking • F-strings, D-strings, and their bound states which appear in string theory • Formed though the brane collision at the end of the stringy inflation • Intercommuting probabilityP P=1 P~10-3<<1

  3. String gravity : conical structure The spacetime around a straight cosmic string is locally flat. An angular wedge of width Δ=8πGμ is removed from the space and the remaining edges identified.

  4. String-induced integrated Sachs-Wolfe effect Cosmic strings create line-like discontinuities in the CMB signal. Gott-Kaiser-Stebbins (GKS) effect [Kaiser+Stebbins(1984), Gott III(1985)] [Planck 25 (2013)] (δT/T)/Gμ

  5. CMB temp. power spectrum induced by a cosmic string network [Atacama Cosmology Telescope (ACT), 2010] For ACT, For Planck satellite, An analytic model including the probabilistic nature of the intercomuting process [Yamauchi, KT, et al. (2011)]

  6. CMB lensing UnlensedCMB map • Deflection of CMB photons z=zCMB potential z=zL geodesic Lensed CMB map z=0 Lensing contribution [Hu+Okamoto(2002)]

  7. “αβ-type” lensing bispectrum • The anisotropy is assumed to be decomposed into (α,β : contributions from each components) • “αβ-type” lensing bispectrum

  8. Various types of CMB lensing : contributions from cosmic strings “P” : primordial density perturbations, “S” : string contributions • PP-type (standard) • PS-type Standard density pert. Standard density pert. Cosmic strings Standard density pert. • SP-type • SS-type Standard density pert. Cosmic strings Cosmic strings Cosmic strings

  9. Equilateral-shaped bispectrainduced by a cosmic string network SS-type ∝ ClΘsφsClΘsΘs ∝(Gμ)4 SP-type ∝ ClΘsφsClΘpΘp ∝(Gμ)2 (GKS)3 ∝(Gμ)3 Preliminary PS-type ∝ ClΘpφpClΘsΘs ∝ (Gμ)2 (Gμ,P) Silk damping (10-7,1) (10-8,10-3) (10-9,10-6) • At small scale, the standard ISW-L (PP-type) and SP-type bispectra are damped due to the Silk damping, and only the (GKS)3, PS-type bispectra are relevant. [Yamauchi, KT, et al., in prep.]

  10. [Yamauchi, KT, et al., in prep.] Cumulative signal-to-noise ratio SS-type ∝(Gμ)4 (GKS)3 ∝(Gμ)3 SP-type ∝(Gμ)2 PS-type ∝ (Gμ)2 Preliminary PA : Planck+ACTPol–like noise, P : Planck-like noise

  11. [Yamauchi, KT, et al., in prep.] Constraint in Gμ-P plane ((S/N)<5000=1) SP-type ∝ ClΘsφsClΘpΘp Preliminary (GKS)3 SS-type ∝ ClΘsφsClΘsΘs PS-type ∝ ClΘpφpClΘsΘs For small P, the PS-type GKS-L bispectrum∝ ClΘpφpClΘsΘs∝ (Gμ)2gives the tighter constraint on Gμ than the (GKS)3bispectrum∝ (Gμ)3.

  12. Summary • We study the effect of weak lensing by cosmic strings on the anisotropies of cosmic microwave background. • In developing a method to evaluate the lensing contribution due to strings, we calculate the analytic expression for the various-type, namely αβ-type, lensing bispectra. • For smaller tension, the lensing bispectrum have window to constrain the string parameters even tighter than the bispectrum induced by GKS.

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