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Title: CMB ISW-lensing bispectrum from cosmic strings

We study the effect of weak lensing by cosmic (super-)strings on the higher-order statistics of the cosmic microwave background (CMB). A cosmic string segment is expected to cause weak lensing as well as an integrated Sachs-Wolfe (ISW) effect, the so-called Gott-Kaiser-Stebbins (GKS) effect, to the CMB temperature fluctuation, which are thus naturally cross-correlated. We point out that, in the presence of such a correlation, yet another kind of the post-recombination CMB temperature bispectra, the ISW-lensing bispectra, will arise in the form of products of the auto- and cross-power spectra. We first present an analytic method to calculate the autocorrelation of the temperature fluctuations induced by the strings, and the cross-correlation between the temperature fluctuation and the lensing potential both due to the string network. In our formulation, the evolution of the string network is assumed to be characterized by the simple analytic model, the velocity-dependent one scale model, and the intercommutation probability is properly incorporated in order to characterize the possible superstringy nature. Furthermore, the obtained power spectra are dominated by the Poisson-distributed string segments, whose correlations are assumed to satisfy the simple relations. We then estimate the signal-to-noise ratios of the string-induced ISW-lensing bispectra and discuss the detectability ofmore » such CMB signals from the cosmic string network. It is found that in the case of the smaller string tension, Gμ << 10{sup -7}, the ISW-lensing bispectrum induced by a cosmic string network can constrain the string-model parameters even more tightly than the purely GKS-induced bispectrum in the ongoing and future CMB observations on small scales.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Research Center for the Early Universe, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  2. Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561 (Japan)
  3. Faculty of Science, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)
Publication Date:
OSTI Identifier:
22370684
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 02; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CORRELATIONS; EVOLUTION; FLUCTUATIONS; POTENTIALS; PROBABILITY; RELICT RADIATION; SCALE MODELS; SIGNALS; SIGNAL-TO-NOISE RATIO; SPECTRA; STATISTICS; STRING MODELS; VELOCITY