Cosmic string power spectrum, bispectrum, and trispectrum

Regan, D M; Shellard, E P. S.

doi:10.1103/PHYSREVD.82.063527

Title: Cosmic string power spectrum, bispectrum, and trispectrum

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Abstract

We use analytic calculations of the post-recombination gravitational effects of cosmic strings to estimate the resulting CMB power spectrum, bispectrum and trispectrum. We place a particular emphasis on multipole regimes relevant for forthcoming CMB experiments, notably the Planck satellite. These calculations use a flat-sky approximation, generalizing previous work by integrating string contributions from last scattering to the present day, finding the dominant contributions to the correlators for multipoles l>50. We find a well-behaved shape for the string bispectrum (without divergences) which is easily distinguishable from the inflationary bispectra which possess significant acoustic peaks. We estimate that the nonlinearity parameter characterizing the bispectrum is approximately 0 > or approx. f{sub NL} > or approx. -40 (given present string constraints from the CMB power spectrum). We also apply these unequal time correlator methods to calculate the trispectrum for parrallelogram configurations, again valid over a large range of angular scales relevant for WMAP and Planck, as well as on very small angular scales. We find that, unlike the bispectrum which is suppressed by symmetry considerations, the trispectrum for cosmic strings is large. Our current estimate for the trispectrum parameter is {tau}{sub NL{approx}}10{sup 5}, which may provide one of the strongest constraints on themore » string model in future analysis.« less

Authors:

Regan, D M; Shellard, E P. S. ^[1]

Centre for Theoretical Cosmology, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

Publication Date:: Wed Sep 15 00:00:00 EDT 2010

OSTI Identifier:: 21421134

Resource Type:: Journal Article

Journal Name:: Physical Review. D, Particles Fields

Additional Journal Information:: Journal Volume: 82; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevD.82.063527; (c) 2010 American Institute of Physics; Journal ID: ISSN 0556-2821

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COSMIC RADIATION; GRAVITATION; MULTIPOLES; NONLINEAR PROBLEMS; PEAKS; RECOMBINATION; RELICT RADIATION; SCATTERING; SIMULATION; SPECTRA; STRING MODELS; SYMMETRY; CALCULATION METHODS; COMPOSITE MODELS; ELECTROMAGNETIC RADIATION; EXTENDED PARTICLE MODEL; IONIZING RADIATIONS; MATHEMATICAL MODELS; MICROWAVE RADIATION; PARTICLE MODELS; QUARK MODEL; RADIATIONS

Citation Formats


                    Regan, D M, and Shellard, E P. S. Cosmic string power spectrum, bispectrum, and trispectrum.  United States: N. p., 2010. 
        Web.  doi:10.1103/PHYSREVD.82.063527.

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                    Regan, D M, & Shellard, E P. S. Cosmic string power spectrum, bispectrum, and trispectrum.  United States.  https://doi.org/10.1103/PHYSREVD.82.063527

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                    Regan, D M, and Shellard, E P. S. 2010.  
        "Cosmic string power spectrum, bispectrum, and trispectrum".  United States.  https://doi.org/10.1103/PHYSREVD.82.063527.

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@article{osti_21421134,

  title        = {Cosmic string power spectrum, bispectrum, and trispectrum},

  author       = {Regan, D M and Shellard, E P. S.},

  abstractNote = {We use analytic calculations of the post-recombination gravitational effects of cosmic strings to estimate the resulting CMB power spectrum, bispectrum and trispectrum. We place a particular emphasis on multipole regimes relevant for forthcoming CMB experiments, notably the Planck satellite. These calculations use a flat-sky approximation, generalizing previous work by integrating string contributions from last scattering to the present day, finding the dominant contributions to the correlators for multipoles l>50. We find a well-behaved shape for the string bispectrum (without divergences) which is easily distinguishable from the inflationary bispectra which possess significant acoustic peaks. We estimate that the nonlinearity parameter characterizing the bispectrum is approximately 0 > or approx. f{sub NL} > or approx. -40 (given present string constraints from the CMB power spectrum). We also apply these unequal time correlator methods to calculate the trispectrum for parrallelogram configurations, again valid over a large range of angular scales relevant for WMAP and Planck, as well as on very small angular scales. We find that, unlike the bispectrum which is suppressed by symmetry considerations, the trispectrum for cosmic strings is large. Our current estimate for the trispectrum parameter is {tau}{sub NL{approx}}10{sup 5}, which may provide one of the strongest constraints on the string model in future analysis.},

  doi          = {10.1103/PHYSREVD.82.063527},

  url          = {https://www.osti.gov/biblio/21421134},
  journal      = {Physical Review. D, Particles Fields},

  issn         = {0556-2821},

  number       = 6,

  volume       = 82,

  place        = {United States},

  year         = {Wed Sep 15 00:00:00 EDT 2010},

  month        = {Wed Sep 15 00:00:00 EDT 2010}

}

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