The CMB temperature bispectrum induced by cosmic strings

Understand

The Cosmic Microwave Background (CMB) bispectrum of the temperature anisotropies induced by a network of cosmic strings is derived for small angular scales, under the assumption that the principal cause of temperature fluctuations is the Gott-Kaiser-Stebbins (GKS) effect.

• We provide analytical expressions for all isosceles triangle configurations in Fourier space.
• Their overall amplitude is amplified as the inverse cube of the angle and diverges for flat triangles.
• The isosceles configurations generically lead to a negative bispectrum with a power law decay l^(-6) for large multipole l.