Parity violation of primordial magnetic fields in the CMB bispectrum

Journal Article · Fri Jun 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/06/015· OSTI ID:22279801

Shiraishi, Maresuke ^[1]

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1. Department of Physics and Astrophysics, Nagoya University, Nagoya 464-8602 (Japan)

We study the parity violation in the cosmic microwave background (CMB) bispectrum induced by primordial magnetic fields (PMFs). Deriving a general formula for the CMB bispectrum generated from not only non-helical but also helical PMFs, we find that helical PMFs produce characteristic signals, which disappear in parity-conserving cases, such as the intensity-intensity-intensity bispectra arising from Σ{sup 3}{sub n=1}l{sub n} = odd. For fast numerical calculation of the CMB bispectrum, we reduce the one-loop formula to the tree-level one by using the so-called pole approximation. Then, we show that the magnetic anisotropic stress, which depends quadratically on non-helical and helical PMFs and acts as a source of the CMB fluctuation, produces the local-type non-Gaussianity. Comparing the CMB bispectra composed of the scalar and tensor modes with the noise spectra, we find that assuming the generation of the nearly scale-invariant non-helical and helical PMFs from the grand unification energy scale (10{sup 14}GeV) to the electroweak one (10{sup 3}GeV), the intensity-intensity-intensity bispectrum for Σ{sup 3}{sub n=1}l{sub n} = odd can be observed by the WMAP experiment under the condition that B{sub 1Mpc;}{sup 2/3}B{sub 1Mpc;}{sup 1/3} > 2.7−4.5nG with B{sub 1Mpc;} and B{sub 1Mpc;} being the non-helical and helical PMF strengths smoothed on 1 Mpc, respectively.

• OSTI ID: 22279801
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 06 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
APPROXIMATIONS
COMPARATIVE EVALUATIONS
COSMOLOGICAL MODELS
COSMOLOGY
FLUCTUATIONS
GRAND UNIFIED THEORY
MAGNETIC FIELDS
NOISE
P INVARIANCE
PARITY
RELICT RADIATION
SCALARS
SCALE INVARIANCE
STRESSES
TENSORS