Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2011-11-03
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
5 pages
Scientific paper
Primordial magnetic fields will generate non-Gaussian signals in the cosmic microwave background (CMB) as magnetic stresses and the temperature anisotropy they induce depend quadratically on the magnetic field. We compute a new measure of magnetic non-Gaussianity, the CMB trispectrum $T^{l_{_1}l_{_2}}_{l_{_3}l_{_4}}$, on large angular scales, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of $T^{l_{_1}l_{_2}}_{l_{_3}l_{_4}} \approx 5 \times 10^{-30}$ and $T^{l_{_1}l_{_2}}_{l_{_3}l_{_4}} \approx 10^{-19}$, respectively. Observational limits on CMB non-Gaussianity from WMAP7 data allow us to set sub-nanoGauss upper limits of $B_0 \lesssim 0.7 $ nG on the present value of the primordial cosmic magnetic field. This represents the tightest limit so far on the strength of primordial magnetic fields, on megaparsec scales, better than limits from the CMB bispectrum and all modes in the CMB power spectrum. Thus, the CMB trispectrum is a new and more sensitive probe of primordial magnetic fields on large scales.
Seshadri T. R.
Subramanian Kandaswamy
Trivedi Pranjal
No associations
LandOfFree
Cosmic Microwave Background Trispectrum and Primordial Magnetic Field Limits does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Cosmic Microwave Background Trispectrum and Primordial Magnetic Field Limits, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cosmic Microwave Background Trispectrum and Primordial Magnetic Field Limits will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-701467