CMB
BBN




CMB

I. Primordial magnetic fields and CMB

Primordial magnetic fields (PMFs), which were generated in the early universe before recombination, affect the motion of plasma and then the cosmic microwave background (CMB) and the matter power spectrum (MPS). We consider constraints on PMFs with a characteristic correlation length from the observations of the anisotropies of CMB (WMAP, QUAD, ACT, SPT, and ACBAR) and MPS. The spectrum of PMFs is modeled with multilognormal distributions (MLND), rather than powerlaw distribution, and we derive constraints on the strength B ( k ) at each wavenumber k along with the standard cosmological parameters in the flat Universe and the foreground sources. We obtain upper bounds on the field strengths at
k = 10^{1, 2, 4. 5} Mpc^{1} as 4.7 nG, 2.1 nG, 5.3 nG and 10.9 nG (2σ C.L.) respectively, while the field strength at k = 10^{3} Mpc^{1} turns out to have a finite value as
B ( k =10^{3} Mpc^{1} ) = 6.2 ± 1.3 nG (1σ C.L.).
This finite value is attributed to the finite values of BB mode data at l > 300 obtained from QUAD experiment. If we do not include the BB mode data, we obtain only the upper bound on B ( k =10^{3} Mpc^{1} ).
Please visit here (details in Japanese) for more detail.
[arXiv:1311.2584]

Fig. 1;
Probability distributions of the PMF strengths at k = 10^{3} Mpc^{1} from the CMB and the MPS data with the BB mode (solid) and without (dotted).






