The scalar, vector and tensor contributions of a stochastic background of magnetic fields to cosmic microwave background anisotropies |
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| Authors: | D Paoletti F Finelli F Paci |
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| Institution: | Dipartimento di Fisica, Universitàdegli studi di Ferrara and INFN, via Saragat 1, I-44100 Ferrara, Italy;INAF–IASF Bologna, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Istituto Nazionale di Astrofisica, via Gobetti 101, I-40129 Bologna, Italy;INAF–OAB, Osservatorio Astronomico di Bologna, Istituto Nazionale di Astrofisica, via Ranzani 1, I-40127 Bologna, Italy;INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna, Italy;Dipartimento di Astronomia, Universitàdegli Studi di Bologna, via Ranzani 1, I-40127 Bologna, Italy |
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| Abstract: | We study the contribution of a stochastic background (SB) of primordial magnetic fields (PMFs) on the anisotropies in temperature and polarization of the cosmic microwave background (CMB) radiation. A SB of PMF modelled as a fully inhomogeneous component induces non-Gaussian scalar, vector and tensor metric linear perturbations. We give the exact expressions for the Fourier spectra of the relevant energy–momentum components of such a SB, given a power-law dependence parametrized by a spectral index nB for the magnetic field power spectrum cut at a damping scale k D. For all the values of nB considered here, the contribution to the CMB temperature pattern by such a SB is dominated by the scalar contribution and then by the vector one at higher multipoles. We also give an analytic estimate of the scalar contribution to the CMB temperature pattern. |
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| Keywords: | magnetic fields cosmic microwave background |
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