Dipolar dark matter and CMB B-mode polarization

Abstract

We consider dark matter as singlet fermionic particles which carrying magnetic dipole moment to explore its contribution on the polarization of cosmic microwave background (CMB) photons. We show that Dirac fermionic dark matter has no contribution on the CMB polarization. However, in the case of Majorana dark matter this type of interaction leads to the B-mode polarization in presence of primordial scalar perturbations which is in contrast with standard scenario for the CMB polarization. We numerically calculate the B-mode power spectra and plot C BB l for different dark matter masses and the r-parameter. We show that the dark matter with masses less than 100MeV have valuable contribution on C BB l . Meanwhile, the dark matters with mass m d ≤ 50M eV for r = 0.07 ( m d ≤ 80M eV for r = 0.09) can be excluded experimentally. Furthermore, our results put a bound on the magnetic dipole moment about M ≤ 10 −16 e cm in agreement with the other reported constraints.

B-mode power spectrum of CMB via polarized Compton scattering

“…Also, any instrumental polarization rotation that can convert E-mode into B-mode and vice versa should be considered [58]. Some of our recent works also discussed the generation of B-mode polarization in the presence of scalar perturbations via Cosmic Neutrino Background and CMB interactions [46,59,60], nonlinear photons interactions [61], photon interaction by considering extensions to QED such as Lorentz-invariant violating operators [62], non-commutative geometry [48], interaction of dipolar dark matter with CMB photons [63], and photon-fermion forward scattering [64]. Moreover the intrinsic B-mode polarization is calculated using the Boltzmann code SONG [65] that is induced in the CMB by the evolution of primordial density perturbations at the second-order [66].…”

Impact of the vector dark matter on polarization of the CMB photon

“…For example, in [42] a fermionic DM has been considered as a dipolar DM which couples to photon through loops in the form of electric and magnetic dipole moments. Based on this model, the DM effects on the CMB photon polarization has been explored which is resulted in a B-mode polarization in presence of primordial scalar perturbations with a bound on the mass and magnetic dipole moment of dipolar DM about m ≥ 50M eV and M ≤ 10 −16 e cm, respectively [44].…”