Constraints on electromagnetic form factors of sub-GeV dark matter from the cosmic microwave background anisotropy

We consider dark matter which has nonzero electromagnetic form factors like electric/magnetic dipole moments and anapole moment for fermionic dark matter and Rayleigh form factor for scalar dark matter. We consider dark matter mass m(chi) > O(MeV) and put constraints on their mass and electromagnetic couplings from cosmic microwave background (CMB) and large scale structure (LSS) observations. Fermionic dark matter with nonzero electromagnetic form factors can annihilate to e(+)e(-) and scalar dark matter can annihilate to 2 gamma at the time of recombination and distort the CMB. We analyze dark matter with multipole moments with Planck and baryon acoustic oscillations (BAO) observations. We find upper bounds on anapole moment g(A) < 7.163 x 10(3) GeV-2, electric dipole moment D < 7.978 x 10(-9) e cm, magnetic dipole moment mu < 2.959 x 10(-7) mu(B), and the bound on Rayleigh form factor of dark matter is g(4)/Lambda(2)(4) < 1.085 x 10(-2) GeV-2 with 95% C.L.

Automated summary

The study focuses on dark matter with non-zero electromagnetic form factors, including fermionic and scalar dark matter. Constraints on mass and electromagnetic couplings are determined through observations of CMB and LSS. Analysis of dark matter with multipole moments yields upper bounds on various form factors.