Impact of the vector dark matter on polarization of the CMB photon
We consider a vector dark matter (VDM) with a direct coupling with photon. We examine the effect of such an interaction on the CMB polarization to put new constrains on the properties of the DM particles. We show that a partially polarized VDM of the order of temperature fluctuation with a quadrupole distribution leads to a valuable CP for the CMB. In different DM-models the DM-masses range from few $eV$ to a few $TeV$. We show that the CP angular power spectrum depends on the mass of VDM as $C^{(S)}_{Vl}\propto 1/m_{_{V}}^6$ such that for $m_{_{V}}=10eV-1keV$, the CP angular power spectrum is $C^{(S)}_{Vl}\simeq 10^3- 10^{-11}{\rm nK^2}$. Therefore, the light VDM with masses less than $10 eV$ leads to an unexpected very large CP which can be excluded from the acceptable range of the VDM masses.