http://arxiv.org/abs/1612.02104
We propose a new source of cosmic microwave background (CMB) $B$-mode polarization on sub-degree angular scales induced by dark matter density perturbation. If dark matter is ultra-light axion coupled to photon, its density fluctuations will induce cosmic birefringence fluctuations that would lead to a conversion of $E$-mode polarization of the CMB into B-mode polarization. We show that an allowed range of the coupling strength can produce $B$-mode polarization at sub-degree scales that can be observable in current and future CMB polarization experiments. These birefringence $B$ modes may manifest as an excess power at high $l$ in CMB lensing $B$-mode searches.
G. Liu and K. Ng
Thu, 8 Dec 16
51/69
Comments: submitted to Physics of the Dark Universe
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