Cosmic Birefringence from Monodromic Axion Dark Energy

Abstract

The recently reported non-zero isotropic birefringence angle in Planck 2018 polarization data provides a tantalizing hint for new physics of axions. In this paper, we explain this by a string theory motivated axion with a monodromy potential that plays the role of dark energy. Upon using the birefringence measurement and the constraint on the equation of state for dark energy in this scenario, we find an upper bound on the axion decay constant as f a 10 16 GeV. This naturally gives an energy scale of order GUT and can resolve the theoretical issue of super-Planckian field range of the conventional axion dark energy model. We further study the implications of cosmic birefringence for the underlying theory and its consequences for the string swampland conjectures. We finally discuss oscillatory features in the dark energy sector and the expected cosmic birefringence tomography.

Improved Constraints on Cosmic Birefringence from the WMAP and Planck Cosmic Microwave Background Polarization Data

“…To this end, both on-going and future groundbased [58][59][60][61][62][63][64][65][66], balloon-borne [67,68], and spaceborne [69,70] experiments are expected to lead to a convincing discovery (or otherwise) of cosmic birefringence. If proven to be a cosmological signal, isotropic cosmic birefringence would have a profound impact on cosmology, particle physics, and quantum gravity [71][72][73][74][75][76][77][78][79][80][81].…”

Probing cosmic birefringence with polarized Sunyaev-Zel’dovich tomography

“…where we set V (φ) = m 2 φ φ 2 /2 and the prime denotes the derivative with respect to the conformal time. Note that, however, our method can be applied to any kinds of potential in general including recent works studying axion-like dark energy [55][56][57][58]. Similar to Ref.…”

Impact of Anisotropic Birefringence on Measuring Cosmic Microwave Background Lensing

“…Cosmic birefringence therefore has gained growing interest; for a recent review see, e.g., [22]). Anticipating such a discovery, multiple recent papers have explored the potential of future CMB experiments to constrain the mass of axion-like particles [23][24][25][26] and to probe models which produce both isotropic and anisotropic cosmic birefringence [27][28][29][30].…”