Spatial variations of the fine-structure constant in symmetron models

M. F. Silva, H. A. Winther, D. F. Mota, C. J. A. P. Martins

Abstract
We investigate the variation of the fine-structure constant, α, in symmetron models using N-body simulations in which the full spatial distribution of α at different redshifts has been calculated. In particular, we obtain simulated sky maps for this variation, and determine its power spectrum. We find that in high-density regions of space (such as deep inside dark matter halos) the value of α approaches the value measured on Earth. In the low-density outskirts of halos the scalar field value can approach the symmetry breaking value and leads to significantly different values of α. If the scalar-photon coupling strength ß_γ is of order unity we find that the variation of α inside dark matter halos can be of the same magnitude as the recent claims by Webb et al. of a dipole variation. Importantly, our results also show that with low-redshift symmetry breaking these models exhibit some dependence of α on lookback time (as opposed to a pure spatial dipole) which could in principle be detected by sufficiently accurate spectroscopic measure ments, such as those of ALMA and the ELT-HIRES.

Physical Review D
Volume 89, Page 024025_1
January 2014

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