Updated constraints on spatial variations of the fine-structure constant

Abstract

Recent work by Webb et al. has provided indications of spatial variations of the fine-structure constant, α, at a level of a few parts per million. Using a dataset of 293 archival measurements, they further show that a dipole provides a statistically good fit to the data, a result subsequently confirmed by other authors. Here we show that a more recent dataset of dedicated measurements further constrains these variations: although there are only 10 such measurements, their uncertainties are considerably smaller. We find that a dipolar variation is still a good fit to the combined dataset, but the amplitude of such a dipole must be somewhat smaller: 8.1 ± 1.7 ppm for the full dataset, versus 9.4 ± 2.2 ppm for the Webb et al. data alone, both at the 68.3% confidence level. Constraints on the direction on the sky of such a dipole are also significantly improved. On the other hand the data can't yet discriminate between a pure spatial dipole and one with an additional redshift dependence.

Constraining spatial variations of the fine structure constant using clusters of galaxies and Planck data

“…Other analyses have confirmed these results [3,4], although the inclusion of more recent measurements reduces the allowed amplitude by about twenty percent [5], to a maximum of about 8 parts per million (with no significant changes to the preferred direction). Although it is clear that some systematic effects are present in the archival data [6], it is presently unclear if they could explain the above results [7,8].…”

Testing the anisotropy of the universe using the simulated gravitational wave events from advanced LIGO and Virgo

“…Convert d L and σ d L to μ and σ μ using Eqs. (14) and (15). Calculate the anisotropic distance modulus μ using Eq.…”

“…However, a e-mail: linhn@ihep.ac.cn b e-mail: cqujinli1983@cqu.edu.cn c e-mail: lixin1981@cqu.edu.cn some other observations show that the universe may deviate from the statistical anisotropy. These include but not limited to the large scale bulk flow [8,9], the CMB temperature anisotropy [10,11], the spatial variation of the electromagnetic fine-structure constant [12][13][14][15], the anisotropy of the distance-redshift relation of type-Ia supernovae [16][17][18]. If the universe is indeed anisotropic, it implies that there are new physics beyond the standard model.…”

Spatial and temporal variations of the fine-structure constant in the Finslerian universe

“…[8], and the rest 10 measurements are taken from various literatures and are compiled in Ref. [9]. We find the dipole direction pointing Ω m0 = 0.278, which are derived by fitting to the Union2.1 data set [34] using the standard ΛCDM model.…”

“…22 −0.20 ) × 10 −5 [7]. Recently, Pinho & Martins [9] carried out a joint analysis of a larger number of old α e data [8] and ten more recent measurements of α e [10][11][12][13][14][15][16][17], and found that the dipolar variation of α e with amplitude (0.81±0.17)×10 −5 is still a good fit to the combined data set, while the statistical uncertainty is significantly reduced compared with previous results.…”