Effects of spacetime anisotropy on the galaxy rotation curves

Abstract

The observations on galaxy rotation curves show significant discrepancies from the Newtonian theory. This issue could be explained by the effect of the anisotropy of the spacetime. Conversely, the spacetime anisotropy could also be constrained by the galaxy rotation curves. Finsler geometry is a kind of intrinsically anisotropic geometry. In this paper, we study the effect of the spacetime anisotropy at galactic scales in the Finsler spacetime. It is found that the Finslerian model has close relations with the Milgrom's MOND. By performing the best-fit procedure to the galaxy rotation curves, we find that the anisotropic effects of the spacetime become significant when the Newtonian acceleration GM/r 2 is smaller than the critical acceleration a 0 . Interestingly, the critical acceleration a 0 , although varies between different galaxies, is in the order of magnitude cH 0 /2π ∼ 10 −10 m s −2 .

Constraining anisotropy of the universe from different groups of type-Ia supernovae

“…The luminosity distance depends on not only the redshift, but also the direction. A direct fit to the Union2 dataset shows that the magnitude of anisotropy is about D ≈ 0.03 ± 0.03, and the privileged axis points towards [35]. This axis is close to the direction of highest expansion of the universe found by Kalus et al [25].…”

“…We note that the Finsler-Randers spacetime [32][33][34][35] provides an appropriate framework for the anisotropic cosmology. The line element in Finsler-Randers spacetime can be described by the FRW line element with an extra 1-form [35]. This 1-form picks out a privileged axis so that the universe becomes axissymmetric.…”

Cosmic magnetization in curved and Lorentz violating space–times

“…All this phenomenology and cosmological constraints combined with particular QG theories where the effective geometry is Finslerian can give a better insight about LV and the colorful morphology of the physical manifold. This detailed and complicated analysis is an intriguing open challenge (for some recent studies see [91][92][93][94][95][96][153][154][155][156][157][158][159][160]). Since our amplification mechanism strongly depends on the intensity of Cartan tensor and its evolution in time, constraining the 'Finslerity' of space-time may lead to a better understanding of why our universe is magnetized.…”

Comparison between hemisphere comparison method and dipole-fitting method in tracing the anisotropic expansion of the Universe use the Union2 data set

“…Generally speaking, there are two different ways to investigate the possible anisotropy from the data. One is directly fitting the data to a specific anisotropic cosmological model (Campanelli et al 2011;Li et al 2013;Chang et al 2013Chang et al , 2014aSchücker et al 2014). Many anisotropic cosmological models have be proposed to match the observations.…”