Searching for a cosmological preferred direction with 147 rotationally supported galaxies

Abstract

It is well known that the Milgrom's MOND (modified Newtonian dynamics) explains well the mass discrepancy problem in galaxy rotation curves. The MOND predicts a universal acceleration scale below which the Newtonian dynamics is invalid yet. The universal acceleration scale we got from the SPARC dataset is $g_{†}=1.02\times 10^{-10}\mathrm{m}{\mathrm{s}}^{-2}$. Milgrom suggested that the acceleration scale may be a fingerprint of cosmology on local dynamics and related with the Hubble constant $g_{†}\sim c{H}_0$. In this paper, we use the hemisphere comparison method with the SPARC dataset to investigate the spatial anisotropy on the acceleration scale. We find that the hemisphere of the maximum acceleration scale is in the direction $(l,b)=({175.5^{\circ }}_{-10^{\circ }}^{+6^{\circ }},{-6.5^{\circ }}_{-3^{\circ }}^{+8^{\circ }})$ with $g_{†,max}=1.10\times 10^{-10}\mathrm{m}{\mathrm{s}}^{-2}$, while the hemisphere of the minimum acceleration scale is in the opposite direction $(l,b)=({355.5^{\circ }}_{-10^{\circ }}^{+6^{\circ }},{6.5^{\circ }}_{-8^{\circ }}^{+3^{\circ }})$ with $g_{†,min}=0.76\times 10^{-10}\mathrm{m}{\mathrm{s}}^{-2}$. The maximum anisotropy level reaches up to $0.37\pm 0.04$. Robust tests present that such a level of anisotropy can't be reproduced by a statistically isotropic data. In addition, we show that the spatial anisotropy on the acceleration scale has little correlation with the non-uniform distribution of the SPARC data points in sky. We also find that the maximum anisotropy direction is close with other cosmological preferred directions, especially the direction of the "Australia dipole" for the fine structure constant.

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Cited by in corpus (4)

• Anisotropy of the Universe via the Pantheon supernovae sample revisited
• Constraining the anisotropy of the Universe via Pantheon supernovae sample
• Testing cosmic anisotropy with Pade approximation and Pantheon+ sample
• On the absence of a universal surface density, and a maximum Newtonian acceleration in dark matter haloes: consequences for MOND