Zhe Chang, Ming-Hua Li, Xin Li, Sai Wang
The data of the Bullet Cluster 1E0657-558 released on November 15, 2006
reveal that the strong and weak gravitational lensing convergence $\kappa$-map
has an $8\sigma$ offset from the $\Sigma$-map. The observed $\Sigma$-map is a
direct measurement of the surface mass density of the ICM gas. It accounts for
83% of the averaged mass-fraction of the system. This suggests a modified
gravity theory at large distances different from Newton's inverse-square
gravitational law. In this paper, as a cluster scale generalization of
Grumiller's modified gravity model, we present a gravity model with a
generalized linear Rindler potential in Randers-Finslerian spacetime. The
galactic limit of the model is qualitatively consistent with the MOND and the
Grumiller's. It yields approximately the flatness of the rotational velocity
profile at the radial distance of several kpcs and gives the velocity scales
for spiral galaxies at which the curves become flattened. These results are
observation-compatible. Plots of convergence $\kappa$ for a galaxy cluster show
that the peak of the gravitational potential has chances to lie on the
outskirts of the baryonic mass center. For proper parameter values, we obtain a
reasonable isothermal temperature of the main cluster and simultaneously
ameliorated the shape of the convergence $\kappa$ curve. The temperature given
by the model is $T\simeq 13.1$ keV, slightly lower than the observational value
$T=14.8_{-1.2}^{+1.7}$ keV.
View original:
http://arxiv.org/abs/1110.3893
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