Abstract:
The presence of dark matter (DM), though well established by indirect evidence, is yet
to be observed directly. Various DM detection experiments running for several years
have yielded no positive results. In view of these negative results, we had earlier proposed alternate models by postulating a minimum gravitational field strength (minimum
curvature) and a minimum acceleration. These postulates led to the modified Newtonian dynamics and modified Newtonian gravity (MONG). The observed flat rotation
curves of galaxies were also accounted for through these postulates. Here, we extend
these postulates to galaxy clusters and model the dynamical velocity-distance curve for
a typical cluster such as the Virgo cluster. The radial velocities of galaxies in the Virgo
cluster are also obtained through this model. Observations show an inconsistency in the
Hubble flow at a mean cluster distance of 17 Mpc, which is expected in regions of high
matter density. This decrease in velocity is predicted by our model of modified gravity
(MONG). The radial velocity versus distance relation for galaxies in the Virgo cluster
obtained using MONG is in agreement with observations.
