Abstract Details

Name: Louise Rebecca
Affiliation: Christ Junior College
Conference ID: ASI2021_130
Title : Modification of Newtonian Gravity: An extension to Galaxy Clusters
Authors and Co-Authors : C Sivaram Indian Institute of Astrophysics, Bangalore - 560 034, India Kenath Arun Christ Junior College, Bangalore - 560 029, India
Abstract Type : Poster
Abstract Category : General Relativity and Cosmology
Abstract : The presence of dark matter, though well established by indirect evidences is yet to be observed directly. Various dark matter detection experiments running for several years have yielded no positive results so far. In view of these negative results, we had proposed alternate models by postulating a minimum field strength (minimum curvature) and also minimum acceleration avoiding the introduction of DM and an ad hoc fundamental acceleration (to account for DM), since it naturally follows from the minimal acceleration. These postulates lead to the modified Newtonian dynamics and modified Newtonian gravity. The observed flat rotation curves of galaxies were accounted for through these postulates. Here we extend these postulates to galaxy clusters and model out the dynamical velocity-distance of such large-scale structures. These curves are found to consist of three regions. The region close to the center of the galaxy cluster, where the matter density dominates and is uniform giving a linear increase in velocity with distance. For regions away from the centre, as the matter density falls off with distance and the gravitational self-energy term dominates which gives a velocity that is independent of distance implying a flat region in the rotation curve (which is usually attributed to the presence of vast amounts of dark matter (DM)). As dark energy begins to dominate, the velocity is found to increase linearly with distance. In the case of the Virgo cluster, the dark energy is found to dominate from a distance of 20 Mpc from the centre. At this distance, the curve shifts from flat to linear. This is found to be consistent with observations. Our model is in complete agreement with observations, for instance, the plot obtained for Virgo cluster matches with that observed.