Abstract Details
| Name: Arun Kenath Affiliation: Christ (Deemed to be University), Bengaluru Conference ID: ASI2019_34 Title : Alternate to Dark Matter: MOND, MONG or MORG Authors and Co-Authors : Arun Kenath; S B Gudennavar; C Sivaram Abstract Type : Oral Abstract Category : General Relativity and Cosmology Abstract : Dark matter (DM) is supposed to constitute about 90% of the mass of typical galaxies and about a third of the density of the universe. Several candidates have been proposed for dark matter, from WIMPS to axions and many more. The postulated candidates for DM cover a range of about eighty orders of magnitude. Though there is indirect evidence for the presence of DM in the universe, it is still undetected and its nature still unknown. Several experiments to detect DM running for many years have yielded no positive results so far, only lower limits for their fluxes (for different DM particle masses) are set. Even the upgraded XENON1T has set most stringent limit on dark matter interaction cross-section but detection still remains elusive. This may necessitate the need for alternate models to DM. Modification of Newtonian Dynamics (MOND) was initially proposed as an alternative to account for the flat rotation curves of spiral galaxies, without invoking DM in the halo. The theory required an ad hoc introduction of a fundamental acceleration ~10^-8cm/s^2, below which Newtonian dynamics is modified to an effective force law. We consider another possible explanation for the flat rotation curve of the spiral galaxies by modifying the Newtonian gravity (MONG), where the gravitational potential will take a logarithmic form, giving a constant velocity dispersion. We also explore the relativistic theory of MOND which gives a new Tensor-Vector theory like MORG (Modification of Relativistic Gravity). Another possible way in which the need for DM may be avoided is explored by modifying the Einstein-Hilbert action. These theories have severe constraints from CMBR anisotropy and lensing. Here we set constraints on these theories based on observations and show that these modified models might be indistinguishable from the Newtonian case. |