Galaxies and Dark Matter: an unhappy couple

Idranil Banik

The standard cosmological paradigm is based on classical gravity being valid everywhere. However, the ultraweak gravity in the outskirts of galaxies means the quantised nature of gravity should become important. In such regions, one does in fact see a strong departure from the predictions of classical theories. If one is convinced of their validity in such regions, then one must add vast amounts of hypothetical dark matter to save the classical gravity theory. This unwieldy model based on an undiscovered particle runs into several astrophysical problems. In particular, the satellite galaxies of the Milky Way and Andromeda mostly fall within thin planes but also need dark matter, a contradiction I will explain. I will present a reasonable solution using an empirical acceleration-based modification to gravity that also works in other galaxies, each time removing the need for dark matter. This model may help explain puzzling motions of nearby galaxies which I helped uncover and published recently in an international prize-winning paper (MNRAS, 459, 2237).

Duration: 1 hour

Host: PhySoc